DRUGS & SUPPLEMENTS
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Iso-Rifa (Isoniazid) is recommended for all forms of tuberculosis in which organisms are susceptible. However, active tuberculosis must be treated with multiple concomitant antituberculosis medications to prevent the emergence of drug resistance. Single-drug treatment of active tuberculosis with Iso-Rifa (Isoniazid), or any other medication, is inadequate therapy.
Iso-Rifa (Isoniazid) is recommended as preventive therapy for the following groups, regardless of age. (Note: the criterion for a positive reaction to a skin test (in millimeters of induration) for each group is given in parenthesis):
Preventive therapy may be considered for HIV infected persons who are tuberculin-negative but belong to groups in which the prevalence of tuberculosis infection is high. Candidates for preventive therapy who have HIV infection should have a minimum of 12 months of therapy.
Additionally, in the absence of any of the above risk factors, persons under the age of 35 with a tuberculin skin test reaction of 10 mm or more are also appropriate candidates for preventive therapy if they are a member of any of the following high-incidence groups:
Children who are less than 4 years old are candidates for Iso-Rifa (Isoniazid) preventive therapy if they have >10 mm induration from a PPD Mantoux tuberculin skin test.
Finally, persons under the age of 35 who a) have none of the above risk factors (1-6); b) belong to none of the high-incidence groups; and c) have a tuberculin skin test reaction of 15 mm or more, are appropriate candidates for preventive therapy.
The risk of hepatitis must be weighed against the risk of tuberculosis in positive tuberculin reactors over the age of 35. However, the use of Iso-Rifa (Isoniazid) is recommended for those with the additional risk factors listed above (1-6) and on an individual basis in situations where there is likelihood of serious consequences to contacts who may become infected.
Iso-Rifa (Isoniazid) is contraindicated in patients who develop severe hypersensitivity reactions, including drug-induced hepatitis; previous isoniazid-associated hepatic injury; severe adverse reactions to Iso-Rifa (Isoniazid) such as drug fever, chills, arthritis; and acute liver disease of any etiology.
See the boxed WARNING .
All drugs should be stopped and an evaluation made at the first sign of a hypersensitivity reaction. If Iso-Rifa therapy must be reinstituted, the drug should be given only after symptoms have cleared. The drug should be restarted in very small and gradually increasing doses and should be withdrawn immediately if there is any indication of recurrent hypersensitivity reaction.
Use of Iso-Rifa (Isoniazid) should be carefully monitored in the following:
Because there is a higher frequency of Iso-Rifa (Isoniazid) associated hepatitis among certain patient groups, including Age > 35, daily users of alcohol, chronic liver disease, injection drug use and women belonging to minority groups, particularly in the post-partum period, transaminase measurements should be obtained prior to starting and monthly during preventative therapy, or more frequently as needed. If any of the values exceed three to five times the upper limit of normal, Iso-Rifa (Isoniazid) should be temporarily discontinued and consideration given to restarting therapy.
Iso-Rifa should not be administered with food. Studies have shown that the bioavailability of Iso-Rifa (Isoniazid) is reduced significantly when administered with food. Tyramine- and histamine-containing foods should be avoided in patients receiving Iso-Rifa (Isoniazid). Because Iso-Rifa (Isoniazid) has some monoamine oxidase inhibiting activity, an interaction with tyramine-containing foods (cheese, red wine) may occur. Diamine oxidase may also be inhibited, causing exaggerated response (e.g., headache, sweating, palpitations, flushing, hypotension) to foods containing histamine (e.g., skipjack, tuna, other tropical fish).
A report of severe acetaminophen toxicity was reported in a patient receiving Iso-Rifa (Isoniazid). It is believed that the toxicity may have resulted from a previously unrecognized interaction between Iso-Rifa (Isoniazid) and acetaminophen and a molecular basis for this interaction has been proposed. However, current evidence suggests that Iso-Rifa (Isoniazid) does induce P-450IIE1, a mixed-function oxidase enzyme that appears to generate the toxic metabolites, in the liver. Furthermore it has been proposed that Iso-Rifa (Isoniazid) resulted in induction of P-450IIE1 in the patients liver which, in turn, resulted in a greater proportion of the ingested acetaminophen being converted to the toxic metabolites. Studies have demonstrated that pretreatment with Iso-Rifa (Isoniazid) potentiates acetaminophen hepatotoxicity in rats1,2.
Iso-Rifa is known to slow the metabolism of carbamazepine and increase its serum levels. Carbamazepine levels should be determined prior to concurrent administration with Iso-Rifa (Isoniazid), signs and symptoms of carbamazepine toxicity should be monitored closely, and appropriate dosage adjustment of the anticonvulsant should be made3.
Potential interaction of ketoconazole and Iso-Rifa (Isoniazid) may exist. When ketoconazole is given in combination with Iso-Rifa (Isoniazid) and rifampin the AUC of ketoconazole is decreased by as much as 88% after 5 months of concurrent Iso-Rifa (Isoniazid) and rifampin therapy4.
Iso-Rifa may increase serum levels of phenytoin. To avoid phenytoin intoxication, appropriate adjustment of the anticonvulsant should be made5,6.
A recent study has shown that concomitant administration of Iso-Rifa (Isoniazid) and theophylline may cause elevated plasma levels of theophylline, and in some instances a slight decrease in the elimination of Iso-Rifa (Isoniazid). Since the therapeutic range of theophylline is narrow, theophylline serum levels should be monitored closely, and appropriate dosage adjustments of theophylline should be made7.
