How does physostigmine reverse TCA toxicity?
The main action of TCAs is to inhibit neuronal uptake and prolong the action of NE in the neuroeffector junction. TCAs also have significant muscarinic and alpha-receptor blocking activity (see page 92). A common side effect of their use is a dry mouth (muscarinic block). At high doses such as overdose/suicide a major problem is muscarinic receptor blockade both in the periphery and CNS. Physostigmine crosses the BBB and can reverse actions at both sites.
