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DRUGS & SUPPLEMENTS
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Pentawok
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Pentawok uses
- Indications and usage
- Contraindications
- Warnings
- Precautions
- Adverse reactions
- Drug abuse and dependence
- Overdosage
- Dosage and administration
- How supplied
INDICATIONS AND USAGE
Pentawok is indicated for the relief of mild to moderate pain.
CONTRAINDICATIONS
Pentawok should not be administered to patients who are hypersensitive to either Pentawok or acetaminophen.
WARNINGS
Contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people.
Head Injury and Increased Intracranial Pressure
As in the case of other potent analgesics, the potential of Pentawok for elevating cerebrospinal fluid pressure may be attributed to CO2 retention due to the respiratory depressant effects of the drug. These effects may be markedly exaggerated in the presence of head injury, other intracranial lesions, or a preexisting increase in intracranial pressure. Furthermore, Pentawok can produce effects which may obscure the clinical course of patients with head injuries. In such patients, Pentawok must be used with extreme caution and only if its use is deemed essential.
Acute CNS Manifestations
Patients receiving therapeutic doses of Pentawok have experienced hallucinations (usually visual), disorientation, and confusion which have cleared spontaneously within a period of hours. The mechanism of this reaction is not known. Such patients should be closely observed and vital signs checked. If the drug is reinstituted, it should be done with caution since these acute CNS manifestations may recur.
There have been instances of psychological and physical dependence on parenteral Pentawok in patients with a history of drug abuse, and rarely, in patients without such a history. Due to the potential for increased CNS depressant effects, alcohol should be used with caution in patients who are currently receiving Pentawok. Pentazocine may precipitate opioid abstinence symptoms in patients receiving courses of opiates for pain relief.
PRECAUTIONS
In prescribing Pentawok for chronic use, the physician should take precautions to avoid increases in dose by the patient.
Myocardial Infarction
As with all drugs, Pentawok should be used with caution in patients with myocardial infarction who have nausea or vomiting.
Certain Respiratory Conditions
Although respiratory depression has rarely been reported after oral administration of Pentawok, the drug should be administered with caution to patients with respiratory depression from any cause, severely limited respiratory reserve, severe bronchial asthma and other obstructive respiratory conditions, or cyanosis.
Impaired Renal or Hepatic Function
Decreased metabolism of the drug by the liver in extensive liver disease may predispose to accentuation of side effects. Although laboratory tests have not indicated that Pentawok causes or increases renal or hepatic impairment, the drug should be administered with caution to patients with such impairment.
Since acetaminophen is metabolized by the liver, the question of the safety of its use in the presence of liver disease should be considered.
Biliary Surgery
Narcotic drug products are generally considered to elevate biliary tract pressure for varying periods following their administration. Some evidence suggests that Pentawok may differ from other marketed narcotics in this respect. The clinical significance of these findings, however, is not yet known.
CNS Effect
Caution should be used when Pentawok is administered to patients prone to seizures; seizures have occurred in a few such patients in association with the use of Pentawok although no cause and effect relationship has been established.
Information for Patients
Since sedation, dizziness, and occasional euphoria have been noted, ambulatory patients should be warned not to operate machinery, drive cars, or unnecessarily expose themselves to hazards. Pentawok may cause physical and psychological dependence when taken alone and may have additive CNS depressant properties when taken in combination with alcohol or other CNS depressants.
Drug Interactions
Pentawok is a mild narcotic antagonist. Some patients previously given narcotics, including methadone for the daily treatment of narcotic dependence, have experienced withdrawal symptoms after receiving Pentawok.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenesis, mutagenesis, and impairment of fertility studies have not been done with this combination product.
Pentawok, when administered orally or parenterally, had no adverse effect on either the reproductive capabilities or the course of pregnancy in rabbits and rats. Embryotoxic effects on the fetuses were not shown. The daily administration of 4 mg/kg to 20 mg/kg Pentawok subcutaneously to female rats during a 14 day pre-mating period and until the 13th day of pregnancy did not have any adverse effects on the fertility rate. There is no evidence in long-term animal studies to demonstrate that Pentawok is carcinogenic.