A recent case study has shown a possible increase in the plasma level of valproate when co-administered with Iso-Rifa. Plasma valproate concentration should be monitored when Iso-Rifa (Isoniazid) and valproate are co-administered, and appropriate dosage adjustments of valproate should be made8.
Iso-Rifa (Isoniazid) has been shown to induce pulmonary tumors in a number of strains of mice. Iso-Rifa (Isoniazid) has not been shown to be carcinogenic in humans. (Note: a diagnosis of mesothelioma in a child with prenatal exposure to Iso-Rifa (Isoniazid) and no other apparent risk factors has been reported). Iso-Rifa (Isoniazid) has been found to be weakly mutagenic in strains TA 100 and TA 1535 of Salmonella typhimurium (Ames assay) without metabolic activation.
Iso-Rifa has been shown to have an embryocidal effect in rats and rabbits when given orally during pregnancy. Iso-Rifa (Isoniazid) was not teratogenic in reproduction studies in mice, rats and rabbits. There are no adequate and well-controlled studies in pregnant women. Iso-Rifa (Isoniazid) should be used as a treatment for active tuberculosis during pregnancy because the benefit justifies the potential risk to the fetus. The benefit of preventive therapy also should be weighed against a possible risk to the fetus. Preventive therapy generally should be started after delivery to prevent putting the fetus at risk of exposure; the low levels of Iso-Rifa (Isoniazid) in breast milk do not threaten the neonate. Since Iso-Rifa (Isoniazid) is known to cross the placental barrier, neonates of Iso-Rifa (Isoniazid) treated mothers should be carefully observed for any evidence of adverse affects.
Since Iso-Rifa (Isoniazid) is known to cross the placental barrier, neonates of isoniazid-treated mothers should be carefully observed for any evidence of adverse effects.
The small concentrations of Iso-Rifa (Isoniazid) in breast milk do not produce toxicity in the nursing newborn; therefore, breast feeding should not be discouraged. However, because levels of Iso-Rifa (Isoniazid) are so low in breast milk, they can not be relied upon for prophylaxis or therapy of nursing infants.
The most frequent reactions are those affecting the nervous system and the liver.
Nervous System Reactions - Peripheral neuropathy is the most common toxic effect. It is dose-related, occurs most often in the malnourished and in those predisposed to neuritis (e.g., alcoholics and diabetics), and is usually preceded by paresthesias of the feet and hands. The incidence is higher in "slow inactivators".
Other neurotoxic effects, which are uncommon with conventional doses, are convulsions, toxic encephalopathy, optic neuritis and atrophy, memory impairment, and toxic psychosis.
Hepatic Reactions - See boxed WARNING. Elevated serum transaminase (SGOT; SGPT), bilirubinemia, bilirubinuria, jaundice, and occasionally severe and sometimes fatal hepatitis. The common prodromal symptoms of hepatitis are anorexia, nausea, vomiting, fatigue, malaise, and weakness. Mild hepatic dysfunction, evidenced by mild and transient elevation of serum transaminase levels occurs in 10% to 20% of patients taking Iso-Rifa (Isoniazid). This abnormality usually appears in the first 1 to 3 months of treatment but can occur at any time during therapy. In most instances, enzyme levels return to normal, and generally, there is no necessity to discontinue medication during the period of mild serum transaminase elevation. In occasional instances, progressive liver damage occurs, with accompanying symptoms. If the SGOT value exceeds three to five times the upper limit of normal, discontinuation of the Iso-Rifa (Isoniazid) should be strongly considered. The frequency of progressive liver damage increases with age. It is rare in persons under 20, but occurs in up to 2.3 percent of those over 50 years of age.
Gastrointestinal Reactions - Nausea, vomiting, and epigastric distress.
Hematologic Reactions - Agranulocytosis; hemolytic, sideroblastic, or aplastic anemia, thrombocytopenia; and eosinophilia.
Hypersensitivity Reactions - Fever, skin eruptions (morbilliform, maculopapular, purpuric, or exfoliative), lymphadenopathy, and vasculitis.
Metabolic and Endocrine Reactions - Pyridoxine deficiency, pellagra, hyperglycemia, metabolic acidosis, and gynecomastia.
Miscellaneous Reactions - Rheumatic syndrome and systemic lupus erythematosus-like syndrome.
To report SUSPECTED ADVERSE REACTIONS, contact West-ward Pharmaceutical Corp. at 1-877-233-2001, and the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Iso-Rifa overdosage produces signs and symptoms within 30 minutes to 3 hours after ingestion. Nausea, vomiting, dizziness, slurring of speech, blurring of vision, and visual hallucinations (including bright colors and strange designs) are among the early manifestations. With marked overdosage, respiratory distress and CNS depression, progressing rapidly from stupor to profound coma, are to be expected, along with severe, intractable seizures. Severe metabolic acidosis, acetonuria, and hyperglycemia are typical laboratory findings.
Untreated or inadequately treated cases of gross Iso-Rifa (Isoniazid) overdosage, 80 mg/kg - 150 mg/kg, can cause neurotoxicity6 and terminate fatally, but good response has been reported in most patients brought under adequate treatment within the first few hours after drug ingestion.
Absorption of drugs from the GI tract may be decreased by giving activated charcoal. Gastric emptying should also be employed in the asymptomatic patient. Safeguard the patient"s airway when employing these procedures. Patients who acutely ingest > 80 mg/kg should be treated with intravenous pyridoxine on a gram per gram basis equal to the Iso-Rifa dose. If an unknown amount of Iso-Rifa (Isoniazid) is ingested, consider an initial dose of 5 grams of pyridoxine given over 30 to 60 minutes in adults, or 80 mg/kg of pyridoxine in children.
