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DRUGS & SUPPLEMENTS
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Euphyllin 0.48advertisement
Euphyllin 0.48 uses
Euphyllin 0.48 Injection, USP 25 mg/mL Euphyllin 0.48, Dihydrate (Equivalent to 19.7 mg/mL of Anhydrous Theophylline) Ampul Fliptop Vial Rx only DESCRIPTIONEuphyllin 0.48 Injection, USP is a sterile, nonpyrogenic solution of Euphyllin 0.48 in water for injection. Euphyllin 0.48 (dihydrate) is approximately 79% of anhydrous theophylline by weight. Euphyllin 0.48 Injection is administered by slow intravenous injection or diluted and administered by intravenous infusion. The solution contains no bacteriostat or antimicrobial agent and is intended for use only as a single-dose injection. When smaller doses are required the unused portion should be discarded. Euphyllin 0.48 is a 2:1 complex of theophylline and ethylenediamine. Theophylline is structurally classified as a methylxanthine. Euphyllin 0.48 occurs as a white or slightly yellowish granule or powder, with a slight ammoniacal odor. Euphyllin 0.48 has the chemical name 1H-Purine-2, 6-dione, 3,7-dihydro-1,3-dimethyl-, compound with 1,2-ethanediamine (2:1). The structural formula of Euphyllin 0.48 (dihydrate) is as follows: The molecular formula of Euphyllin 0.48 dihydrate is C16H24N10O4 - 2(H2O) with a molecular weight of 456.46. Euphyllin 0.48 Injection, USP contains Euphyllin 0.48 (calculated as the dihydrate) 25 mg/mL (equivalent to 19.7 mg/mL anhydrous theophylline) prepared with the aid of ethylenediamine. The solution may contain an excess of ethylenediamine for pH adjustment. pH is 8.8 (8.6 to 9.0). The osmolar concentration is 0.17 mOsmol/mL (calc.). structural formula Euphyllin 0.48 advertisement
CLINICAL PHARMACOLOGYMechanism of Action:Theophylline has two distinct actions in the airways of patients with reversible obstruction; smooth muscle relaxation and suppression of the response of the airways to stimuli (i.e., nonbronchodilator prophylactic effects). While the mechanisms of action of theophylline are not known with certainty, studies in animals suggest that bronchodilation is mediated by the inhibition of two isozymes of phosphodiesterase (PDE III and, to a lesser extent, PDE IV), while nonbronchodilator prophylactic actions are probably mediated through one or more different molecular mechanisms, that do not involve inhibition of PDE III or antagonism of adenosine receptors. Some of the adverse effects associated with theophylline appear to be mediated by inhibition of PDE III (e.g., hypotension, tachycardia, headache, and emesis) and adenosine receptor antagonism (e.g., alterations in cerebral blood flow). Theophylline increases the force of contraction of diaphragmatic muscles. This action appears to be due to enhancement of calcium uptake through an adenosine-mediated channel. Serum Concentration-Effect Relationship: Bronchodilation occurs over the serum theophylline concentration range of 5 - 20 mcg/mL. Clinically important improvement in symptom control and pulmonary function has been found in most studies to require serum theophylline concentrations >10 mcg/mL. At serum theophylline concentrations >20 mcg/mL, both the frequency and severity of adverse reactions increase. In general, maintaining the average serum theophylline concentration between 10 and 15 mcg/mL will achieve most of the drug's potential therapeutic benefit while minimizing the risk of serious adverse events. Pharmacokinetics: It is, therefore, recommended that serum theophylline concentrations be measured frequently in acutely ill patients receiving intravenous theophylline (e.g., at 24-hr. intervals). More frequent measurements should be made during the initiation of therapy and in the presence of any condition that may significantly alter theophylline clearance (see PRECAUTIONS , Effects on Laboratory Tests ).
