Ritonavir, a
protease inhibitor drug, is commonly used in
AIDS therapy. As with other chemotherapeutic drugs that cause gastrointestinal adverse effects,
ritonavir treatment is associated with significant
nausea and
vomiting. This study investigated whether Scutellaria baicalensis, and its active
flavonoid constituent,
baicalein, attenuate the gastrointestinal effects of
ritonavir. The effects of herb administration were evaluated in
ritonavir-treated rats using a rat
pica model, which simulates
nausea and
vomiting in humans. The effects of herb administration on gastric emptying in rats were also measured.
Ritonavir treatment resulted in increased
kaolin intake or severe
pica, the intensity of which was reduced significantly with S. baicalensis administration (1 mg kg(-1); P<0.05). High-performance liquid chromatography analysis of S. baicalensis showed the presence of an extremely potent
flavonoid constituent,
baicalein. The study aimed to determine if
baicalein contributed to the anti-
pica effect of the extract. It was observed that
baicalein dose-dependently decreased
pica in
ritonavir-treated rats (P<0.001). In addition to inducing
pica,
ritonavir also significantly delayed gastric emptying, which could contribute to
ritonavir-induced gastrointestinal dysfunction. When S. baicalensis extract was administered to
ritonavir-treated rats the delayed gastric emptying was significantly attenuated (P<0.05). The results suggest that S. baicalensis and the constituent
baicalein reduce the gastrointestinal dysfunction caused by
ritonavir. It is concluded that S. baicalensis may potentially have a role to play in reducing drug-induced adverse effects.