ORIGANS

Lidocaine, like other local anaesthetics, causes a reversible blockade of impulse propagation along nerve fibres by preventing the inward movement of sodium ions through the nerve membrane. Local anaesthetics of the amide-type are thought to act within the sodium channels of the nerve membrane.

Mepyramine is a first generation antihistamine, targeting the H1 receptor. However, it rapidly permeates the brain and so often causes drowsiness as a side effect. Mepyramine is a histamine H1 receptor inverse agonist. It binds to a G protein-coupled form of the receptor and promotes a G protein-coupled inactive state of the H1 receptor that interferes with the Gq/11-mediated signaling. Mepyramine competes with histamine for binding at H1-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare, and pruritus. The sedative properties of mepyramine occur at the subcortical level of the CNS. It has mild hypnotic properties and some local anesthetic action and is used for allergies (including skin eruptions) both parenterally and locally. It is a common ingredient of cold remedies.

Zinc blocks the intestinal absorption of copper from the diet and the reabsorption of endogenously secreted copper. Zinc induces the production of metallothionein in the enterocyte, a protein that binds copper thereby preventing its transfer into the blood. The bound copper is then eliminated in the stool following desquamation of the intestinal cells.