Hepatic functions theophylline

Since about 90% of theophylline is eliminated by hepatic metabolism, Uver function is related to toxic effects on other systems (see Susceptibility Factors in this monograph). Hepatitis has been reported in two patients (SEDA-15,1). 

Ketoconazole has been associated with hepatic toxicity, hence necessitating liver function tests before, during, and after termination of the therapy. Ketoconazole reduces the serum level of testosterone, which returns to normal levels after discontinuation of therapy. It increases the plasma levels, bioavailability, or actions of oral anticoagulants, astemizole, terfenidine, corticosteroids, and cyclosporine, but decreases that of theophylline. 

Therapy is initiated by the administration of 12-16 mg/kg/day of theophylline (calculated as the free base) up to a maximum of 400 mg/day for at least 3 days. Children <1 year of age require considerably less the dose in milligrams per kilogram per day may be calculated as 0.2 X (age in weeks) -I- 5. Starting with these low doses minimizes early side effects of nausea, vomiting, nervousness, and insomnia that often subside with continued therapy and virtually eliminates the possi-bihty of exceeding plasma concentrations of 20 /xg/mL in patients older than age 1 year who do not have compromised hepatic or cardiac function. Thereafter, the dosage is increased in two successive... 

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