Muscarinic Pharmacology: No Need to Memorize

The following is a summary of a one hour lecture on muscarinic receptor agonists provided to pharmacy students in their second semester of professional study. During the previous semester students complete prerequisite courses in physiology and biochemistry. The lecture is preceded by lectures covering pharmacokinetics, pharmacodynamics, receptor theory, and the autonomic nervous system (ANS). The lecture represents the students' first exposure to a pharmacologic class of agents. In conjunction with the pharmacology course, students are enrolled in a medicinal chemistry course. The objectives of the lecture are to present the pharmacology of direct muscarinic receptor agonists, and to assist the students develop an approach to the application of prerequisite knowledge to the study of pharmacology. Muscarinic pharmacology is frequently one of the first topics covered in entry-level pharmacology courses. As a result, it is important that students apply prerequisite knowledge (e.g., physiology, biochemistry, pharmacodynamics, and receptor theory) to the comprehension of pharmacology. If students attempt to understand pharmacology, the quantity of memorization decreases. Although muscarinic agonists are generally not found among lists of the "Top 200" prescription medications they serve as a useful model class. Prior to the lecture students are provided a few scenarios and exercises to prepare them for the study of muscarinic pharmacology (Appendix). The pharmacology of muscarinic agonists is presented using an organ system approach. The major target organs of muscarinic agonists include: blood vessels, heart, eyes, lungs, and gastrointestinal and urinary smooth muscle(1). For each organ system the effect of stimulation of muscarinic receptors is presented with emphasis on correlation to the activities of the parasympathetic nervous system. Based upon the effect on organ function, potential therapeutic uses and adverse effects are discussed. Examples of agents are provided and distinguishing features presented. It is hoped that at the conclusion of the lecture students will be able to apply knowledge of the ANS to muscarinic pharmacology and the only information requiring memorization is the names of the pharmacologic agents.