Metoclopramide is the most commonly-employed anti-emetic used with end of life drugs. Common brand names include Maxalon and Pramin. This drug performs two useful actions: a) it prevents nausea and vomiting by blocking dopamine, and b) it increases the absorbtion of the lethal drug by facilitating gastric emptying. The usual regime is to take 3 x 10mg tablets (30mg) about an hour before the planned ingestion of the lethal drug.
An alternative form of administration is to take the drug for 48 continuous hours prior to the planned death at the usual 1 tablet (10mg) every 8 hours (ie x3 per day). Note - this regime removes the need to synchronise the taking of the metoclopramide with the taking of the lethal drug. It also serves to uncover any possible adverse effects of the drug leaving time enough to seek an alternative, if necessary.
Note - The dopamine-blocking action can lead to significant side effects in some individuals, including neurological movement disorders (extrapyramidal symptoms), eg. spasm, jerks, rigidity, and tremor etc which may make this drug unusable.
Note - Although the drug is usually prescription-controlled, it is also available over the counter some countries such as in Mexico. Some online distributors of Nembutal provide metoclopramide tablets as an added extra with each purchase.