Ensure adequate ventilation, support cardiac output, and protect the airway while treating seizures and attempting to limit absorption. If the dose of Iso-Rifa (Isoniazid) is known, the patient should be treated initially with a slow intravenous bolus of pyridoxine, over 3 to 5 minutes, on a gram per gram basis, equal to the Iso-Rifa (Isoniazid) dose. If the quantity of Iso-Rifa (Isoniazid) ingestion is unknown, then consider an initial intravenous bolus of pyridoxine of 5 grams in the adult or 80 mg/kg in the child. If seizures continue, the dosage of pyridoxine may be repeated. It would be rare that more than 10 grams of pyridoxine would need to be given. The maximum safe dose for pyridoxine in Iso-Rifa (Isoniazid) intoxication is not known. If the patient does not respond to pyridoxine, diazepam may be administered. Phenytoin should be used cautiously, because Iso-Rifa (Isoniazid) interferes with the metabolism of phenytoin.
Obtain blood samples for immediate determination of gases, electrolytes, BUN, glucose, etc.; type and cross-match blood in preparation for possible hemodialysis.
Patients with this degree of INH intoxication are likely to have hypoventilation. The administration of sodium bicarbonate under these circumstances can cause exacerbation of hypercarbia. Ventilation must be monitored carefully, by measuring blood carbon dioxide levels, and supported mechanically, if there is respiratory insufficiency.
Both peritoneal and hemodialysis have been used in the management of Iso-Rifa (Isoniazid) overdosage. These procedures are probably not required if control of seizures and acidosis is achieved with pyridoxine, diazepam and bicarbonate.
Along with measures based on initial and repeated determination of blood gases and other laboratory tests as needed, utilize meticulous respiratory and other intensive care to protect against hypoxia, hypotension, aspiration, pneumonitis, etc.
: NOTE: For preventive therapy of tuberculous infection and treatment of tuberculosis, it is recommended that physicians be familiar with the following publications: (1) the recommendations of the Advisory Council for the Elimination of Tuberculosis, published in the MMWR: vol 42; RR-4, 1993 and (2) Treatment of Tuberculosis and Tuberculosis Infection in Adults and Children, American Journal of Respiratory and Critical Care Medicine: vol 149; 1359-1374, 1994.
For Treatment of Tuberculosis - Iso-Rifa (Isoniazid) is used in conjunction with other effective anti-tuberculosis agents. Drug susceptibility testing should be performed on the organisms initially isolated from all patients with newly diagnosed tuberculosis. If the bacilli become resistant, therapy must be changed to agents to which the bacilli are susceptible.
Usual Oral Dosage (depending on the regimen used):
15 mg/kg up to 900 mg day, two or three times/week
20-40 mg/kg up to 900 mg/day, two or three time/week
There are 3 regimen options for the initial treatment of tuberculosis in children and adults:
Option 1: Daily Iso-Rifa (Isoniazid), rifampin, and pyrazinamide for 8 weeks followed by 16 weeks of Iso-Rifa (Isoniazid) and rifampin daily or 2-3 times weekly. Ethambutol or streptomycin should be added to the initial regimen until sensitivity to Iso-Rifa (Isoniazid) and rifampin is demonstrated. The addition of a fourth drug is optional if the relative prevalence of isoniazid-resistant Mycobacterium tuberculosis isolates in the community is less than or equal to four percent.
Option 2: Daily Iso-Rifa (Isoniazid), rifampin, pyrazinamide, and streptomycin or ethambutol for 2 weeks followed by twice weekly administration of the same drugs for 6 weeks, subsequently twice weekly Iso-Rifa (Isoniazid) and rifampin for 16 weeks.
Option 3: Three times weekly with Iso-Rifa (Isoniazid), rifampin, pyrazinamide, and ethambutol or streptomycin for 6 months.
*All regimens given twice weekly or 3 times weekly should be administered by directly observed therapy.
The above treatment guidelines apply only when the disease is caused by organisms that are susceptible to the standard antituberculous agents. Because of the impact of resistance to Iso-Rifa (Isoniazid) and rifampin on the response to therapy, it is essential that physicians initiating therapy for tuberculosis be familiar with the prevalence of drug resistance in their communities. It is suggested that ethambutol not be used in children whose visual acuity cannot be monitored.
The response of the immunologically impaired host to treatment may not be as satisfactory as that of a person with normal host responsiveness. For this reason, therapeutic decisions for the impaired host must be individualized. Since patients co-infected with HIV may have problems with malabsorption, screening of antimycobacterial drug levels, especially in patients with advanced HIV disease, may be necessary to prevent the emergence of MDRTB.
The basic principles that underlie the treatment of pulmonary tuberculosis also apply to Extra pulmonary forms of the disease. Although there have not been the same kinds of carefully conducted controlled trials of treatment of Extra pulmonary tuberculosis as for pulmonary disease, increasing clinical experience indicates that a 6 to 9 month short-course regimen is effective. Because of the insufficient data, miliary tuberculosis, bone/joint tuberculosis, and tuberculous meningitis in infants and children should receive 12 months therapy.
Bacteriologic evaluation of Extra pulmonary tuberculosis may be limited by the relative inaccessibility of the sites of disease. Thus, response to treatment often must be judged on the basis of clinical and radiographic findings.
The use of adjunctive therapies such as surgery and corticosteroids is more commonly required in Extra pulmonary tuberculosis than in pulmonary disease. Surgery may be necessary to obtain specimens for diagnosis and to treat such processes as constrictive pericarditis and spinal cord compression from Pott's Disease. Corticosteriods have been shown to be of benefit in preventing cardiac constriction from tuberculous pericarditis and in decreasing the neurologic sequelae of all stages of tuberculosis meningitis, especially when administered early in the course of the disease.