Note: In addition to the factors listed above, theophylline clearance is increased and half-life decreased by low carbohydrate/high protein diets, parenteral nutrition, and daily consumption of charcoal-broiled beef. A high carbohydrate/low protein diet can decrease the clearance and prolong the half-life of theophylline. Caffeine and 3-methylxanthine are the only theophylline metabolites with pharmacologic activity. 3-methylxanthine has approximately one tenth the pharmacologic activity of theophylline and serum concentrations in adults with normal renal function are <1 mcg/mL. In patients with end-stage renal disease, 3-methylxanthine may accumulate to concentrations that approximate the unmetabolized theophylline concentration. Caffeine concentrations are usually undetectable in adults regardless of renal function. In neonates, caffeine may accumulate to concentrations that approximate the unmetabolized theophylline concentration and thus, exert a pharmacologic effect. Both the N-demethylation and hydroxylation pathways of theophylline biotransformation are capacity-limited. Due to the wide intersubject variability of the rate of theophylline metabolism, nonlinearity of elimination may begin in some patients at serum theophylline concentrations <10 mcg/mL. Since this nonlinearity results in more than proportional changes in serum theophylline concentrations with changes in dose, it is advisable to make increases or decreases in dose in small increments in order to achieve desired changes in serum theophylline concentrations (See DOSAGE AND ADMINISTRATION , Table VI ). Accurate prediction of dose-dependency of theophylline metabolism in patients a priori is not possible, but patients with very high initial clearance rates (i.e., low steady state serum theophylline concentrations at above average doses) have the greatest likelihood of experiencing large changes in serum theophylline concentration in response to dosage changes. Clinical Studies:Inhaled beta-2 selective agonists and systemically administered corticosteroids are the treatments of first choice for management of acute exacerbations of asthma. The results of controlled clinical trials on the efficacy of adding intravenous theophylline to inhaled beta-2 selective agonists and systemically administered corticosteroids in the management of acute exacerbations of asthma have been conflicting. Most studies in patients treated for acute asthma exacerbations in an emergency department have shown that addition of intravenous theophylline does not produce greater bronchodilation and increases the risk of adverse effects. In contrast, other studies have shown that addition of intravenous theophylline is beneficial in the treatment of acute asthma exacerbations in patients requiring hospitalization, particularly in patients who are not responding adequately to inhaled beta-2 selective agonists. In patients with chronic obstructive pulmonary disease (COPD), clinical studies have shown that theophylline decreases dyspnea, air trapping, the work of breathing, and improves contractility of diaphragmatic muscles with little or no improvement in pulmonary function measurements. advertisement
INDICATIONS AND USAGEIntravenous theophylline is indicated as an adjunct to inhaled beta-2 selective agonists and systemically administered corticosteroids for the treatment of acute exacerbations of the symptoms and reversible airflow obstruction associated with asthma and other chronic lung diseases, e.g., emphysema and chronic bronchitis. CONTRAINDICATIONSEuphyllin 0.48 is contraindicated in patients with a history of hypersensitivity to theophylline or other components in the product including ethylenediamine. WARNINGSConcurrent Illness:Theophylline should be used with extreme caution in patients with the following clinical conditions due to the increased risk of exacerbation of the concurrent condition: Active peptic ulcer disease Seizure disorders Cardiac arrhythmias Conditions That Reduce Theophylline Clearance:There are several readily identifiable causes of reduced theophylline clearance. Age Neonates (term and premature) Children <1 year Elderly (>60 years) Concurrent Diseases Acute pulmonary edema Congestive heart failure Cor pulmonale Fever; ≥102° for 24 hours or more; or lesser temperature elevations for longer periods Hypothyroidism Liver disease; cirrhosis, acute hepatitis Reduced renal function in infants <3 months of age Sepsis with multi-organ failure Shock Cessation of Smoking Drug Interactions Adding a drug that inhibits theophylline metabolism (e.g., cimetidine, erythromycin, tacrine) or stopping a concurrently administered drug that enhances theophylline metabolism (e.g., carbamazepine, rifampin). (See PRECAUTIONS , Drug Interactions, Table II .) When Signs or Symptoms of Theophylline Toxicity Are Present: |
Drug | Type Of Interaction | Effect** |
---|---|---|
* Refer to PRECAUTIONS , Drug Interactions for further information regarding table. ** Average effect on steady-state theophylline concentration or other clinical effect for pharmacologic interactions. Individual patients may experience larger changes in serum theophylline concentration than the value listed. | ||
Adenosine | Theophylline blocks adenosine receptors. | Higher doses of adenosine may be required to achieve desired effect. |
Alcohol | A single large dose of alcohol (3 mL/kg of whiskey) decreases theophylline clearance for up to 24 hours. | 30% increase |
