Bioequivalence of quinidine in two sustained-release preparations

Area of Science:

• Pharmacokinetics
• Drug Formulation
• Clinical Pharmacology

Background:

• Sustained-release quinidine bisulphate is widely prescribed, but dosing is often incorrect.
• Understanding the bioequivalence of different formulations is crucial for therapeutic efficacy.

Purpose of the Study:

• To assess the bioequivalence of Teva's sustained-release quinidine bisulphate against a reference product.
• To compare Teva's sustained-release quinidine bisulphate with short-acting quinidine sulphate.

Main Methods:

• Acute, single-dose, randomized cross-over study in seven healthy subjects.
• Pharmacokinetic parameters including Tmax, Cmax, AUC(0-inf), and fraction absorbed were measured.
• Comparison between two sustained-release formulations and a short-acting formulation.

Main Results:

• No significant bioequivalence differences were found between Teva's and Astra's sustained-release quinidine bisulphate.
• Teva's sustained-release quinidine bisulphate showed a decreased Cmax and increased Tmax compared to short-acting quinidine sulphate, but similar AUC(0-inf).
• 85% of outpatients use sustained-release quinidine bisulphate, yet only 36% receive appropriate twice-daily dosing.

Conclusions:

• Teva's sustained-release quinidine bisulphate is bioequivalent to the reference product.
• This formulation can be appropriately administered twice daily, addressing common prescribing errors.