NIZATIDINE
Clinical safety rating: safe
Animal studies have demonstrated safety
H2-receptor antagonist that competitively inhibits histamine at H2 receptors on parietal cells, reducing gastric acid secretion.
| Metabolism | Metabolized in the liver via CYP450 isoenzymes (CYP1A2, CYP3A4) and non-CYP pathways; forms N-monodesmethylnitzatidine as a minor metabolite. |
| Excretion | Primarily renal (urine) via tubular secretion and glomerular filtration: approximately 60-65% of the dose is excreted unchanged in urine. Biliary/fecal excretion accounts for <10% of the dose, with the remainder as metabolites (N2-monodesmethylnizatidine and nizatidine sulfoxide). |
| Half-life | Terminal elimination half-life in healthy adults is 1.0-1.7 hours (mean ~1.5 h). In patients with renal impairment (CrCl <20 mL/min), half-life is prolonged to 3.5-11 hours, necessitating dose adjustment. In elderly patients, half-life may increase slightly due to age-related decline in renal function. |
| Protein binding | Approximately 35% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is 0.8-1.5 L/kg (mean ~1.2 L/kg), indicating distribution into total body water. This suggests extensive tissue penetration, including into gastric mucosa and cerebrospinal fluid (CSF). |
| Bioavailability | Oral bioavailability is approximately 70% (range 60-80%). Administration with food may slightly delay absorption but does not significantly affect total absorption. Bioavailability is essentially complete via intravenous route. |
| Onset of Action | Oral: Inhibition of gastric acid secretion begins within 0.5-1 hour post-dose. Peak effect occurs at 1-3 hours. IV: Onset is within minutes; maximal acid suppression by 0.5-1 hour. |
| Duration of Action | Duration of acid suppression (elevation of gastric pH >3.5) persists for 8-10 hours after a single oral dose, allowing twice-daily dosing. A single 300 mg oral dose at bedtime suppresses nocturnal acid secretion for up to 12 hours. |
150 mg orally twice daily or 300 mg orally once daily at bedtime.
| Dosage form | CAPSULE |
| Renal impairment | CrCl 20-50 mL/min: 150 mg orally once daily. CrCl <20 mL/min: 150 mg orally every other day. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C). |
| Pediatric use | For gastroesophageal reflux: 6-10 mg/kg/day orally divided twice daily, max 300 mg/day. For peptic ulcer: not recommended. |
| Geriatric use | No specific dose adjustment except based on renal function; consider lower initial doses due to potential age-related renal decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions May cause confusion more commonly in elderly or severely ill patients.
| Breastfeeding | Minimal excretion into breast milk; M/P ratio unknown. Considered compatible with breastfeeding due to low oral bioavailability in infants. |
| Teratogenic Risk | FDA Pregnancy Category B. Animal studies have not shown fetal harm. No adequate human studies in pregnant women; however, risk appears low across all trimesters. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Common Effects | GERD |
| Serious Effects |
["Known hypersensitivity to nizatidine or other H2-receptor antagonists"]
| Precautions | ["Symptomatic response to therapy does not preclude presence of gastric malignancy","Use with caution in patients with moderate to severe renal impairment (CrCl <50 mL/min) as dose adjustment required","May cause confusion and other CNS effects, especially in elderly or renally impaired patients","May potentiate effects of warfarin, theophylline, and phenytoin via CYP inhibition"] |
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| No specific monitoring required; standard prenatal care. |
| Fertility Effects | No evidence of adverse effects on fertility in animal studies. |