Allopurinol | Decreases theophylline clearance at allopurinol doses ≥600 mg/day. | 25% increase |
Aminoglutethimide | Increases theophylline clearance by induction of microsomal enzyme activity. | 25% decrease |
Carbamazepine | Similar to aminoglutethimide. | 30% decrease |
Cimetidine | Decreases theophylline clearance by inhibiting cytochrome P450 1A2. | 70% increase |
Ciprofloxacin | Similar to cimetidine. | 40% increase |
Clarithromycin | Similar to erythromycin. | 25% increase |
Diazepam | Benzodiazepines increase CNS concentrations of adenosine, a potent CNS depressant, while theophylline blocks adenosine receptors. | Larger diazepam doses may be required to produce desired level of sedation. Discontinuation of theophylline without reduction of diazepam dose may result in respiratory depression. |
Disulfiram | Decreases theophylline clearance by inhibiting hydroxylation and demethylation. | 50% increase |
Enoxacin | Similar to cimetidine. | 300% increase |
Ephedrine | Synergistic CNS effects. | Increased frequency of nausea, nervousness, and insomnia. |
Erythromycin | Erythromycin metabolite decreases theophylline clearance by inhibiting cytochrome P450 3A3. | 35% increase. Erythromycin steady-state serum concentrations decrease by a similar amount. |
Estrogen | Estrogen containing oral contraceptives decrease theophylline clearance in a dose-dependent fashion. The effect of progesterone on theophylline clearance is unknown. | 30% increase |
Flurazepam | Similar to diazepam. | Similar to diazepam. |
Fluvoxamine | Similar to cimetidine. | Similar to cimetidine. |
Halothane | Halothane sensitizes the myocardium to catecholamines, theophylline increases release of endogenous catecholamines. | Increased risk of ventricular arrhythmias. |
Interferon, human recombinant alpha-A | Decreases theophylline clearance. | 100% increase |
Isoproterenol (I.V.) | Increases theophylline clearance. | 20% decrease |
Ketamine | Pharmacologic | May lower theophylline seizure threshold. |
Lithium | Theophylline increases renal lithium clearance. | Lithium dose required to achieve a therapeutic serum concentration increased an average of 60%. |
Lorazepam | Similar to diazepam. | Similar to diazepam. |
Methotrexate (MTX) | Decreases theophylline clearance. | 20% increase after low dose MTX, higher dose MTX may have a greater effect. |
Mexiletine | Similar to disulfiram. | 80% increase |
Midazolam | Similar to diazepam. | Similar to diazepam. |
Moricizine | Increases theophylline clearance. | 25% decrease |
Pancuronium | Theophylline may antagonize nondepolarizing neuromuscular blocking effects; possibly due to phosphodiesterase inhibition. | Larger dose of pancuronium may be required to achieve neuromuscular blockade. |
Pentoxifylline | Decreases theophylline clearance. | 30% increase |
Phenobarbital (PB) | Similar to aminoglutethimide. | 25% decrease after two weeks of concurrent Phenobarbital. |
Phenytoin | Phenytoin increases theophylline clearance by increasing microsomal enzyme activity. Theophylline decreases phenytoin absorption. | Serum theophylline and phenytoin concentrations decrease about 40%. |
Propafenone | Decreases theophylline clearance and pharmacologic interaction. | 40% increase. Beta-2 blocking effect may decrease efficacy of theophylline. |
Propranolol | Similar to cimetidine and pharmacologic interaction. | 100% increase. Beta-2 blocking effect may decrease efficacy of theophylline. |
Rifampin | Increases theophylline clearance by increasing cytochrome P450 1A2 and 3A3 activity. | 20 - 40% decrease |
Sulfinpyrazone | Increases theophylline clearance by increasing demethylation and hydroxylation. Decreases renal clearance of theophylline. | 20% decrease |
Tacrine | Similar to cimetidine, also increases renal clearance of theophylline. | 90% increase |
Thiabendazole | Decreases theophylline clearance. | 190% increase |
Ticlopidine | Decreases theophylline clearance. | 60% increase |
Troleandomycin | Similar to erythromycin. | 33 - 100% increase depending on troleandomycin dose. |
Verapamil | Similar to disulfiram. | 20% increase |
albuterol, systemic and inhaled amoxicillin ampicillin, with or without sulbactam atenolol azithromycin caffeine, dietary ingestion cefaclor co-trimoxazole (trimethoprim and sulfamethoxazole) diltiazem dirithromycin enflurane famotidine felodipine finasteride hydrocortisone isoflurane isoniazid isradipine influenza vaccine ketoconazole | lomefloxacin mebendazole medroxyprogesterone methylprednisolone metronidazole metoprolol nadolol nifedipine nizatidine norfloxacin ofloxacin omeprazole prednisone, prednisolone ranitidine rifabutin roxithromycin sorbitol (purgative doses do not inhibit theophylline absorption) sucralfate terbutaline, systemic terfenadine tetracycline tocainide |
The Effect of Other Drugs on Theophylline Serum Concentration Measurements:
Most serum theophylline assays in clinical use are immunoassays which are specific for theophylline. Other xanthines such as caffeine, dyphylline, and pentoxifylline are not detected by these assays. Some drugs (e.g., cefazolin, cephalothin), however, may interfere with certain HPLC techniques. Caffeine and xanthine metabolites in neonates or patients with renal dysfunction may cause the reading from some dry reagent office methods to be higher than the actual serum theophylline concentration.
Long term carcinogenicity studies have been carried out in mice (oral doses 30 - 150 mg/kg) and rats (oral doses 5 - 75 mg/kg). Results are pending.
