Acute Gastrointestinal Toxic Effects of Suspensions of Unencapsulated and Encapsulated Ibuprofen in Rats

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Abstract
Purpose. The study examined the gastrointestinal (GIT) toxicity effects of suspensions of encapsulated and unencapsulated ibuprofen in male Wistar rats. Methods. Rats were randomly divided into four experimental groups and four control groups, and dosed with suspensions of encapsulated and unencapsulated ibuprofen (17 mg/kg and 44 mg/kg). Bethanechol chloride, a cholinomimetic agent (5 mg/kg), was administered 30 minutes after the dosing, to induce gastric irritation. Blood plasma concentrations were monitored in another set of rats for 12 hours using the encapsulated and unencapsulated systems, to establish drug release and exposure to the mucosa. Results. Evaluation of the upper GI segments after 7 hours revealed that the 44 mg/kg dose of the encapsulated drug significantly reduced the number of lesions present compared to the unencapsulated drug (p < 0.05). At 17 mg/kg, the encapsulated drug reduced toxicity, but not significantly compared to the unencapsulated ibuprofen. Necrosis of the mucosa was observed histopathologically in the unencapsulated drug at both doses, whereas the encapsulated drug treatment revealed preserved mucosa. The encapsulated system had a maximum plasma concentration, Cmax, and time taken to reach Cmax, (Tmax) of 26.7 µg/ml ± 1.5 and 3.6 ± 0.2 hr, respectively. The area under the plasma concentration-time curve, (AUC0–12), was 158.8 ± 23.5 µg·h/ml, confirming drug release and absorption. Conclusions. Encapsulation of ibuprofen significantly reduced gastrointestinal toxicity especially at the higher dose level and drug was released enough to subject the GI mucosa to irritation, but without the usual toxic effects.