e. How Supplied. Diphenhydramine hydrochloride is supplied as a powder, as
25-mg and 50-mg capsules, as an elixir, as an ingredient in an expectorant cough
syrup (Benylin Expectorant), and as a solution for intravenous or intramuscular
injection. The injection is supplied in 10-ml vials (10-mg per ml or 50-mg per ml) and in
1-ml ampules (50 mg each).
Dimenhydrinate (Dramamine) is a mixture of diphenhydramine (discussed
above) and 8-chlorotheophylline. The latter contributes very little to the effectiveness
of the mixture as an antihistamine or antiemetic. The chief use of dimenhydrinate is as
an antinauseant in motion sickness. The usual dose is 50-mg, 4 times daily. It is
supplied as 50-mg tablets.
4-30. MECLIZINE HYDROCHLORIDE
a. Action and Uses. Meclizine (Bonine, Antivert) is used to prevent or treat
motion sickness, vertigo, labyrinthitis, and radiation sickness. It is long-acting (9 to 24
b. Administration. The usual adult dose is 25-mg daily.
c. Contraindications. Because of the sedative effects of this drug, it should
not be used when alertness is required. It is contraindicated in pregnancy.
d. How Supplied. Meclizine is supplied in 12.5-mg and 25 mg tablets and as
25-mg chewable tablets.
4-31. PROMETHAZINE HYDROCHLORIDE
a. Uses. Promethazine (Phenergan) is a very potent phenothiazine-type
antihistamine with a long duration of action. In addition to its uses as an antihistamine
for allergic condition, it is also useful as an antitussive, an antiemetic, and an
obstetrical, surgical, or nighttime sedative.
b. Administration. The usual oral or parenteral dose is 25-mg, repeated after
4 hours, if necessary.
c. How Supplied. Promethazine hydrochloride is supplied as an injection (25-
mg per ml), 25-mg tablets, and 25-mg suppositories. It is also an ingredient in an
expectorant cough syrup (Phenergan Expectorant).