Theophylline has been studied in Ames salmonella, in vivo and in vitro cytogenetics, micronucleus and Chinese hamster ovary test systems and has not been shown to be genotoxic.
In a 14 week continuous breeding study, theophylline, administered to mating pairs of B6C3F1 mice at oral doses of 120, 270 and 500 mg/kg (approximately 1.0 - 3.0 times the human dose on a mg/m2 basis) impaired fertility, as evidenced by decreases in the number of live pups per litter, decreases in the mean number of litters per fertile pair, and increases in the gestation period at the high dose as well as decreases in the proportion of pups born alive at the mid and high dose. In 13 week toxicity studies, theophylline was administered to F344 rats and B6C3F1 mice at oral doses of 40 - 300 mg/kg (approximately 2 times the human dose on a mg/m2 basis). At the high dose, systemic toxicity was observed in both species including decreases in testicular weight.
Category C: There are no adequate and well controlled studies in pregnant women. Additionally, there are no teratogenicity studies in nonrodents. Theophylline was not shown to be teratogenic in CD-1 mice at oral doses up to 400 mg/kg, approximately 2.0 times the human dose on a mg/m2 basis or in CD-1 rats at oral doses up to 260 mg/kg, approximately 3.0 times the recommended human dose on a mg/m2 basis. At a dose of 220 mg/kg, embryotoxicity was observed in rats in the absence of maternal toxicity.
Theophylline is excreted into breast milk and may cause irritability or other signs of mild toxicity in nursing human infants. The concentration of theophylline in breast milk is about equivalent to the maternal serum concentration. An infant ingesting a liter of breast milk containing 10 - 20 mcg/mL of theophylline per day is likely to receive 10 - 20 mg of theophylline per day. Serious adverse effects in the infant are unlikely unless the mother has toxic serum theophylline concentrations.
Theophylline is safe and effective for the approved indications in pediatric patients. The constant infusion rate of intravenous theophylline must be selected with caution in pediatric patients since the rate of theophylline clearance is highly variable across the age range of neonates to adolescents (see CLINICAL PHARMACOLOGY , Table I , WARNINGS , and DOSAGE AND ADMINISTRATION , Table V ). Due to the immaturity of theophylline metabolic pathways in pediatric patients under the age of one year, particular attention to dosage selection and frequent monitoring of serum theophylline concentrations are required when theophylline is prescribed to pediatric patients in this age group.
Elderly patients are at significantly greater risk of experiencing serious toxicity from theophylline than younger patients due to pharmacokinetic and pharmacodynamic changes associated with aging. Theophylline clearance is reduced in patients greater than 60 years of age, resulting in increased serum theophylline concentrations in response to a given theophylline infusion rate. Protein binding may be decreased in the elderly resulting in a larger proportion of the total serum theophylline concentration in the pharmacologically active unbound form. Elderly patients also appear to be more sensitive to the toxic effects of theophylline after chronic overdosage than younger patients. For these reasons, the maximum infusion rate of theophylline in patients greater than 60 years of age ordinarily should not exceed 17 mg/hr (21 mg/hr as Euphyllin 0.48) unless the patient continues to be symptomatic and the peak steady state serum theophylline concentration is <10 mcg/mL (see DOSAGE AND ADMINISTRATION ). Theophylline infusion rates greater than 17 mg/hr (21 mg/hr as Euphyllin 0.48) should be prescribed with caution in elderly patients.
Adverse reactions associated with theophylline are generally mild when peak serum theophylline concentrations are <20 mcg/mL and mainly consist of transient caffeine-like adverse effects such as nausea, vomiting, headache, and insomnia. When peak serum theophylline concentrations exceed 20 mcg/mL, however, theophylline produces a wide range of adverse reactions including persistent vomiting, cardiac arrhythmias, and intractable seizures which can be lethal (see OVERDOSAGE ).
Other adverse reactions that have been reported at serum theophylline concentrations <20 mcg/mL include diarrhea, irritability, restlessness, fine skeletal muscle tremors, and transient diuresis. In patients with hypoxia secondary to COPD, multifocal atrial tachycardia and flutter have been reported at serum theophylline concentrations ≥15 mcg/mL. There have been a few isolated reports of seizures at serum theophylline concentrations <20 mcg/mL in patients with an underlying neurological disease or in elderly patients. The occurrence of seizures in elderly patients with serum theophylline concentrations <20 mcg/mL may be secondary to decreased protein binding resulting in a larger proportion of the total serum theophylline concentration in the pharmacologically active unbound form. The clinical characteristics of the seizures reported in patients with serum theophylline concentrations <20 mcg/mL have generally been milder than seizures associated with excessive serum theophylline concentrations resulting from an overdose (i.e., they have generally been transient, often stopped without anticonvulsant therapy, and did not result in neurological residua).
