Bioequivalency of doxycycline products

Area of Science:

• Pharmacokinetics and Drug Bioavailability
• Pharmaceutical Sciences
• Clinical Pharmacology

Background:

• Doxycycline is a widely used antibiotic with various available dosage forms.
• Ensuring bioequivalence between different doxycycline products is crucial for therapeutic efficacy.
• Variations in formulation and brand may impact drug absorption and bioavailability.

Purpose of the Study:

• To evaluate and compare the bioavailability of three different brands and three dosage forms of doxycycline.
• To determine the bioequivalence of generic doxycycline capsule products against the innovator's product.
• To assess the impact of different dosage forms (capsule, oral solution, oral suspension) on doxycycline absorption.

Main Methods:

• A crossover study design involving six healthy subjects.
• Administration of single oral doses equivalent to 200 mg of doxycycline.
• Comparison of innovator's oral solution, innovator's capsules, two non-innovator capsules, and innovator's oral suspension.
• Serum drug levels measured over 48 hours and cumulative urinary excretion over 120 hours.
• In vitro dissolution testing of capsule products.

Main Results:

• No statistically significant differences in bioequivalence indicators were found among the three capsule products.
• The capsule products were deemed bioequivalent to each other and to the oral solution.
• Statistically significant differences in the rate of absorption were observed between capsule products and the oral suspension.
• In vitro dissolution rates correlated with in vivo absorption rates for capsule formulations.

Conclusions:

• Generic doxycycline capsule formulations are bioequivalent to the innovator's product and oral solution.
• The oral suspension formulation of doxycycline exhibits different absorption characteristics compared to capsules.
• In vitro dissolution testing can serve as a predictor of in vivo absorption performance for doxycycline capsules.