Comparative Studies on Intramuscular and Oral Effective Doses of Some Anticholinergic Drugs

Sixteen healthy volunteers received propantheline, methylscopolamine or butylscopolamine in oral as well as i.m. administration. After propantheline and methylscopolamine salivary secretion was found to be more influenced than the heart rate and the near point of accommodation. The relations between i.m. and oral doses producing comparable total effects on salivation were 1: 10 for propantheline and 1: 100 for methylscopolamine. After oral butylscopolamine in doses up to 480 mg no anticholinergic effects were observed. In contrast to the other compounds, i.m. butylscopolamine produced only transient effects and influenced mainly the near point of accommodation. It is concluded that presumably less than 10 per cent of methylscopolamine and probably only very little of butylscopolamine is absorbed in the gastrointestinal tract.