Pharmacological studies of mabuterol, a new selective beta 2-stimulant. III: Effects on the central nervous system, striated muscle and carbohydrate and lipid metabolism

Abstract

Effects of dl-1-(4-amino-3-chloro-5-trifluoromethyl-phenyl)-2-tert.-butylamino-etha nol hydrochloride (mabuterol) on the central nervous system, the striated muscle and the carbohydrate and lipid metabolism were investigated in comparison with those of isoprenaline and salbutamol. Mabuterol caused the following changes in behavior: increased touch response (10 mg/kg p.o.), decreased spontaneous movement and ptosis (30 and 100 mg/kg p.o., resp.), observed for 240-300 min. Mabuterol (5 mg/kg p.o. and 2.5 mg/kg s.c.) prolonged the sleeping time induced by hexobarbital Na, but not dose-dependently. Mabuterol depressed reactive movement at 80 mg/kg p.o. and 40 mg/kg s.c. in the rotarod test, at 160 mg/kg p.o. and 40 mg/kg s.c. in the traction test and at 200 mg/kg p.o. and 160 mg/kg s.c. in the inclined plane test in mice, whereas isoprenaline and salbutamol were almost ineffective. Analgesic activity of mabuterol was found in the acetic acid writhing test but not in the bradykinin-induced nociception test. An anticonvulsive effect was not observed. Mabuterol (10 mg/kg i.v.) produced a change in the spontaneous EEG of one of three rabbits, showing synchronization of cortical activity with sedation. Equipotent dose (i.v.) ratios of mabuterol to isoprenaline were 10.2, 30 and 133 in the depression of incomplete tetanic contraction of cat soleus muscle, hypotensive effect and tachycardia respectively, whereas neither indirect nor direct electrical stimulation induced contraction of diaphragm and gastrocnemius muscle was affected. Equipotent dose (s.c.) ratios of mabuterol to isoprenaline were 2.07, 4.64 and 3.21 in increasing plasma levels of glucose, lactic acid and free fatty acids respectively. Mabuterol caused no remarkable change in myocardial glycogen content.