The options listed above must be adjusted for the pregnant patient. Streptomycin interferes with in utero development of the ear and may cause congenital deafness. Routine use of pyrazinamide is also not recommended in pregnancy because of inadequate teratogenicity data. The initial treatment regimen should consist of Iso-Rifa and rifampin. Ethambutol should be included unless primary Iso-Rifa (Isoniazid) resistance is unlikely (isoniazid resistance rate documented to be less than 4%).
Multiple-drug resistant tuberculosis (i.e., resistance to at least Iso-Rifa (Isoniazid) and rifampin) presents difficult treatment problems. Treatment must be individualized and based on susceptibility studies. In such cases, consultation with an expert in tuberculosis is recommended.
A major cause of drug-resistant tuberculosis is patient non-compliance with treatment. The use of DOT can help assure patient compliance with drug therapy. DOT is the observation of the patient by a health care provider or other responsible person as the patient ingests anti-tuberculosis medications. DOT can be achieved with daily, twice weekly or thrice weekly regimens, and is recommended for all patients.
Before Iso-Rifa (Isoniazid) preventive therapy is initiated, bacteriologically positive or radiographically progressive tuberculosis must be excluded. Appropriate evaluations should be performed if Extra pulmonary tuberculosis is suspected.
Adults over 30 Kg: 300 mg per day in a single dose.
Infants and Children: 10 mg/kg (up to 300 mg daily) in a single dose. In situations where adherence with daily preventative therapy cannot be assured, 20-30 mg/kg (not to exceed 900 mg) twice weekly under the direct observation of a health care worker at the time of administration8.
Continuous administration of Iso-Rifa (Isoniazid) for a sufficient period is an essential part of the regimen because relapse rates are higher if chemotherapy is stopped prematurely. In the treatment of tuberculosis, resistant organisms may multiply and the emergence of resistant organisms during the treatment may necessitate a change in the regimen.
For following patient compliance: the Potts-Cozart test9, a simple colorimetric6 method of checking for Iso-Rifa (Isoniazid) in the urine, is a useful tool for assuring patient compliance, which is essential for effective tuberculosis control. Additionally, Iso-Rifa (Isoniazid) test strips are also available to check patient compliance.
Concomitant administration of pyridoxine (B6) is recommended in the malnourished and in those predisposed to neuropathy (e.g., alcoholics and diabetics).
Iso-Rifa (Isoniazid) Tablets, USP 100 mg: White, Round Tablets; Debossed "West-ward" on one side and "260" on the Scored side.
Iso-Rifa (Isoniazid) Tablets, USP 300 mg: White, Round Tablets; Debossed "West-ward 261" on one side and Scored on the other side.
Store at 20-25°C (68-77°F). Protect from light and moisture.
Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.
Adults and Children. Amer. J. Respir Crit Care Med.1994; 149: p 1359-1374.
Committee on Infectious Diseases; 23rd edition; p487.
West-ward Pharmaceutical Corp.
Eatontown, NJ 07724
Revised February 2011
Iso-Rifa (Isoniazid) 300mg Tablet
In the treatment of both tuberculosis and the meningococcal carrier state, the small number of resistant cells present within large populations of susceptible cells can rapidly become the predominant type. Bacteriologic cultures should be obtained before the start of therapy to confirm the susceptibility of the organism to Iso-Rifa and they should be repeated throughout therapy to monitor the response to treatment. Since resistance can emerge rapidly, susceptibility tests should be performed in the event of persistent positive cultures during the course of treatment. If test results show resistance to Iso-Rifa (Rifampin) and the patient is not responding to therapy, the drug regimen should be modified.
Iso-Rifa (Rifampin) is indicated in the treatment of all forms of tuberculosis.
A three-drug regimen consisting of Iso-Rifa (Rifampin), isoniazid, and pyrazinamide (e.g., RIFATER® manufactured by Sanofi Aventis) is recommended in the initial phase of short-course therapy which is usually continued for 2 months. The Advisory Council for the Elimination of Tuberculosis, the American Thoracic Society, and Centers for Disease Control and Prevention recommend that either streptomycin or ethambutol be added as a fourth drug in a regimen containing isoniazid (INH), Iso-Rifa (Rifampin), and pyrazinamide for initial treatment of tuberculosis unless the likelihood of INH resistance is very low. The need for a fourth drug should be reassessed when the results of susceptibility testing are known. If community rates of INH resistance are currently less than 4%, an initial treatment regimen with less than four drugs may be considered.
Following the initial phase, treatment should be continued with Iso-Rifa (Rifampin) and isoniazid (e.g., RIFAMATE® manufactured by Sanofi Aventis) for at least 4 months. Treatment should be continued for longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.
Iso-Rifa (Rifampin) for injection is indicated for the initial treatment and retreatment of tuberculosis when the drug cannot be taken by mouth.
Iso-Rifa (Rifampin) is indicated for the treatment of asymptomatic carriers of Neisseria meningitidis to eliminate meningococci from the nasopharynx. Iso-Rifa (Rifampin) is not indicated for the treatment of meningococcal infection because of the possibility of the rapid emergence of resistant organisms. (See WARNINGS .)
Iso-Rifa (Rifampin) should not be used indiscriminately, and therefore, diagnostic laboratory procedures, including serotyping and susceptibility testing, should be performed for establishment of the carrier state and the correct treatment. So that the usefulness of Iso-Rifa (Rifampin) in the treatment of asymptomatic meningococcal carriers is preserved, the drug should be used only when the risk of meningococcal disease is high.