Products containing Euphyllin 0.48 may rarely produce severe allergic reactions of the skin, including exfoliative dermatitis, after systemic administration in a patient who has been previously sensitized by topical application of a substance containing ethylenediamine. In such patients skin patch tests are positive for ethylenediamine, a component of Euphyllin 0.48, and negative for theophylline. Pharmacists and other individuals who experience repeated skin exposure while physically handling Euphyllin 0.48 may develop a contact dermatitis due to the ethylenediamine component.
* These data are derived from two studies in patients with serum theophylline concentrations >30 mcg/mL. In the first study (Study #1 – Shanon, Ann Intern Med 1993;119:1161-67), data were prospectively collected from 249 consecutive cases of theophylline toxicity referred to a regional poison center for consultation. In the second study (Study #2 – Sessler, Am J Med 1990; 88:567-76), data were retrospectively collected from 116 cases with serum theophylline concentrations >30 mcg/mL among 6000 blood samples obtained for measurement of serum theophylline concentrations in three emergency departments. Differences in the incidence of manifestations of theophylline toxicity between the two studies may reflect sample selection as a result of study design (e.g., in Study #1, 48% of the patients had acute intoxications versus only 10% in Study #2) and different methods of reporting results. ** NR = Not reported in a comparable manner. | ||||||||
Acute Overdose (Large Single Ingestion) | Chronic Overdosage (Multiple Excessive Doses) | |||||||
Sign/Symptom | Study 1 (n=157) | Study 2 (n=14) | Study 1 (n=92) | Study 2 (n=102) | ||||
Asymptomatic | NR** | 0 | NR** | 6 | ||||
Gastrointestinal | ||||||||
Vomiting | 73 | 93 | 30 | 61 | ||||
Abdominal pain | NR** | 21 | NR** | 12 | ||||
Diarrhea | NR** | 0 | NR** | 14 | ||||
Hematemesis | NR** | 0 | NR** | 2 | ||||
Metabolic/Other | ||||||||
Hypokalemia | 85 | 79 | 44 | 43 | ||||
Hyperglycemia | 98 | NR** | 18 | NR** | ||||
Acid/base disturbance | 34 | 21 | 9 | 5 | ||||
Rhabdomyolysis | NR** | 7 | NR** | 0 | ||||
Cardiovascular | ||||||||
Sinus tachycardia | 100 | 86 | 100 | 62 | ||||
Other supraventricular | 2 | 21 | 12 | 14 | ||||
tachycardias | ||||||||
Ventricular premature beats | 3 | 21 | 10 | 19 | ||||
Atrial fibrillation or flutter | 1 | NR** | 12 | NR** | ||||
Multifocal atrial tachycardia | 0 | NR** | 2 | NR** | ||||
Ventricular arrhythmias with | 7 | 14 | 40 | 0 | ||||
hemodynamic instability | ||||||||
Hypotension/shock | NR** | 21 | NR** | 8 | ||||
Neurologic | ||||||||
Nervousness | NR** | 64 | NR** | 21 | ||||
Tremors | 38 | 29 | 16 | 14 | ||||
Disorientation | NR** | 7 | NR** | 11 | ||||
Seizures | 5 | 14 | 14 | 5 | ||||
Death | 3 | 21 | 10 | 4 |
The chronicity and pattern of theophylline overdosage significantly influences clinical manifestations of toxicity, management and outcome. There are two common presentations: 1) acute overdose, i.e., infusion of an excessive loading dose or excessive maintenance infusion rate for less than 24 hours, and 2) chronic overdosage, i.e., excessive maintenance infusion rate for greater than 24 hours. The most common causes of chronic theophylline overdosage include clinician prescribing of an excessive dose or a normal dose in the presence of factors known to decrease the rate of theophylline clearance and increasing the dose in response to an exacerbation of symptoms without first measuring the serum theophylline concentration to determine whether a dose increase is safe.
Several studies have described the clinical manifestations of theophylline overdose following oral administration and attempted to determine the factors that predict life-threatening toxicity. In general, patients who experience an acute overdose are less likely to experience seizures than patients who have experienced a chronic overdosage, unless the peak serum theophylline concentration is >100 mcg/mL. After a chronic overdosage, generalized seizures, life-threatening cardiac arrhythmias, and death may occur at serum theophylline concentrations >30 mcg/mL. The severity of toxicity after chronic overdosage is more strongly correlated with the patient's age than the peak serum theophylline concentration; patients >60 years are at the greatest risk for severe toxicity and mortality after a chronic overdosage. Pre-existing or concurrent disease may also significantly increase the susceptibility of a patient to a particular toxic manifestation, e.g., patients with neurologic disorders have an increased risk of seizures and patients with cardiac disease have an increased risk of cardiac arrhythmias for a given serum theophylline concentration compared to patients without the underlying disease.
