Muscarinic Antagonists Attropa be -Atropine and Scopolamine are belladona alkaloids (competitive inhibitors) -Drugs differ in their CNS effects,scopolamine permeates the blood-brain barrier -At therapeutic doses atropine has negligible effects upon the CNS, scopolamine even at low doses has prominent CNS effects. Mechanism of drug action Competitively block muscarinic receptors Salivary,bronchial,and sweat glands are most sensitive to atropine Smooth muscle and heart are intermediate in responsiveness In the eye,causes pupil dilation and difficulty for near vision accommodation Relaxation of the Gl,slows peristalsis 88 Muscarinic Antagonists Attropa belladona - Atropine and Scopolamine are belladona alkaloids (competitive inhibitors) - Drugs differ in their CNS effects, scopolamine permeates the blood-brain barrier - At therapeutic doses atropine has negligible effects upon the CNS, scopolamine even at low doses has prominent CNS effects. Mechanism of drug action - Competitively block muscarinic receptors - Salivary, bronchial, and sweat glands are most sensitive to atropine - Smooth muscle and heart are intermediate in responsiveness - In the eye, causes pupil dilation and difficulty for near vision accommodation - Relaxation of the GI, slows peristalsis