To reduce the development of drug-resistant bacteria and maintain the effectiveness of Iso-Rifa (Rifampin) and other antibacterial drugs, Iso-Rifa (Rifampin) should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.
Iso-Rifa (Rifampin) is contraindicated in patients with a history of hypersensitivity to Iso-Rifa (Rifampin) or any of the components, or to any of the rifamycins. (See WARNINGS .)
Iso-Rifa (Rifampin) is contraindicated in patients who are also receiving ritonavir-boosted saquinavir due to an increased risk of severe hepatocellular toxicity. (See PRECAUTIONS, Drug Interactions .) Iso-Rifa (Rifampin) is contraindicated in patients who are also receiving atazanavir, darunavir, fosamprenavir, saquinavir, or tipranavir due to the potential of Iso-Rifa (Rifampin) to substantially decrease plasma concentrations of these antiviral drugs, which may result in loss of antiviral efficacy and/or development of viral resistance.
Iso-Rifa (Rifampin) has been shown to produce liver dysfunction. Fatalities associated with jaundice have occurred in patients with liver disease and in patients taking Iso-Rifa (Rifampin) with other hepatotoxic agents. Patients with impaired liver function should be given Iso-Rifa (Rifampin) only in cases of necessity and then with caution and under strict medical supervision. In these patients, careful monitoring of liver function, especially SGPT/ALT and SGOT/AST should be carried out prior to therapy and then every 2 to 4 weeks during therapy. If signs of hepatocellular damage occur, Iso-Rifa (Rifampin) should be withdrawn.
In some cases, hyperbilirubinemia resulting from competition between Iso-Rifa (Rifampin) and bilirubin for excretory pathways of the liver at the cell level can occur in the early days of treatment. An isolated report showing a moderate rise in bilirubin and/or transaminase level is not in itself an indication for interrupting treatment; rather, the decision should be made after repeating the tests, noting trends in the levels, and considering them in conjunction with the patient's clinical condition.
Iso-Rifa (Rifampin) has enzyme-inducing properties, including induction of delta amino levulinic acid synthetase. Isolated reports have associated porphyria exacerbation with Iso-Rifa (Rifampin) administration. The possibility of rapid emergence of resistant meningococci restricts the use of Iso-Rifa (Rifampin) to short-term treatment of the asymptomatic carrier state. Iso-Rifa (Rifampin) is not to be used for the treatment of meningococcal disease.
Iso-Rifa should be used with caution in patients with a history of diabetes mellitus, as diabetes management may be more difficult.
Prescribing Iso-Rifa (Rifampin) in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.
For the treatment of tuberculosis, Iso-Rifa (Rifampin) is usually administered on a daily basis. Doses of Iso-Rifa (Rifampin) greater than 600 mg given once or twice weekly have resulted in a higher incidence of adverse reactions, including the "flu syndrome" (fever, chills and malaise), hematopoietic reactions (leukopenia, thrombocytopenia, or acute hemolytic anemia), cutaneous, gastrointestinal, and hepatic reactions, shortness of breath, shock, anaphylaxis, and renal failure. Recent studies indicate that regimens using twice-weekly doses of Iso-Rifa (Rifampin) 600 mg plus isoniazid 15 mg/kg are much better tolerated.
Iso-Rifa (Rifampin) is not recommended for intermittent therapy; the patient should be cautioned against intentional or accidental interruption of the daily dosage regimen since rare renal hypersensitivity reactions have been reported when therapy was resumed in such cases.
Iso-Rifa (Rifampin) has enzyme induction properties that can enhance the metabolism of endogenous substrates including adrenal hormones, thyroid hormones, and vitamin D. Iso-Rifa (Rifampin) and isoniazid have been reported to alter vitamin D metabolism. In some cases, reduced levels of circulating 25-hydroxy vitamin D and 1,25-dihydroxy vitamin D have been accompanied by reduced serum calcium and phosphate, and elevated parathyroid hormone.
For intravenous infusion only. Must not be administered by intramuscular or subcutaneous route. Avoid extravasation during injection: local irritation and inflammation due to extravascular infiltration of the infusion have been observed. If these occur, the infusion should be discontinued and restarted at another site.
Patients should be counseled that antibacterial drugs including Iso-Rifa should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When Iso-Rifa (Rifampin) is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by Iso-Rifa (Rifampin) or other antibacterial drugs in the future.
The patient should be told that Iso-Rifa (Rifampin) may produce a reddish coloration of the urine, sweat, sputum, and tears, and the patient should be forewarned of this. Soft contact lenses may be permanently stained.
The patient should be advised that the reliability of oral or other systemic hormonal contraceptives may be affected; consideration should be given to using alternative contraceptive measures.
Patients should be instructed to notify their physicians promptly if they experience any of the following: fever, loss of appetite, malaise, nausea and vomiting, darkened urine, yellowish discoloration of the skin and eyes, and pain or swelling of the joints.
Compliance with the full course of therapy must be emphasized, and the importance of not missing any doses must be stressed.
Adults treated for tuberculosis with Iso-Rifa (Rifampin) should have baseline measurements of hepatic enzymes, bilirubin, serum creatinine, a complete blood count, and a platelet count (or estimate). Baseline tests are unnecessary in pediatric patients unless a complicating condition is known or clinically suspected.
Patients should be seen at least monthly during therapy and should be specifically questioned concerning symptoms associated with adverse reactions. All patients with abnormalities should have follow-up, including laboratory testing, if necessary. Routine laboratory monitoring for toxicity in people with normal baseline measurements is generally not necessary.
Healthy subjects who received Iso-Rifa 600 mg once daily concomitantly with saquinavir 1000 mg/ritonavir 100 mg twice daily (ritonavir-boosted saquinavir) developed severe hepatocellular toxicity. Therefore, concomitant use of these medications is contraindicated. (See CONTRAINDICATIONS.)