The frequency of various reported manifestations of oral theophylline overdose according to the mode of overdose are listed in Table IV .
Other manifestations of theophylline toxicity include increases in serum calcium, creatine kinase, myoglobin and leukocyte count, decreases in serum phosphate and magnesium, acute myocardial infarction, and urinary retention in men with obstructive uropathy.
Seizures associated with serum theophylline concentrations >30 mcg/mL are often resistant to anticonvulsant therapy and may result in irreversible brain injury if not rapidly controlled. Death from theophylline toxicity is most often secondary to cardiorespiratory arrest and/or hypoxic encephalopathy following prolonged generalized seizures or intractable cardiac arrhythmias causing hemodynamic compromise.
Specific Recommendations:
Increasing the rate of theophylline clearance by extracorporeal methods may rapidly decrease serum concentrations, but the risks of the procedure must be weighed against the potential benefit. Charcoal hemoperfusion is the most effective method of extracorporeal removal, increasing theophylline clearance up to six fold, but serious complications, including hypotension, hypocalcemia, platelet consumption and bleeding diatheses may occur. Hemodialysis is about as efficient as multiple-dose oral activated charcoal and has a lower risk of serious complications than charcoal hemoperfusion. Hemodialysis should be considered as an alternative when charcoal hemoperfusion is not feasible and multiple-dose oral charcoal is ineffective because of intractable emesis. Serum theophylline concentrations may rebound 5 - 10 mcg/mL after discontinuation of charcoal hemoperfusion or hemodialysis due to redistribution of theophylline from the tissue compartment. Peritoneal dialysis is ineffective for theophylline removal; exchange transfusions in neonates have been minimally effective.
General Considerations:
The steady-state serum theophylline concentration is a function of the infusion rate and the rate of theophylline clearance in the individual patient. Because of marked individual differences in the rate of theophylline clearance, the dose required to achieve a serum theophylline concentration in the 10-20 mcg/mL range varies fourfold among otherwise similar patients in the absence of factors known to alter theophylline clearance. For a given population there is no single theophylline dose that will provide both safe and effective serum concentrations for all patients. Administration of the median theophylline dose required to achieve a therapeutic serum theophylline concentration in a given population may result in either sub-therapeutic or potentially toxic serum theophylline concentrations in individual patients.
When theophylline is used as an acute bronchodilator, the goal of obtaining a therapeutic serum concentration is best accomplished with an intravenous loading dose. Because of rapid distribution into body fluids, the serum concentration (C) obtained from an initial loading dose (LD) is related primarily to the volume of distribution (V), the apparent space into which the drug diffuses:
C = LD/V
If a mean volume of distribution of about 0.5 L/kg is assumed (actual range is 0.3 to 0.7 L/kg), each mg/kg (ideal body weight) of theophylline administered as a loading dose over 30 minutes results in an average 2 mcg/mL increase in serum theophylline concentration. Therefore, in a patient who has received no theophylline in the previous 24 hours, a loading dose of intravenous theophylline of 4.6 mg/kg (5.7 mg/kg as Euphyllin 0.48), calculated on the basis of ideal body weight and administered over 30 minutes, on average, will produce a maximum post-distribution serum concentration of 10 mcg/mL with a range of 6-16 mcg/mL. When a loading dose becomes necessary in the patient who has already received theophylline, estimation of the serum concentration based upon the history is unreliable, and an immediate serum level determination is indicated. The loading dose can then be determined as follows:
D = (Desired C - Measured C) (V)
where D is the loading dose, C is the serum theophylline concentration, and V is the volume of distribution. The mean volume of distribution can be assumed to be 0.5 L/kg and the desired serum concentration should be conservative (e.g., 10 mcg/mL) to allow for the variability in the volume of distribution.
