Side Effects of Axid (nizatidine)

Axid (nizatidine) is an H2 blocker used to treat and prevent duodenal and gastric ulcers (peptic, stomach), GERD, and heartburn. 

Axid blocks the action of histamine on stomach cells and reduces their production of acid. Histamine is a naturally-occurring chemical that stimulates stomach cells to produce acid. H2-blockers inhibit the action of histamine on stomach cells, thus reducing the production of acid by the stomach. 

Since excessive stomach acid can cause or worsen stomach and duodenal ulcers, reducing stomach acid prevents ulcer formation and helps ulcers to heal.

Common side effects of Axid include

• constipation,
• diarrhea,
• fatigue,
• headache,
• insomnia,
• muscle pain,
• nausea,
• vomiting,
• dizziness,
• confusion,
• depression, and
• agitation.

Serious side effects of Axid include anemia, a reduction in white blood cells or platelets, and hepatitis.

Drug interactions of Axid include drugs that require acid for adequate absorption such as iron salts, itraconazole, ketoconazole, atazanavir, dasatinib, indinavir, and dapsone, because Axid may interfere with the absorption of these drugs. 

Conversely, Axid may increase levels of nimodipine and nisoldipine due to reduced stomach acidity. There are no adequate studies of Axid in pregnant women. 

Available evidence suggests there is little risk when Axid is used during pregnancy. 

Axid is secreted into human breast milk and may pose a potential risk to the infant. Consult your doctor before breastfeeding. 

Common side effects are:

• constipation,
• diarrhea,
• fatigue,
• headache,
• insomnia,
• muscle pain,
• nausea,
• vomiting,
• dizziness,
• confusion,
• depression, and
• agitation.

Serious but rare side effects include anemia, and a reduction in white blood cells or platelets. Hepatitis also has been reported.

Worldwide, controlled clinical trials of nizatidine included over 6,000 patients given nizatidine in studies of varying durations.

• Placebo-controlled trials in the United States and Canada included over 2,600 patients given nizatidine and over 1,700 given placebo.
• Among the adverse events in these placebo-controlled trials, anemia (0.2% vs 0%) and urticaria (0.5% vs 0.1%) were significantly more common in the nizatidine group.

Incidence in Placebo-Controlled Clinical Trials in the United States and Canada - Table 5 lists adverse events that occurred at a frequency of 1% or more among nizatidine-treated patients who participated in placebo-controlled trials.

The cited figures provide some basis for estimating the relative contribution of drug and nondrug factors to the side effect incidence rate in the population studied.

A variety of less common events were also reported; it was not possible to determine whether these were caused by nizatidine.

Hepatic - Hepatocellular injury, evidenced by elevated liver enzyme tests (SGOT [AST], SGPT [ALT], or alkaline phosphatase), occurred in some patients and was possibly or probably related to nizatidine. In some cases there was marked elevation of SGOT, SGPT enzymes (greater than 500 IU/L) and, in a single instance, SGPT was greater than 2,000 IU/L.

The overall rate of occurrences of elevated liver enzymes and elevations to 3 times the upper limit of normal, however, did not significantly differ from the rate of liver enzyme abnormalities in placebo-treated patients. All abnormalities were reversible after discontinuation of Axid (nizatidine).

Since market introduction, hepatitis and jaundice have been reported. Rare cases of cholestatic or mixed hepatocellular and cholestatic injury with jaundice have been reported with reversal of the abnormalities after discontinuation of Axid (nizatidine) .

Cardiovascular- In clinical pharmacology studies, short episodes of asymptomatic ventricular tachycardia occurred in 2 individuals administered Axid (nizatidine) and in 3 untreated subjects.

CNS - Rare cases of reversible mental confusion have been reported.

Endocrine - Clinical pharmacology studies and controlled clinical trials showed no evidence of antiandrogenic activity due to Axid (nizatidine) . Impotence and decreased libido were reported with similar frequency by patients who received Axid (nizatidine) and by those given placebo. Rare reports of gynecomastia occurred.

Hematologic - Anemia was reported significantly more frequently in nizatidine- than in placebo-treated patients. Fatal thrombocytopenia was reported in a patient who was treated with Axid (nizatidine) and another H₂-receptor antagonist. On previous occasions, this patient had experienced thrombocytopenia while taking other drugs. Rare cases of thrombocytopenic purpura have been reported.

Integumental - Sweating and urticaria were reported significantly more frequently in nizatidine- than in placebo-treated patients. Rash and exfoliative dermatitis were also reported. Vasculitis has been reported rarely.

Hypersensitivity - As with other H₂-receptor antagonists, rare cases of anaphylaxis following administration of nizatidine have been reported. Rare episodes of hypersensitivity reactions (eg, bronchospasm, laryngeal edema, rash, and eosinophilia) have been reported.

Body as a Whole - Serum sickness-like reactions have occurred rarely in conjunction with nizatidine use.

Genitourinary - Reports of impotence have occurred.

Other - Hyperuricemia unassociated with gout or nephrolithiasis was reported. Eosinophilia, fever, and nausea related to nizatidine administration have been reported.

No interactions have been observed between Axid (nizatidine) and theophylline, chlordiazepoxide, lorazepam, lidocaine, phenytoin, and warfarin.

Axid (nizatidine) does not inhibit the cytochrome P-450-linked drug-metabolizing enzyme system; therefore, drug interactions mediated by inhibition of hepatic metabolism are not expected to occur.

In patients given very high doses (3,900 mg) of aspirin daily, increases in serum salicylate levels were seen when nizatidine, 150 mg b.i.d., was administered concurrently.