Dosing and uses of Glyceryl trinitrate PO (nitroglycerin PO)
Adult dosage forms and strengths
capsule, extended release
- 2.5mg
- 6.5mg
- 9mg
Angina Pectoris (Prophylaxis)
ER capsule: Initial 2.5-6.5 mg PO q6-8hr
Titrate up to effec dose until limited by Se
Renal Failure
CrCl: 10-50 mg/min: Administer q24-72hr
CrCl<10 mL/min: Administer q72-96hr
Pediatric dosage forms and strengths
Not FDA approved
Geriatric dosage forms and strengths
Angina Pectoris (Prophylaxis)
ER capsule: Initial 2.5-6.5 mg PO q6-8hrTitrate up to effec dose until limited by Se
Glyceryl trinitrate PO (nitroglycerin PO) adverse (side) effects
Common
Headache
Hypotension
Tachycardia
Dizziness
Lightheadedness
Blurred vision
Flushing
N/V
Nervousness
Xerostomia
Serious
Methemoglobinemia (rare)
Syncope
Prolonged bleeding time
Exfoliative dermatitis
Unstable angina
Rebound hypertension
Thrombocytopenia
Warnings
Contraindications
Hypersensitivity, acute MI, severe anemia
Recent use (within several days) of PDE-5 inhibitors (eg, avanafil, sildenafil, tadalafil, or vardenafil) may cause dangerously low hypotension; the time course of the interaction appears to be related to the PDE-5 inhibitor half-life
Riociguat; coadministration may cause hypotension
Narrow angle glaucoma (controversial: may not be clinically significant)
Cautions
MI or CHF, alcohol use, increased ICP (eg, head trauma, cerebral hemorrhage; potential contraindication), hyperthyroidism, hypertrophic cardiomyopathy, increased IOP, postural hypotension, volume depletion, low systolic Bp
Do not change brands unintentionally as not all are bioequivalent Treat drug-induced headache with aspirin or acetaminophen
Provide nitrate-free interval (10-12 hr or overnight) to avoid development of tolerance
Angina long term prophylaxis, NOT for acute relief
Lack of burning/tingling does not indicate loss of potency
Discontinue if blurred vision occurs
Use supportive treatment in overdose
Pregnancy and lactation
Pregnancy category: C
Lactation: not known whether the drug crosses into breast milk, use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Glyceryl trinitrate PO (nitroglycerin PO)
Mechanism of action
Organic nitrate which causes systemic venodilation, decreasing preload
Cellular mechanism: nitrate enters vascular smooth muscle and converted to nitric oxide (NO) leading to activation of cGMP & vasodilation
Relaxes smooth muscle via dose-dependent dilation of arterial and venous beds to reduce both preload and afterload, and myocardial O2 demand
Also improves coronary collateral circulation. Lower BP, increase HR, occasional paradoxical bradycardia
Pharmacokinetics
onset: within 1- hr4
Duration antianginal effects: Up to 12 hr
Bioavailability: 38.5%
Protein Bound: 11-60%
Vd: 3 L/kg
Metabolism: Liver, extrahepatic sites: vascular wall, RBC
Metabolites: 1,3-glyceryl dinitrate, 1,2-glyceryl dinitrate, & glyceryl mononitrate (inactive)
Clearance: 5.5-11 L/min
Excretion: urine
Dialyzable: No