Iso-Rifa (Rifampin) is known to induce certain cytochrome P-450 enzymes. Administration of Iso-Rifa (Rifampin) with drugs that undergo biotransformation through these metabolic pathways may accelerate elimination of coadministered drugs. To maintain optimum therapeutic blood levels, dosages of drugs metabolized by these enzymes may require adjustment when starting or stopping concomitantly administered Iso-Rifa (Rifampin).
Iso-Rifa (Rifampin) has been reported to substantially decrease the plasma concentrations of the following antiviral drugs: atazanavir, darunavir, fosamprenavir, saquinavir, and tipranavir. These antiviral drugs must not be co-administered with Iso-Rifa (Rifampin). (See CONTRAINDICATIONS .)
Iso-Rifa (Rifampin) has been reported to accelerate the metabolism of the following drugs: anticonvulsants (e.g., phenytoin), digitoxin, antiarrhythmics (e.g., disopyramide, mexiletine, quinidine, tocainide), oral anticoagulants, antifungals (e.g., fluconazole, itraconazole, ketoconazole), barbiturates, beta-blockers, calcium channel blockers (e.g., diltiazem, nifedipine, verapamil), chloramphenicol, clarithromycin, corticosteroids, cyclosporine, cardiac glycoside preparations, clofibrate, oral or other systemic hormonal contraceptives, dapsone, diazepam, doxycycline, fluoroquinolones (e.g., ciprofloxacin), haloperidol, oral hypoglycemic agents (sulfonylureas), levothyroxine, methadone, narcotic analgesics, progestins, quinine, tacrolimus, theophylline tricyclic antidepressants (e.g., amitriptyline, nortriptyline) and zidovudine. It may be necessary to adjust the dosages of these drugs if they are given concurrently with Iso-Rifa (Rifampin).
Patients using oral or other systemic hormonal contraceptives should be advised to change to nonhormonal methods of birth control during Iso-Rifa (Rifampin) therapy.
Iso-Rifa (Rifampin) has been observed to increase the requirements for anticoagulant drugs of the coumarin type. In patients receiving anticoagulants and Iso-Rifa (Rifampin) concurrently, it is recommended that the prothrombin time be performed daily or as frequently as necessary to establish and maintain the required dose of anticoagulant.
When the two drugs were taken concomitantly, decreased concentrations of atovaquone and increased concentrations of Iso-Rifa were observed.
Concurrent use of ketoconazole and Iso-Rifa (Rifampin) has resulted in decreased serum concentrations of both drugs. Concurrent use of Iso-Rifa (Rifampin) and enalapril has resulted in decreased concentrations of enalaprilat, the active metabolite of enalapril. Dosage adjustments should be made if indicated by the patient's clinical condition.
Concomitant antacid administration may reduce the absorption of Iso-Rifa (Rifampin). Daily doses of Iso-Rifa (Rifampin) should be given at least 1 hour before the ingestion of antacids.
Probenecid and cotrimoxazole have been reported to increase the blood level of Iso-Rifa (Rifampin).
When Iso-Rifa (Rifampin) is given concomitantly with either halothane or isoniazid, the potential for hepatotoxicity is increased. The concomitant use of Iso-Rifa (Rifampin) and halothane should be avoided. Patients receiving both Iso-Rifa (Rifampin) and isoniazid should be monitored close for hepatotoxicity.
Plasma concentrations of sulfapyridine may be reduced following the concomitant administration of sulfasalazine and Iso-Rifa (Rifampin). This finding may be the result of alteration in the colonic bacteria responsible for the reduction of sulfasalazine to sulfapyridine and mesalamine.
Cross-reactivity and false-positive urine screening tests for opiates have been reported in patients receiving Iso-Rifa (Rifampin) when using the KIMS (Kinetic Interaction of Microparticles in Solution) method (e.g., Abuscreen OnLine opiates assay; Roche Diagnostic Systems). Confirmatory tests, such as gas chromatography/mass spectrometry, will distinguish Iso-Rifa (Rifampin) from opiates.
Therapeutic levels of Iso-Rifa (Rifampin) have been shown to inhibit standard microbiological assays for serum folate and vitamin B12. Thus, alternate assay methods should be considered. Transient abnormalities in liver function tests (e.g., elevation in serum bilirubin, alkaline phosphatase, and serum transaminases) and reduced biliary excretion of contrast media used for visualization of the gallbladder have also been observed. Therefore, these tests should be performed before the morning dose of Iso-Rifa (Rifampin).
A few cases of accelerated growth of lung carcinoma have been reported in man, but a causal relationship with the drug has not been established. Hepatomas were increased in female mice dosed for 60 weeks with rifampicin followed by an observation period of 46 weeks, at 20 to 120 mg/kg (equivalent to 0.1 to 0.5 times the maximum dosage used clinically, based on body surface area comparisons). There was no evidence of tumorigenicity in male C3Hf/DP mice or in similar studies in BALB/c mice, or in two year studies in Wistar rats.
There was no evidence of mutagenicity in both prokaryotic (Salmonella typhi, Escherichia coli) and eukaryotic (Saccharomyces cerevisiae) bacteria, Drosophila melanogaster, or ICR/Ha Swiss mice. An increase in chromatid breaks was noted when whole blood cell cultures were treated with Iso-Rifa (Rifampin). Increased frequency of chromosomal aberrations was observed in vitro in lymphocytes obtained from patients treated with combinations of Iso-Rifa (Rifampin), isoniazid, and pyrazinamide and combinations of streptomycin, Iso-Rifa (Rifampin), isoniazid, and pyrazinamide.
