Dimenhydrinate Sunward Mechanism of Action

Pharmacology: Dimenhydrinate is diphenhydramine theoclate and has the general properties of diphenhydramine hydrochloride. It is basically an antihistamine with anticholinergic and sedative side effects. It appears to compete with histamine for cell receptor sites on effector cells.
It is readily absorbed from the gastrointestinal tract. Following oral administration, the effects start within 15 to 30 minutes. It rapidly leaves the circulation and reaches a peak concentration in tissues in about 1 hour. The duration of action of a single dose is approximately 3 to 6 hours. The tissues are almost free of the drug in about 6 hours.
The highest concentration occurs in the lung, with progressively lower concentrations in the spleen, kidney, brain, muscle and skin. Little, if any, of the drug is excreted unchanged in the urine, most appears as degradation products that are almost completely excreted within 24 hours. The main site of metabolic transformation is the liver, but the lung and kidney can also metabolise the compound.