<p>Evaluation of the antidiarrheal activity of the leaf extract of <em>Parquetina nigrescens</em> and formulation into oral suspensions</p>

Abstract

Purpose Parquetina nigrescens (Pn) extract was evaluated for safety and antidiarrheal activity, formulated into stable suspensions, and characterized. Methods Acute toxicity of the extract based on Organization for Economic Cooperation and Development-423 guidelines was performed. The antidiarrheal effects of the extract on castor oil-induced diarrhea in four groups of Wistar rats were determined. The first and second groups received 5 and 200 mg/kg body weight (bw) of the extract, while the third and fourth groups received normal saline (5 mg/kg bw) and loperamide (5 mg/kg bw) as negative and positive controls, respectively. Pn extract was used at 1.25% w/v to formulate structured vehicle (carboxylmethylcellulose, polyvinylpyrrolidone and tragacanth) suspensions. The suspensions were tested for pharmacological activity and characterized. Results Acute toxicity gave a lethal dose 50 (LD50) that is greater than 300 and less than 2,000 mg/kg bw. A reduction in intestinal transit by 0.14 and 0.15% at 5 and 200 mg/kg of the extract was achieved as compared to an inhibition of 0.12% by 5 mg/kg loperamide. There was a dose-dependent decrease in the frequency of watery stool passed in castor oil-induced rats by 35.29% and 64.70% at 5 and 200 mg/kg, respectively. All the suspensions inhibited diarrhea, exhibiting a dose-dependent pattern and remained stable after 4 weeks. Their pH values ranged from 4.60±2.73 to 4.73±1.91, while viscosity ranged from 3.50±1.23 to 6.75±1.24 Pas at 60 rpm. Conclusion The results suggest that Pn possesses significant antidiarrheal activity. Suspensions of Pn were successfully formulated in structured vehicles and were effective in the control of diarrhea in Wistar rats.

Underlying Mechanisms of Anti-spasmodic, Antidiarrheal, Antioxidant and Acute Toxicity Assessments of Aqueous Extract of Mentha Suaveolens Ehrh and its Fourier Transform Infra-red Spectroscopy Analysis

“…Furthermore, AEMS delayed the gastrointestinal transit in rats compared to the control which suggest the increase the absorption of water and electrolyte from the gastrointestinal tract as a probable mechanism of its antidiarrheal effect. These results were comparable to those observed in the control groups treating with loperamide, which is one of the most efficient and widely used antidiarrheal drugs [30,31,32], at the concentrations of 5mg/kg and 10mg/kg. Loperamide was described to regulate the gastrointestinal tract, to reduce transit in the intestine, and to decrease colon flow rate [33].…”

“A Review of Parquetina nigrescens (Afzel.) Bullock, A Plant for Traditional Medicine: Phytochemical and Pharmacological Properties”

“…The antidiarrheal effects of the suspension at doses of 5 mg/kg and 200 mg/kg were also dose-dependent and lasted for 4 weeks. Both the extract and the suspension had substantial antidiarrheal activity [ 63 ]. Varying doses of both extract and suspension within the range of 5 mg/kg to 200 mg/kg body weight should be tested to help develop optimized doses for consideration in the treatment of diarrhoea.…”