NITRO-BID
Clinical safety rating
cautionComprehensive clinical and safety monograph for NITRO-BID (NITRO-BID).
Nitroglycerin is a nitrate that relaxes vascular smooth muscle by conversion to nitric oxide (NO), which activates guanylate cyclase, increasing cyclic guanosine monophosphate (cGMP) levels, leading to vasodilation. Primarily dilates veins, reducing preload and myocardial oxygen demand; also dilates coronary arteries.
| Metabolism | Rapidly metabolized via hepatic glutathione-organic nitrate reductase to dinitrates and mononitrates; also metabolized in erythrocytes and vascular tissue. |
| Excretion | Renal: <1% unchanged; extensive metabolism followed by renal excretion of metabolites, with minor biliary/fecal elimination (<5%). |
| Half-life | Terminal half-life of nitroglycerin is 1-4 minutes; clinical effects are short-lived due to rapid redistribution and metabolism. |
| Protein binding | Approximately 60% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | Vd approximately 3.3 L/kg, indicating extensive distribution into tissues beyond plasma volume. |
| Bioavailability | Sublingual: ~40% (high first-pass hepatic metabolism); Transdermal: ~72% (bypasses first-pass); Oral: <10% due to extensive hepatic metabolism. |
| Onset of Action | Sublingual: 1-3 minutes; Transdermal: 30-60 minutes; Intravenous: immediate (1-2 minutes); Topical (ointment): 15-30 minutes. |
| Duration of Action | Sublingual: 30-60 minutes; Transdermal: up to 12 hours with patch removal; Intravenous: as long as infusion continues; Topical: 3-6 hours. |
| Molecular Weight | 227.09 |
| Action Class | Urinary Antiseptic-Nitrofurantoin |
| Brand Substitutes | Utab 100mg Tablet SR, Nitrobest Tablet SR, Utichek 100mg Tablet SR, Nifutin Tablet SR, Nifnext SR Tablet |
Sublingual: 0.3-0.6 mg at onset of angina, may repeat every 5 minutes up to 3 doses. Transdermal: 0.2-0.8 mg/hour patch applied daily for 12-14 hours, then removed for 10-12 hours.
| Dosage form | INJECTABLE |
| Renal impairment | No specific adjustment required; nitroglycerin is minimally renally excreted. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: consider dose reduction (25-50% of normal dose). Child-Pugh C: avoid or use with extreme caution; reduce dose by 50% or more. |
| Pediatric use | Not routinely recommended; limited data. Intravenous: start at 0.25-0.5 mcg/kg/min, titrate by 0.5-1 mcg/kg/min every 3-5 min to effect; max 5 mcg/kg/min. |
| Geriatric use | Start at lower end of dosing range due to increased sensitivity and risk of hypotension. Sublingual: 0.3 mg initial. Transdermal: 0.2 mg/hour initially. |
| 1st trimester | Limited human data; use only if clearly needed. Animal studies have not revealed evidence of teratogenicity. |
| 2nd trimester | Use with caution; may cause maternal hypotension and reduced placental perfusion. |
| 3rd trimester | Use with caution; may cause maternal hypotension and reduced placental perfusion, potential fetal bradycardia. |
Clinical note
Comprehensive clinical and safety monograph for NITRO-BID (NITRO-BID).
| Placental transfer | Nitroglycerin crosses the placenta; extent not well quantified. Rapid metabolism limits fetal exposure. |
| Breastfeeding | Nitroglycerin is excreted into breast milk in small amounts. No adverse effects reported in nursing infants. Use with caution, especially in preterm infants or those with G6PD deficiency. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category C. Animal studies have shown fetal harm (bradycardia, reduced birth weight). Inadequate human data for first trimester; avoid unless benefit outweighs risk. Second and third trimesters: associated with maternal hypotension and fetal bradycardia; use only if clearly needed. |
| Fetal Monitoring | Monitor maternal blood pressure and heart rate continuously during infusion. Fetal heart rate monitoring recommended, especially during third trimester. Assess for signs of methemoglobinemia if high doses or prolonged use. |
| Fertility Effects | No specific human data on fertility impairment. Animal studies have not shown effects on fertility. Theoretical risk due to hemodynamic changes, but no established impact. |
■ FDA Black Box Warning
No FDA boxed warning specifically for NITRO-BID. However, nitroglycerin is contraindicated with phosphodiesterase-5 inhibitors (e.g., sildenafil) due to severe hypotension.
| Serious Effects |
Hypersensitivity to nitratesConcomitant use with phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)Severe anemiaIncreased intracranial pressure (e.g., head trauma, cerebral hemorrhage)Constrictive pericarditisCardiac tamponadeSevere hypotension (systolic BP <90 mmHg)Acute myocardial infarction with low filling pressure
| Precautions | May cause severe hypotension, especially with volume depletion; avoid in patients with hypertrophic cardiomyopathy; use caution in hepatic/renal impairment; tolerance develops with chronic use; may aggravate angina when discontinuing abruptly. |
| Food/Dietary | Avoid alcohol as it may cause hypotension. No specific food interactions; maintain usual diet. |
| Clinical Pearls | NITRO-BID (nitroglycerin ointment) is used for prophylaxis of angina pectoris. Apply to hairless skin, preferably chest or upper arm. Rotate sites to avoid irritation. Do not rub in; spread thin layer. Tolerance develops with continuous use; remove at bedtime to provide nitrate-free interval. Avoid in patients with severe hypotension, hypertrophic obstructive cardiomyopathy, or concurrent use of phosphodiesterase-5 inhibitors (e.g., sildenafil). |
| Patient Advice | Apply the prescribed amount to skin, do not rub in. · Wash hands after application. · Rotate application sites to prevent skin irritation. · Remove the ointment at bedtime to prevent tolerance. · Store at room temperature away from heat and open flame. · Seek emergency care if chest pain persists after use. |
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