The pharmacokinetics of the d and l enantiomers of sotalol are essentially identical.
Absorption
In healthy subjects, the oral bioavailability of sotalol is 90–100%. After oral administration, peak plasma concentrations are reached in 2.5 to 4 hours, and steady-state plasma concentrations are attained within 2–3 days (that is, after 5–6 doses when administered twice daily). Over the dosage range 160–640 mg/day sotalol displays dose proportionality with respect to plasma concentrations. When administered with a standard meal, the absorption of sotalol was reduced by approximately 20% compared to administration in fasting state.
Distribution
Sotalol does not bind to plasma proteins. Distribution occurs to a central (plasma) and to a peripheral compartment. Sotalol crosses the blood brain barrier poorly.
Metabolism
Sotalol is not metabolized and is not expected to inhibit or induce any CYP450 enzymes.
Excretion
Excretion of sotalol is predominantly via the kidney in the unchanged form, and therefore lower doses are necessary in conditions of renal impairment [
see Dosage and Administration (2.5)
]. The mean elimination half- life of sotalol is 12 hours. Dosing every 12 hours results in trough plasma concentrations which are approximately one-half of those at peak.
Specific Populations
Pediatric: The combined analysis of a single-dose study and a multiple-dose study with 59 children, aged between 3 days and 12 years, showed the pharmacokinetics of sotalol to be first order. A daily dose of 30 mg/m2 of sotalol was administered in the single dose study and daily doses of 30, 90 and 210 mg/m2 were administered every 8 hours in the multi-dose study. After rapid absorption with peak levels occurring on average between 2–3 hours following administration, sotalol was eliminated with a mean half-life of 9.5 hours.
Steady-state was reached after 1–2 days. The average peak to trough concentration ratio was 2. BSA was the most important covariate and more relevant than age for the pharmacokinetics of sotalol. The smallest children (BSA<0.33m2) exhibited a greater drug exposure (+59%) than the larger children who showed a uniform drug concentration profile. The intersubject variation for oral clearance was 22%.
Geriatric: Age does not significantly alter the pharmacokinetics of Sotalol Hydrochloride Tablets, but impaired renal function in geriatric patients can increase the terminal elimination half-life, resulting in increased drug accumulation.
Renal Impairment: Sotalol is mainly eliminated via the kidneys through glomerular filtration and to a small degree by tubular secretion. There is a direct relationship between renal function, as measured by serum creatinine or creatinine clearance, and the elimination rate of sotalol. The half-life of sotalol is prolonged (up to 69 hours) in anuric patients. Doses or dosing intervals should be adjusted based on creatinine clearance [
see Dosage and Administration (2.5)
].
Hepatic Impairment: Patients with hepatic impairment show no alteration in clearance of sotalol.
Drug-Drug Interactions:
Antacids: Administration of oral sotalol within 2 hours of antacids may result in a reduction in Cmax and AUC of 26% and 20%, respectively, and consequently in a 25% reduction in the bradycardic effect at rest.
Administration of the antacid two hours after oral sotalol has no effect on the pharmacokinetics or pharmacodynamics of sotalol.
No pharmacokinetic interactions were observed with hydrochlorothiazide or warfarin.