title: A comparison of withdrawal in rats implanted with different types of morphine pellets.
abstract: Time course and duration and physical dependence was investigated in rats implanted subcutaneously with 3 different types of morphine (M) pellets. Each was formulated according to the method of Gibson and Tingstand [8], but differed in surface area and hardness. Animals were maintained for 19 days after implantation and physical dependence was assessed every other day. Severity of naloxone (Nx)-induced withdrawal was quantified by the use of a composite symptom score and weight loss. Withdrawal severity was greatest following implantation of a pellet (Type C) of large surface area and low hardness rating, and least following implantation of a pellet (Type A) of small surface area and high hardness rating. Abstinence severity which resulted from implantation of a pellet (Type B) of moderate surface area and low hardness rating was intermediate. When 2 pellets were implanted the difference between Type C and B was amplified. It was concluded that formulation per se was not sufficient for specifying M pellet characteristics.
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004343:Drug Implants; D006244:Hardness; D006801:Humans; D008297:Male; D009020:Morphine / Q000008:administration & dosage* / Q000494:pharmacology; D009021:Morphine Dependence / Q000150:complications / Q000503:physiopathology; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D013375:Substance Withdrawal Syndrome / Q000139:chemically induced / Q000209:etiology / Q000503:physiopathology*; D013499:Surface Properties; D013607:Tablets; D013997:Time Factors
chemical_list: D004343:Drug Implants; D013607:Tablets; D009270:Naloxone; D009020:Morphine