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PHARMACOLOGICAL ACTIVITIES - TOXICOLOGY - DRUG INTERACTIONS

Picrorhiza kurroa (Picrorhiza)

Rhizoma Picrorhizae is a distinguished medicinal herb of the Ayurvedic medicinal system, used
mainly for the treatment of a variety of liver ailments. The major biologically active constituents
are iridoid glycosides, cucurbitacin triterpenes and simple phenols (WHO, 2009). The iridoid
glycoside mixture kutkin (picroside and kutkoside) isolated from Rhizoma Picrorhizae has
shown significant hepato-protective efficacy in animal models of galactosamine, paracetamol,
thioacetamide and carbon tetrachloride induced hepatic damage. It has also exhibited anti-viral
and immune-stimulant activities (Verma et al., 2009). The mechanism of action of Rhizoma
Picrorhizae extract in liver protection involves kutkin, which can increase the activity rates
of nucleolar polymerase A, leading to increased protein synthesis and subsequent enhanced
regenerative ability. Kutkins scavenge free radicals and guard hepatocytes from the damage
caused by lipid peroxidation through antioxidant activity. Apocynin, another active constituent
of Rhizoma Picrorhizae, is a strong nicotinamide adenine dinucleotide phosphate-oxidase
inhibitor and has shown anti-inflammatory properties. The mechanism of action of kutkins
appears to be the same as that of silymarin, a hepato-protective constituent of Silybum
marianum (Vaidya et al., 1996).

Toxicity for Rhizoma Picrorhizae has not been documented in dogs and cats when administered orally in
therapeutic doses. In mice, the LD for aqueous ethanol extract of Rhizoma Picrorhizae is 1.09 g/kg of body
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TOXICOLOGY Rhizoma Picrorhizae in mice is >2 g/kg of body weight intragastrically (Lee, 1982). In rats, the LD of kutkin,
weight intraperitoneal, indicating low toxicity (Dhar et al., 1973). The LD for 70% methanol extract of
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an active constituent of Rhizoma Picrorhizae, is >2,600 mg/kg of body weight (CSIR, 1989-1990).

Equivalent toxic dose in 20 kg dog: 21.8 g IP of Rhizoma Picrorhizae ethanol extract.
Equivalent toxic dose in 5 kg cat: 5.45 g IP of Rhizoma Picrorhizae ethanol extract.

DRUG Validated interactions studies do not exist for Rhizoma Picrorhizae preparations. Clinical
INTERACTIONS interactions with other drugs have not been reported.

Hepato -VM TM | 7