In an open pilot study, 12 children with tinea capitis were treated for 6 weeks with oral terbinafine (125 mg/day), and followed up 2 weeks later. The study was conducted to evaluate the efficacy, safety and pharmacokinetics of terbinafine. All patients were completely cured at the end of the treatment period, and there was no evidence of relapse at follow-up. Seven had a negative culture after 3 weeks of treatment. The time to obtain culture conversion from positive to negative did not appear to be related to body weight, but to clinical severity at baseline. Terbinafine is well tolerated and safe over a 56-day period. The kinetic data show a higher clearance of terbinafine in children compared with adults, with shorter alpha- and beta-phase elimination half-lives. However, a longer terminal gamma-phase (at least 6 days) is observed, as in adults, after multiple dose administration, and this is related to elimination from the tissues. The plasma concentrations are comparable between children and adults at a steady state (125 mg/day).

These results show the reliability and reproducibility of this route of dihydroergotamine administration adapted for the treatment of migraine headaches.

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The dose-dependency of the pharmacokinetic parameters of terbinafine and its N-demethyl derivative was investigated in a randomized four-way crossover study in healthy volunteers following single oral administrations of 125, 250, 500 and 750 mg of terbinafine. Plasma concentrations of terbinafine and its metabolite were measured by a validated high-performance liquid chromatography (HPLC) method using ultraviolet detection. Concentration data were fitted to a two-compartment model. The relationship between Cmax or the area under the concentration curve (AUC) and the terbinafine dose was analysed by classical linear regression. Terbinafine disposition parameters were dose-independent, with the exception of Tmax and t1/2 alpha, which were prolonged with the 500- and 750-mg doses. The terbinafine Cmax and AUC, however, were linear and dose-proportional over the entire dose range. The N-demethylated metabolite appeared in plasma at the same time as terbinafine and showed similar prolongations in Tmax and t1/2 alpha with the 500- and 750-mg doses. In addition, the Cmax deviated from proportionality at these doses, giving values 22% lower than projected, while the AUC was linear and dose-proportional over the whole range of doses. The slight disproportionality in the dispositions of terbinafine and its N-demethyl metabolite at 500 and 750 mg are not expected to be clinically significant.

The plasma pharmacokinetics, and the urinary excretion, of terbinafine and its five main metabolites have been investigated after a single oral dose administration of 125 mg to 16 healthy subjects. In plasma, the highest concentrations are observed for the two carboxybutyl metabolites, with a predominance for the carboxybutylterbinafine. For this metabolite, as compared to terbinafine, the Cmax and AUC are 2.4 and 13 times higher respectively. The demethylterbinafine presents a plasma profile close to that of terbinafine. The two hydroxy metabolites are only found as glucuronide and are of minor importance. The apparent terminal half-lives of terbinafine, demethylterbinafine, and the two carboxy metabolites appear to be similar (approximately 25 h). As compared to the plasma concentration of total radioactivity observed after a single oral administration of the same dose of 14C-terbinafine, the parent drug and these five metabolites, account for more than 80% of the total radioactivity in plasma over the 0-48 h interval following administration. In urine, the major metabolite is demethylcarboxybutylterbinafine, which amounted to about 10% of the administered dose. Terbinafine and demethylterbinafine are only excreted as trace amounts in urine. Carboxybutylterbinafine and the two hydroxy metabolites are excreted in the range of 0.5-2% either as glucuronides or free. Urinary excretion over the 0-48 h interval of terbinafine and of the five metabolites amounted to about 14% of the administered dose. This is far below the level of total radioactivity measured in urine over the same interval (approximately 57%), after administration of 14C-terbinafine. This shows in contrast to plasma, that numerous other metabolites are present in urine.

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Based on the wide therapeutic dosage ranges of valsartan and simvastatin, and the highly variable pharmacokinetics of three analytes, the observed differences in the exposure and C(max) of valsartan, simvastatin beta-hydroxy acid and simvastatin in the combination treatment are unlikely to be of clinical relevance.