Iso-Rifa has been shown to be teratogenic in rodents. Congenital malformations, primarily spina bifida were increased in the offspring of pregnant rats given Iso-Rifa (Rifampin) during organogenesis at oral doses of 150 to 250 mg/kg/day (about 1 to 2 times the maximum recommended human dose based on body surface area comparisons). Cleft palate was increased in a dose-dependent fashion in fetuses of pregnant mice treated at oral doses of 50 to 200 mg/kg (about 0.2 to 0.8 times the maximum recommended human dose based on body surface area comparisons). Imperfect osteogenesis and embryotoxicity were also reported in pregnant rabbits given Iso-Rifa (Rifampin) at oral doses up to 200 mg/kg/day (about 3 times the maximum recommended human dose based on body surface area comparisons). There are no adequate and well-controlled studies of Iso-Rifa (Rifampin) in pregnant women. Iso-Rifa (Rifampin) has been reported to cross the placental barrier and appear in cord blood. Iso-Rifa (Rifampin) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
When administered during the last few weeks of pregnancy, Iso-Rifa can cause post-natal hemorrhages in the mother and infant for which treatment with vitamin K may be indicated.
Because of the potential for tumorigenicity shown for Iso-Rifa (Rifampin) in animal studies, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
See CLINICAL PHARMACOLOGY– Pediatrics ; see also DOSAGE AND ADMINISTRATION .
Clinical studies of Iso-Rifa (Rifampin) did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. Caution should therefore be observed in using Iso-Rifa (Rifampin) in elderly patients. (See WARNINGS ).
Heartburn, epigastric distress, anorexia, nausea, vomiting, jaundice, flatulence, cramps, and diarrhea have been noted in some patients. Although Clostridium difficile has been shown in vitro to be sensitive to Iso-Rifa, pseudomembranous colitis has been reported with the use of Iso-Rifa (Rifampin) (and other broad spectrum antibiotics). Therefore, it is important to consider this diagnosis in patients who develop diarrhea in association with antibiotic use.
Transient abnormalities in liver function tests (e.g., elevations in serum bilirubin,, alkaline phosphatase, serum transaminases) have been observed. Rarely, hepatitis or a shock-like syndrome with hepatic involvement and abnormal liver function tests has been reported.
Thrombocytopenia has occurred primarily with high dose intermittent therapy, but has also been noted after resumption of interrupted treatment. It rarely occurs during well supervised daily therapy. This effect is reversible if the drug is discontinued as soon as purpura occurs. Cerebral hemorrhage and fatalities have been reported when Iso-Rifa administration has been continued or resumed after the appearance of purpura.
Rare reports of disseminated intravascular coagulation have been observed.
Leukopenia, hemolytic anemia, and decreased hemoglobin have been observed.
Agranulocytosis has been reported very rarely.
Headache, fever, drowsiness, fatigue, ataxia, dizziness, inability to concentrate, mental confusion, behavioral changes, muscular weakness pains in extremities, and generalized numbness have been observed.
Psychoses have been rarely reported.
Rare reports of disseminated intravascular coagulation have been observed.
Visual disturbances have been observed.
Menstrual disturbances have been observed.
Rare reports of adrenal insufficiency in patients with compromised adrenal function have been observed.
Elevations in BUN and serum uric acid have been reported. Rarely, hemolysis, hemoglobinuria, hematuria, interstitial nephritis, acute tubular necrosis, renal insufficiency, and acute renal failure have been noted. These are generally considered to be hypersensitivity reactions. They usually occur during intermittent therapy or when treatment is resumed following intentional or accidental interruption of a daily dosage regimen, and are reversible when Iso-Rifa is discontinued and appropriate therapy instituted.
Cutaneous reactions are mild and self-limiting and do not appear to be hypersensitivity reactions. Typically, they consist of flushing and itching with or without a rash. More serious cutaneous reactions which may be due to hypersensitivity occur but are uncommon.
Occasionally, pruritus, urticaria, rash, pemphigoid reaction, erythema multiforme including Stevens-Johnson Syndrome, toxic epidermal necrolysis, vasculitis, eosinophilia, sore mouth, sore tongue, and conjunctivitis have been observed.
Anaphylaxis has been reported rarely.
Edema of the face and extremities has been reported. Other reactions reported to have occurred with intermittent dosage regimens include "flu syndrome" (such as episodes of fever, chills, headache, dizziness, and bone pain), shortness of breath, wheezing, decrease in blood pressure and shock. The "flu syndrome" may also appear if Iso-Rifa (Rifampin) is taken irregularly by the patient or if daily administration is resumed after a drug free interval.
Nausea, vomiting, abdominal pain, pruritus, headache, and increasing lethargy will probably occur within a short time after ingestion; unconsciousness may occur when there is severe hepatic disease. Transient increases in liver enzymes and/or bilirubin may occur. Brownish-red or orange discoloration of the skin, urine, sweat, saliva, tears, and feces will occur, and its intensity is proportional to the amount ingested.
Liver enlargement, possibly with tenderness, can develop within a few hours after severe overdosage; bilirubin levels may increase and jaundice may develop rapidly. Hepatic involvement may be more marked in patients with prior impairment of hepatic function. Other physical findings remain essentially normal. A direct effect upon the hematopoietic system, electrolyte levels, or acid-base balance is unlikely.
Facial or periorbital edema has also been reported in pediatric patients. Hypotension, sinus tachycardia, ventricular arrhythmias, seizures and cardiac arrest were reported in some fatal cases.
