Interaction study between cephalexin and omeprazole after oral administration in dogs

Cephalexin, a widely used first-generation cephalosporin antibiotic, is frequently prescribed in veterinary medicine for various bacterial infections in canines. Concurrently, omeprazole, a proton pump inhibitor (PPI), is commonly used to manage gastric ulcers and related conditions. Understanding potential drug interactions is crucial for optimizing therapeutic outcomes. We conducted a study to assess the impact of omeprazole on the disposition of cephalexin in canines. Ten healthy mixed-breed dogs received cephalexin alone and after a 5-day pretreatment with omeprazole. Pharmacokinetic parameters were evaluated using high-pressure liquid chromatography (HPLC) analysis. The mean plasma concentration-time curves showed a relatively slow absorption phase with comparable peak plasma concentrations (Cmax) of 17.32±4.21 μg/mL for cephalexin alone and 16.66±5.26 μg/mL when administered with omeprazole. Similarly, other pharmacokinetic parameters, including area under the plasma concentration-time curve (AUC), elimination half-life (T1/2), absorption half-life (T1/2a), and total body clearance (Cl/F), did not exhibit significant differences between treatments. Our results demonstrate that omeprazole did not significantly alter the pharmacokinetics of cephalexin in canines, allowing for their effective combination without the need for dosage adjustments.