Usage
Nizatidine is prescribed for the treatment and maintenance of duodenal ulcers, benign gastric ulcers, and gastroesophageal reflux disease (GERD), including erosive esophagitis and associated heartburn. It’s also used to manage gastric or duodenal ulcers associated with non-steroidal anti-inflammatory drug (NSAID) use.
It is pharmacologically classified as a histamine H2-receptor antagonist.
Nizatidine works by competitively inhibiting the action of histamine at the H2 receptors of the parietal cells in the stomach, thereby reducing gastric acid secretion.
Alternate Names
Nizatidine is also known by various brand names, including Axid, Nizac, and Tacidine.
How It Works
Pharmacodynamics: Nizatidine binds competitively to H2 receptors on the basolateral membrane of parietal cells in the stomach. This blocks histamine’s stimulation of these receptors, leading to a reduction in both basal and stimulated gastric acid secretion (including that stimulated by food, caffeine, insulin, and pentagastrin). This reduces the total volume of gastric juice and hydrogen ion concentration. It doesn’t affect pepsin activity, though total output is reduced due to a lower volume of gastric secretions. Nizatidine does not affect serum gastrin levels.
Pharmacokinetics: Nizatidine is well absorbed after oral administration, with peak plasma concentrations reached within 1-3 hours. Food may slightly delay absorption but does not significantly affect the overall extent. It has limited metabolism in the liver (about 35%), with a systemic bioavailability of approximately 70%. Nizatidine is primarily excreted unchanged by the kidneys, with a half-life of 1-2 hours. The elimination half-life increases with reduced renal function.
Mode of Action: Nizatidine acts by competitive inhibition of histamine at H2 receptors on parietal cells.
Elimination pathways: Predominantly renal excretion.
Dosage
Standard Dosage
Adults:
- Duodenal Ulcer (Active): 300 mg once daily at bedtime or 150 mg twice daily. Treatment typically lasts 4-8 weeks.
- Duodenal Ulcer (Maintenance): 150 mg once daily at bedtime for up to 12 months.
- Gastric Ulcer (Benign): 300 mg once daily at bedtime or 150 mg twice daily for up to 8 weeks.
- GERD: 150 mg twice daily or 300 mg once daily at bedtime for up to 12 weeks.
Children:
Limited information is available on pediatric dosing for Nizatidine. Some studies suggest dosages ranging from 10-20 mg/kg/day for infants over one month old, adolescents and older children, up to a maximum of 300 mg/day, but the safety and efficacy in pediatric populations are not fully established.
Special Cases:
- Elderly Patients: No specific dose adjustment is typically required, but caution is advised, especially in the presence of renal impairment.
- Patients with Renal Impairment:
- CrCl 20-50 mL/min: 150 mg daily.
- CrCl <20 mL/min: 150 mg every other day for active ulcers, GERD, and benign gastric ulcers or every 3 days for duodenal ulcer maintenance.
- Patients with Hepatic Dysfunction: No specific dose adjustment for uncomplicated liver disease; not recommended in hepatic failure.
- Patients with Comorbid Conditions: Exercise caution and consider dose adjustments based on renal function and other comorbidities.
Clinical Use Cases
No standard dosage recommendations exist for intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations with nizatidine. For surgical procedures, a dose of 300 mg the night before or morning of surgery has been studied.
Dosage Adjustments
Dose adjustments are primarily based on creatinine clearance (CrCl) in patients with renal impairment. Consider modifications based on hepatic dysfunction or drug interactions.
Side Effects
Common Side Effects:
Constipation, diarrhea, nausea, headache, somnolence.
Rare but Serious Side Effects:
Hepatitis, thrombocytopenia, agranulocytosis, hypersensitivity reactions (including anaphylaxis), confusion.
Long-Term Effects:
Vitamin B12 deficiency (with prolonged use).
Adverse Drug Reactions (ADR):
Stevens-Johnson syndrome, toxic epidermal necrolysis (rare).
Contraindications
Hypersensitivity to nizatidine or other H2-receptor antagonists.
Drug Interactions
Nizatidine can affect the absorption of certain medications, such as ketoconazole, itraconazole, and delavirdine, due to its effect on gastric pH. It can also potentially interact with drugs metabolized by the CYP450 system, although the interactions are generally less significant than with cimetidine. It may decrease the effects of drugs that require an acidic environment for absorption, like mycophenolate, nelfinavir, nilotinib, mesalamine and neratinib. Conversely, it can increase the levels of pexidartinib and midazolam.
Pregnancy and Breastfeeding
Nizatidine is categorized as Pregnancy Category B. While animal studies haven’t shown fetal harm, there are limited human data. Its use during pregnancy should be considered only if clearly needed. Nizatidine is excreted in breast milk, so caution is advised when administered to nursing mothers.
Drug Profile Summary
- Mechanism of Action: Competitive inhibition of histamine at H2 receptors, reducing gastric acid secretion.
- Side Effects: Constipation, diarrhea, nausea, headache. Rarely, hepatitis or blood dyscrasias.
- Contraindications: Hypersensitivity to nizatidine or other H2 receptor antagonists.
- Drug Interactions: Affects absorption of certain drugs and may interact with those metabolized by CYP450.
- Pregnancy & Breastfeeding: Category B; use with caution.
- Dosage: Refer to detailed dosage guidelines above.
- Monitoring Parameters: Renal function tests in patients with renal impairment, liver function tests with long-term use.
Popular Combinations
Nizatidine is sometimes combined with antacids for symptomatic relief of heartburn or dyspepsia.
Precautions
Screen for allergies and assess renal and hepatic function before initiating therapy. Exercise caution in pregnancy and breastfeeding.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Nizatidine?
A: The dosage depends on the indication: 300 mg at bedtime or 150 mg twice daily for active duodenal or benign gastric ulcer; 150 mg at bedtime for duodenal ulcer maintenance; and 150 mg twice daily for GERD. Dose adjustments are needed for renal impairment.
Q2: How does nizatidine differ from other H2 blockers?
A: Nizatidine has a lower potential for drug interactions compared to cimetidine.
Q3: Can nizatidine be used in patients with liver disease?
A: It can be used in patients with uncomplicated hepatic dysfunction but is not recommended in patients with liver failure.
Q4: What are the common side effects of nizatidine?
A: Common side effects include constipation, diarrhea, nausea, and headache.
Q5: Is nizatidine safe during pregnancy?
A: It’s Pregnancy Category B, meaning animal studies show no harm, but human data are limited. Use only if clearly needed.
Q6: How long can a patient take nizatidine?
A: For active ulcers, treatment is usually 4-8 weeks. Maintenance therapy for duodenal ulcer can continue for up to 12 months. GERD treatment can last up to 12 weeks.
Q7: Does nizatidine interact with alcohol?
A: No significant interaction has been reported.
Q8: Can nizatidine be crushed or chewed?
A: Tablets can be swallowed whole or dissolved in water.
Q9: What should be done in case of an overdose?
A: Supportive care and symptomatic treatment should be provided. Consider gastric lavage or activated charcoal.
Q10: Are there any specific dietary restrictions while taking nizatidine?
A: No specific dietary restrictions are generally required.