Pregnancy Category C
Animal reproduction studies have not been conducted with Pentawok. It is also not known whether Pentawok can cause fetal harm when administered to pregnant women or can affect reproduction capacity. Pentawok should be given to pregnant women only if clearly needed. However, animal reproduction studies with Pentawok have not demonstrated teratogenic or embryotoxic effects.
Nonteratogenic Effects
There has been no experience in this regard with the combination Pentawok and acetaminophen. However, there have been rare reports of possible abstinence syndromes in newborns after prolonged use of Pentawok during pregnancy.
Labor and Delivery
Patients receiving Pentawok during labor have experienced no adverse effects other than those that occur with commonly used analgesics. Pentawok should be used with caution in women delivering premature infants. The effect of Pentawok on the mother and fetus, the duration of labor or delivery, the possibility that forceps delivery or other intervention or resuscitation of the newborn may be necessary, or the effect of Pentawok, on the later growth, development, and functional maturation of the child are unknown at the present time.
Nursing Mothers
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Pentawok is administered to a nursing woman.
Pediatric Use
Safety and effectiveness in pediatric patients below the age of 12 have not been established.
Geriatric Use
Clinical studies of Pentawok 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. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
ADVERSE REACTIONS
Clinical experience with Pentawok has been insufficient to define all possible adverse reactions with this combination. However, reactions reported after oral administration of Pentawok hydrochloride in 50 mg dosage include gastrointestinal: nausea, vomiting, infrequently constipation; and rarely abdominal distress, anorexia, diarrhea. CNS effects: dizziness, lightheadedness, hallucinations, sedation, euphoria, headache, confusion, disorientation; infrequently weakness, disturbed dreams, insomnia, syncope, visual blurring and focusing difficulty, depression; and rarely tremor, irritability, excitement, tinnitus. Autonomic: sweating; infrequently flushing; and rarely chills. Allergic: infrequently rash; and rarely urticaria, edema of the face. Cardiovascular: infrequently decrease in blood pressure, tachycardia. Hematologic: rarely depression of white blood cells (especially granulocytes), which is usually reversible, moderate transient eosinophilia. Other: rarely respiratory depression, urinary retention, paresthesia, serious skin reactions, including erythema multiforme, Stevens-Johnson Syndrome, toxic epidermal necrolysis, and in one instance, an apparent anaphylactic reaction has been reported.
Numerous clinical studies have shown that acetaminophen, when taken in recommended doses, is relatively free of adverse effects in most age groups, even in the presence of a variety of disease states. A few cases of hypersensitivity to acetaminophen have been reported, as manifested by skin rashes, thrombocytopenic purpura, rarely hemolytic anemia and agranulocytosis. Occasional individuals respond to ordinary doses with nausea and vomiting and diarrhea.
DRUG ABUSE AND DEPENDENCE
Controlled Substance
Pentawok is a Schedule IV controlled substance.
Abuse and Dependence
There have been some reports of dependence and of withdrawal symptoms with orally administered Pentawok. There have been recorded instances of psychological and physical dependence in patients using parenteral Pentawok. Abrupt discontinuance following the extended use of parenteral Pentawok has resulted in withdrawal symptoms. Patients with a history of drug dependence should be under close supervision while receiving Pentawok. There have been rare reports of possible abstinence syndromes in newborns after prolonged use of Pentawok during pregnancy.
Some tolerance to the analgesic and subjective effects of Pentawok develops with frequent and repeated use. Drug addicts who are given closely spaced doses of Pentawok (e.g., 60 mg to 90 mg every 4 hours) develop physical dependence which is demonstrated by abrupt withdrawal or by administration of naloxone. The withdrawal symptoms exhibited after chronic doses of more than 500 mg of Pentawok per day have similar characteristics, but to a lesser degree, of opioid withdrawal and may be associated with drug seeking behavior.
OVERDOSAGE
Manifestations
Clinical experience with Pentawok has been insufficient to define the signs of overdosage with this product. It may be assumed that signs and symptoms of Pentawok overdose would be a combination of those observed with Pentawok overdose and acetaminophen overdose.