A serum concentration obtained 30 minutes after an intravenous loading dose, when distribution is complete, can be used to assess the need for and size of subsequent loading doses, if clinically indicated, and for guidance of continuing therapy. Once a serum concentration of 10 to 15 mcg/mL has been achieved with the use of a loading dose(s), a constant intravenous infusion is started. The rate of administration is based upon mean pharmacokinetic parameters for the population and calculated to achieve a target serum concentration of 10 mcg/mL (see Table V ). For example, in non-smoking adults, initiation of a constant intravenous theophylline infusion of 0.4 mg/kg/hr (0.5 mg/kg/hr as Euphyllin 0.48) at the completion of the loading dose, on average, will result in a steady-state concentration of 10 mcg/mL with a range of 7-26 mcg/mL. The mean and range of steady-state serum concentrations are similar when the average child (age 1 to 9 years) is given a loading dose of 4.6 mg/kg theophylline (5.7 mg/kg as Euphyllin 0.48) followed by a constant intravenous infusion of 0.8 mg/kg/hr (1.0 mg/kg/hr as Euphyllin 0.48). Since there is large interpatient variability in theophylline clearance, serum concentrations will rise or fall when the patient's clearance is significantly different from the mean population value used to calculate the initial infusion rate. Therefore, a second serum concentration should be obtained one expected half-life after starting the constant infusion (e.g., approximately 4 hours for children age 1 to 9 and 8 hours for nonsmoking adults; See Table I for the expected half-life in additional patient populations) to determine if the concentration is accumulating or declining from the post loading dose level. If the level is declining as a result of a higher than average clearance, an additional loading dose can be administered and/or the infusion rate increased. In contrast, if the second sample demonstrates a higher level, accumulation of the drug can be assumed, and the infusion rate should be decreased before the concentration exceeds 20 mcg/mL. An additional sample is obtained 12 to 24 hours later to determine if further adjustments are required and then at 24-hour intervals to adjust for changes, if they occur. This empiric method, based upon mean pharmacokinetic parameters, will prevent large fluctuations in serum concentration during the most critical period of the patient's course.
In patients with cor pulmonale, cardiac decompensation, or liver dysfunction, or in those taking drugs that markedly reduce theophylline clearance (e.g., cimetidine), the initial theophylline infusion rate should not exceed 17 mg/hr (21 mg/hr as Euphyllin 0.48) unless serum concentrations can be monitored at 24-hour intervals. In these patients, 5 days may be required before steady-state is reached.
Theophylline distributes poorly into body fat, therefore, mg/kg dose should be calculated on the basis of ideal body weight.
Table V contains initial theophylline infusion rates following an appropriate loading dose recommended for patients in various age groups and clinical circumstances. Table VI contains recommendations for final theophylline dosage adjustment based upon serum theophylline concentrations.
* To achieve a target concentration of 10 mcg/mL Aminophylline=theophylline/0.8. Use ideal body weight for obese patients. † Lower initial dosage may be required for patients receiving other drugs that decrease theophylline clearance (e.g., cimetidine). ‡ To achieve a target concentration of 7.5 mcg/mL for neonatal apnea. § Not to exceed 900 mg/day, unless serum levels indicate the need for a larger dose. ı Not to exceed 400 mg/day, unless serum levels indicate the need for a larger dose. | ||
Patient population | Age | Theophylline infusion rate (mg/kg/hr)*† |
Neonates | Postnatal age up to 24 days Postnatal age beyond 24 days | 1 mg/kg q12h/‡ 1.5 mg/kg q12h/‡ |
Infants | 6-52 weeks old | mg/kg/hr= (0.008)(age in weeks) + 0.21 |
Young children | 1-9 years | 0.8 |
Older children | 9-12 years | 0.7 |
Adolescents (cigarette or marijuana smokers) | 12-16 years | 0.7 |
Adolescents (nonsmokers) | 12-16 years | 0.5 § |
Adults (otherwise healthy nonsmokers) | 16-60 years | 0.4 § |
Elderly | >60 years | 0.3 ı |
Cardiac decompensation, cor pulmonale, liver dysfunction, sepsis with multiorgan failure, or shock | 0.2 ı |
¶ Dose reduction and/or serum theophylline concentration measurement is indicated whenever adverse effects are present, physiologic abnormalities that can reduce theophylline clearance occur (e.g., sustained fever), or a drug that interacts with theophylline is added or discontinued (see WARNINGS ). | ||||
Peak Serum Concentration | Dosage Adjustment | |||
<9.9 mcg/mL | If symptoms are not controlled and current dosage is tolerated, increase infusion rate about 25%. Recheck serum concentration after 12 hours in children and 24 hours in adults for further dosage adjustment. | |||
10 to 14.9 mcg/mL | If symptoms are controlled and current dosage is tolerated, maintain infusion rate and recheck serum concentration at 24 hour intervals.¶ If symptoms are not controlled and current dosage is tolerated consider adding additional medication(s) to treatment regimen. | |||
15-19.9 mcg/mL | Consider 10% decrease in infusion rate to provide greater margin of safety even if current dosage is tolerated.¶ | |||
20-24.9 mcg/mL | Decrease infusion rate by 25% even if no adverse effects are present. Recheck serum concentration after 12 hours in children and 24 hours in adults to guide further dosage adjustment. | |||
25-30 mcg/mL | Stop infusion for 12 hours in children and 24 hours in adults and decrease subsequent infusion rate at least 25% even if no adverse effects are present. Recheck serum concentration after 12 hours in children and 24 hours in adults to guide further dosage adjustment. If symptomatic, stop infusion and consider whether overdose treatment is indicated. | |||
>30 mcg/mL | Stop the infusion and treat overdose as indicated. If theophylline is subsequently resumed, decrease infusion rate by at least 50% and recheck serum concentration after 12 hours in children and 24 hours in adults to guide further dosage adjustment. |
Intravenous Admixture Incompatibility:
Although there have been reports of Euphyllin 0.48 precipitating in acidic media, these reports do not apply to the dilute solutions found in intravenous infusions. Euphyllin 0.48 injection should not be mixed in a syringe with other drugs but should be added separately to the intravenous solution.
