DESCRIPTION

Nizatidine USP is a histamine H2 -receptor antagonist. Chemically, it is N-[2-[[[2-[(dimethylamino)methyl]-4- thiazolyl] methyl]thio]ethyl]-N'-methyl-2-nitro-1,1-ethenediamine.

The structural formula is as follows:

Structure

Nizatidine has the molecular formula C12H21N5O2S2 representing a molecular weight of 331.46. It is an off-white to buff crystalline powder that is soluble in water. Nizatidine has a bitter taste and mild sulfur-like odor. Each capsule, for oral administration, contains 150 mg or 300 mg of nizatidine. In addition each capsule contains the following inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, lactose monohydrate, stearic acid, and talc. Each capsule shell contains gelatin, titanium dioxide and yellow iron oxide. The 300 mg capsule shell also contains black iron oxide and red iron oxide. The capsule imprinting ink contains ammonium hydroxide, black iron oxide, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, potassium hydroxide, propylene glycol and shellac.

CLINICAL PHARMACOLOGY

Nizatidine is a competitive, reversible inhibitor of histamine at the histamine H2-receptors, particularly those in the gastric parietal cells.

Antisecretory Activity

1.Effects on Acid Secretion

Nizatidine significantly inhibited nocturnal gastric acid secretion for up to 12 hours. Nizatidine also significantly inhibited gastric acid secretion stimulated by food, caffeine, betazole, and pentagastrin (Table 1).

Table 1
Effect of Oral Nizatidine on Gastric Acid Secretion
	Time After Dose (h)	% Inhibition of Gastric Acid Output by Dose (mg)
		20-50	75	100	150	300
Nocturnal	Up to 10	57		73