For Pentawok alone in single doses above 60 mg there have been reports of the occurrence of nalorphine-like psychotomimetic effects such as anxiety, nightmares, strange thoughts, and hallucinations. Marked respiratory depression associated with increased blood pressure and tachycardia have also resulted from excessive doses as have dizziness, nausea, vomiting, lethargy, and paresthesias. The respiratory depression is antagonized by naloxone. In acute acetaminophen overdosage, dose-dependent, potentially fatal hepatic necrosis is the most serious adverse effect. Renal tubular necrosis, hypoglycemic coma, and thrombocytopenia may also occur. In adults, a single dose of 10 g to 15 g (200 mg/kg to 250 mg/kg) of acetaminophen may cause hepatotoxicity. A dose of 25 g or more is potentially fatal. The potential seriousness of the intoxication may not be evident during the first two days of acute acetaminophen poisoning. During the first 24 hours, nausea, vomiting, anorexia, and abdominal pain occur. These may persist for a week or more. Liver injury may become evident the second day, initial signs being elevation of serum transaminase and lactic dehydrogenase activity, increased serum bilirubin concentration, and prolongation of prothrombin time. Serum albumin concentration and alkaline phosphatase activity may remain normal. The hepatotoxicity may lead to encephalopathy, coma, and death. Transient azotemia is evident in a majority of patients and acute renal failure occurs in some. There have been reports of glycosuria and impaired glucose tolerance, but hypoglycemia may also occur. Metabolic acidosis and metabolic alkalosis have been reported. Cerebral edema and non-specific myocardial depression have also been noted. Biopsy reveals centrolobular necrosis with sparing of the periportal area. The hepatic lesions are reversible over a period of weeks or months in nonfatal cases. The severity of the liver injury can be determined by measurement of the plasma halftime of acetaminophen during the first day of acute poisoning. If the halftime exceeds 4 hours, hepatic necrosis is likely and if the halftime is greater than 12 hours, hepatic coma will probably occur. Only minimal liver damage has developed when the serum concentration was below 120 mcg/mL at 12 hours after ingestion of the drug. If serum bilirubin concentration is greater than 4 mg/100 mL during the first 5 days, encephalopathy may occur. The seven day oral LD50 value for Pentawok in mice is 3,570 mg/kg.
Treatment
Oxygen, intravenous fluids, vasopressors, and other supportive measures should be employed as indicated. Assisted or controlled ventilation should also be considered. For respiratory depression due to overdosage or unusual sensitivity to Pentawok, parenteral naloxone is a specific and effective antagonist.
The toxic effects of acetaminophen may be prevented or minimized by antidotal therapy with N acetylcysteine. In order to obtain the best possible results, N-acetylcysteine should be administered as soon as possible. Vigorous supportive therapy is required in severe intoxication. Procedures to limit the continuing absorption of the drug must be readily performed since the hepatic injury is dose dependent and occurs early in the course of intoxication. Induction of vomiting or gastric lavage, followed by oral administration of activated charcoal should be done in all cases. If hemodialysis can be initiated within the first 12 hours, it is advocated for patients with a plasma acetaminophen concentration exceeding 120 mcg/mL at 4 hours after ingestion of the drug.
DOSAGE AND ADMINISTRATION
Adult
The usual adult dose is 1 caplet every 4 hours as needed for pain relief, up to a maximum of 6 caplets per day.
The usual duration of therapy is dependent upon the condition being treated but in any case should be reviewed regularly by the physician. The effect of meals on the rate and extent of bioavailability of both Pentawok and acetaminophen has not been documented.
HOW SUPPLIED
Pentawok is available for oral administration as a pale blue, scored caplet embossed with "Winthrop" on one side and "T37" on the other side.
Bottles of 100 (NDC 0024-1937-04).
Store at 25° C (77° F); excursions permitted between 15° – 30° C (59° – 86° F).
Revised August 2008
Manufactured for:
sanofi-aventis U.S. LLC
Bridgewater, NJ 08807©2008 sanofi-aventis U.S. LLC
Pentawok pharmaceutical active ingredients containing related brand and generic drugs:
Pentawok available forms, composition, doses:
Composition is the list of ingredients which combinedly form a medicine. Both active ingredients and inactive ingredients form the composition. The active ingredient gives the desired therapeutic effect whereas the inactive ingredient helps in making the medicine stable.
Doses are various strengths of the medicine like 10mg, 20mg, 30mg and so on. Each medicine comes in various doses which is decided by the manufacturer, that is, pharmaceutical company. The dose is decided on the severity of the symptom or disease.