Analgesic activity and safety of ash of silver used in Indian system of medicine in mice: A reverse pharmacological study

OBJECTIVE: To study the analgesic activity of ash of silver used in Indian system of medicine and to explore its safety. MATERIALS AND METHODS: Albino mice of either sex (20-30 gm) were used to investigate the role of ash of silver against noxious stimuli: thermal (Eddy's hot plate and analgesiometer), mechanical (tail clip), and chemical (0.6% acetic acid induced writhing). An effort was made to find nature and site of action of ash of silver following naloxone pre-treatment. Maximum tolerated dose (MTD) and lethal dosage 50 (LD50) were also studied along with toxicological aspects of ash of silver. RESULTS: Test drug (ash of silver) at a dose of 50 mg/kg p.o exhibited analgesic activity against thermal, mechanical, and chemical stimuli. Analgesic effects were compared with the standard drug, morphine, in thermal and mechanical noxious stimuli and to aspirin in chemical stimulus. Analgesic activity of the test drug was reduced following naloxone pre-treatment. MTD was found out to be greater than 1.5 g/kg p.o. LD50 was 2 g/kg p.o. Fraction of mice showed symptoms of argyria as explained by autopsy reports. CONCLUSION: Test drug exhibited moderate analgesic activity at 50 mg/kg p.o against all type of noxious stimuli, also suggesting a role of opioidergic system. The ash of silver was been found to be safe upto a dose of 1.5 g/kg p.o. in mice without any untoward toxicity. Further studies are required to explore the effect of ash of silver on pain mediators and excitatory neurotransmitters like glutamate, aspartate, or N-methyl-D-aspartic acid (NMDA).