When an intravenous solution containing Euphyllin 0.48 is given "piggyback", the intravenous system already in place should be turned off while the Euphyllin 0.48 is infused if there is a potential problem with admixture incompatibility.
Because of the alkalinity of Euphyllin 0.48 containing solutions, drugs known to be alkali labile should be avoided in admixtures. These include epinephrine HCl, norepinephrine bitartrate, isoproterenol HCl and penicillin G potassium. It is suggested that specialized literature be consulted before preparing admixtures with Euphyllin 0.48 and other drugs.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Do not administer unless solution is clear and container is undamaged. Discard unused portion. Do not use if crystals have separated from solution.
Euphyllin 0.48 Injection, USP 25 mg/mL is supplied in single-dose containers as follows:
NDC No. | Container | Volume | Total Content |
0409-7385-01 | Ampul | 10 mL | 250 mg |
0409-7386-01 | Ampul | 20 mL | 500 mg |
0409-5921-01 | Partial-fill Fliptop Vial | 10 mL | 250 mg |
0409-5922-01 | Partial-fill Fliptop Vial | 20 mL | 500 mg |
Store at 20 to 25°C (68 to 77°F).
PROTECT FROM LIGHT. Store in carton until time of use.
SINGLE-DOSE CONTAINER. Discard unused portion.
Revised: November, 2009
Printed in USA EN-2301
Hospira, Inc., Lake Forest, IL 60045 USA
Hospira logo
10 mL Single-dose
Euphyllin 0.48
Inj., USP
250 mg (25 mg/mL)
Protect from light.
Do not use if crystals have
separated from solution.
HOSPIRA, INC., LAKE FOREST, IL 60045 USA
Rx only
10 mL Single-dose Ampul
25/NDC 0409-7385-01
Euphyllin 0.48
Injection, USP
250 mg (25 mg/mL)
Protect from light.
Each mL contains Euphyllin 0.48 (calculated as the dihydrate) 25 mg
(equivalent to 19.7 mg/mL of anhydrous theophylline). May contain an
excess of ethylenediamine for pH adjustment. pH 8.8 (8.6 to 9.0).
Sterile, nonpyrogenic. Protect from light by retaining in carton until ready
for use. Do not use if crystals have separated from solution.
For I.V. use. Usual dose: See insert. Store at controlled room temperature
15° to 30°C (59° to 86°F).
©Hospira 2004
RL-0277 (6/04)
Printed in USA
HOSPIRA, INC., LAKE FOREST, IL 60045 USA
Rx only
Hospira
20 mL
Single-dose
Ampul
Euphyllin 0.48
Inj., USP
500 mg (25 mg/mL)
Protect from light.
DO NOT USE IF CRYSTALS HAVE
SEPARATED FROM SOLUTION.
HOSPIRA, INC., LAKE FOREST, IL 60045 USA
Rx only
20 mL Single-dose Ampul
25/NDC 0409-7386-01
Rx only
Euphyllin 0.48
Injection, USP
500 mg (25 mg/mL)
Protect from light.
Each mL contains Euphyllin 0.48 (calculated as the dihydrate) 25 mg
(equivalent to 19.7 mg/mL of anhydrous theophylline). May contain an
excess of ethylenediamine for pH adjustment. pH 8.8 (8.6 to 9.0).
Headspace nitrogen gassed. Sterile, nonpyrogenic. Protect from light
by retaining in carton until ready for use. Do not use if crystals have
separated from solution. For I.V. use. Usual dose: See insert. Store at
20 to 25°C (68 to 77°F).
Printed in USA
RL-3070
Hospira, Inc., Lake Forest, IL 60045 USA
Hospira
10 mL Single-dose
Euphyllin 0.48
Injection, USP
250 mg (25 mg/mL)
Protect from light.
DO NOT USE IF CRYSTALS HAVE
SEPARATED FROM SOLUTION.
HOSPIRA, INC., LAKE FOREST, IL 60045 USA
Rx only
Depending on the reaction of the Euphyllin 0.48 after taken, if you are feeling dizziness, drowsiness or any weakness as a reaction on your body, Then consider Euphyllin 0.48 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 Euphyllin 0.48 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. Arunabha Ray, MD Pharmacology
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