Prevention of development of tolerance and dependence to opiate in mice by BR-16A (Mentat), a herbal psychotropic preparation.

Chronic treatment with BR-16A (20-500 mg/kg) followed by saline on days 1 to 9 failed to produce any significant change in tail-flick latency from the saline-pretreated group in mice. Repeated administration of BR-16A(20-500 mg/kg) for 9 days however, attenuated the development of tolerance to the analgesic effect of morphine (10 mg/kg). BR-16A (20-500 mg/kg) also suppressed, in a dose-dependent manner, the development of morphine dependence as assessed by naloxone (2 mg/kg)-precipitated withdrawal on day 10 of testing.