The minimum acute lethal or toxic dose is not well established. However, nonfatal acute overdoses in adults have been reported with doses ranging from 9 to 12 gm Iso-Rifa. Fatal acute overdoses in adults have been reported with doses ranging from 14 to 60 gm. Alcohol or a history of alcohol abuse was involved in some of the fatal and nonfatal reports. Nonfatal overdoses in pediatric patients ages 1 to 4 years old of 100 mg/kg for one to two doses has been reported.
Intensive support measures should be instituted and individual symptoms treated as they arise. The airway should be secured and adequate respiratory exchange established. Since nausea and vomiting are likely to be present, gastric lavage within the first 2 to 3 hours after ingestion is probably preferable to induction of emesis. Following evacuation of the gastric contents, the instillation of activated charcoal slurry into the stomach may help absorb any remaining drug from the gastrointestinal tract. Antiemetic medication may be required to control severe nausea and vomiting.
Active diuresis (with measured intake and output) will help promote excretion of the drug.
For severe cases, extracorporeal hemodialysis may be required. If this is not available, peritoneal dialysis can be used along with forced diuresis.
Iso-Rifa can be administered by IV infusion (see INDICATIONS AND USAGE ).
See CLINICAL PHARMACOLOGY for dosing information in patients with renal failure.
Adults: 10 mg/kg, in a single daily administration, not to exceed 600 mg/day, IV
Pediatric Patients: 10–20 mg/kg, not to exceed 600 mg/day, IV
Iso-Rifa (Rifampin) is indicated in the treatment of all forms of tuberculosis. A three-drug regimen consisting of Iso-Rifa (Rifampin), isoniazid, and pyrazinamide (e.g., RIFATER® manufactured by Sanofi Aventis) is recommended in the initial phase of short-course therapy which is usually continued for 2 months. The Advisory Council for the Elimination of Tuberculosis, the American Thoracic Society, and the Centers for Disease Control and Prevention recommend that either streptomycin or ethambutol be added as a fourth drug in a regimen containing isoniazid (INH), Iso-Rifa (Rifampin) and pyrazinamide for initial treatment of tuberculosis unless the likelihood of INH resistance is very low. The need for a fourth drug should be reassessed when the results of susceptibility testing are known. If community rates of INH resistance are currently less than 4%, an initial treatment regimen with less than four drugs may be considered.
Following the initial phase, treatment should be continued with Iso-Rifa (Rifampin) and isoniazid (e.g., RIFAMATE® manufactured by Sanofi Aventis) for at least 4 months. Treatment should be continued for longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.
Reconstitute the lyophilized powder by transferring 10 mL of sterile water for injection to a vial containing 600 mg of Iso-Rifa for injection. Swirl vial gently to completely dissolve the antibiotic. The reconstituted solution contains 60 mg Iso-Rifa (Rifampin) per mL and is stable at room temperature for 24 hours. Prior to administration, withdraw from the reconstituted solution a volume equivalent to the amount of Iso-Rifa (Rifampin) calculated to be administered and add to 500 mL of infusion medium. Mix well and infuse at a rate allowing for complete infusion within 3 hours. Alternatively, the amount of Iso-Rifa (Rifampin) calculated to be administered may be added to 100 mL of infusion medium and infused in 30 minutes.
Dilutions in dextrose 5% for injection (D5W) are stable at room temperature for up to 4 hours and should be prepared and used within this time. Precipitation of Iso-Rifa (Rifampin) from the infusion solution may occur beyond this time. Dilutions in normal saline are stable at room temperature for up to 24 hours and should be prepared and used within this time. Other infusion solutions are not recommended.
Physical incompatibility (precipitate) was observed with undiluted (5 mg/mL) and diluted (1 mg/mL in normal saline) diltiazem hydrochloride and Iso-Rifa (Rifampin) (6 mg/mL in normal saline) during simulated Y-site administration.
Adults: For adults, it is recommended that 600 mg Iso-Rifa (Rifampin) be administered twice daily for two days.
Pediatric Patients: Pediatric patients 1 month of age or older: 10 mg/kg (not to exceed 600 mg per dose) every 12 hours for two days.
Pediatric patients under 1 month of age: 5 mg/kg every 12 hours for two days.
Iso-Rifa for injection, USP is available in glass vials containing 600 mg Iso-Rifa (Rifampin) (NDC 0069-0112-01).
Store at 25°C (77°F); excursions permitted to 15–30°C (59–86°F). Avoid excessive heat (temperatures above 40°C or 104°F). Protect from light.
Iso-Rifa (Rifampin) for
For IV Infusion Only
Depending on the reaction of the Iso-Rifa after taken, if you are feeling dizziness, drowsiness or any weakness as a reaction on your body, Then consider Iso-Rifa not safe to drive or operate heavy machine after consumption. Meaning that, do not drive or operate heavy duty machines after taking the capsule if the capsule has a strange reaction on your body like dizziness, drowsiness. As prescribed by a pharmacist, it is dangerous to take alcohol while taking medicines as it exposed patients to drowsiness and health risk. Please take note of such effect most especially when taking Primosa capsule. It's advisable to consult your doctor on time for a proper recommendation and medical consultations.Is Iso-Rifa addictive or habit forming?
Medicines are not designed with the mind of creating an addiction or abuse on the health of the users. Addictive Medicine is categorically called Controlled substances by the government. For instance, Schedule H or X in India and schedule II-V in the US are controlled substances.
Please consult the medicine instruction manual on how to use and ensure it is not a controlled substance.In conclusion, self medication is a killer to your health. Consult your doctor for a proper prescription, recommendation, and guidiance.
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The information was verified by Dr. Rachana Salvi, MD Pharmacology