Dosing and uses of amyl nitrite
Adult dosage forms and strengths
liquid for inhalation
- 0.3 mL (0.85-103%) crushable glass ampule
Acute Relief of Angina
0.3 mL by inhalation of crushed ampule, may repeat q3-5min
Wave crushed ampule under nose multiple times for 2-6 nasal inhalations
Cyanide Poisoning
0.3 mL ampule crushed and contents poured onto a gauze and placed in front of patient's mouth or endotracheal tube, if patient intubated, to inhale over 15-30 sec; repeat qMin until IV sodium nitrite available
Each ampul lasts ~3 min; separate administration by at least 30 sec to allow patient to adequate oxygenate
Pediatric dosage forms and strengths
liquid for inhalation
- 0.3 mL (0.85-103%) crushable glass ampule
Angina Pectoris
Safety & efficacy not established
Cyanide Poisoning (Off-label)
0.3 mL ampule crushed and contents poured onto a gauze and placed in front of patient's mouth or endotracheal tube if patient intubated to inhale over 15-30 sec; repeat qMin until IV sodium nitrite available
Each ampul lasts ~3 min; separate administration by at least 30 sec to allow patient to adequate oxygenate
amyl nitrite adverse (side) effects
Frequency not defined
Common
- Dizziness
- Facial flushing
- Hypotension
- Tachycardia
- Vasodilation
- Headache restlessness
- Syncope
- Shock
- Nausea, vomiting
- IOP increased
- Orthostatic hypotension
Less Common
- Hemolytic anemia
- Methemoglobulinemia (high dose)
- Rash
- Weakness
Warnings
Contraindications
Hypersensitivity to organic nitrates
Recent use (last 24 hr) sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra) or other phopsphodiesterase-5 inhibitor use
Caution in narrow angle glaucoma (controversial: may not be clinically significant)
Severe anemia
Recent head trauma
Cautions
AMI, alcohol use, hyperthyroidism, cardiomyopathy, incr ICP (eg, head, trauma, cerebral hemorrhage-potential contraindication), incr IOP, postural hypotension, volume depletion, low systolic Bp
Inability to relieve chest pain after 3 doses may mean AMI-rush to ER if possible
Avoid excessive, prolonged hypotension
Withdraw gradually to avoid acute angina
Patient should be sitting down during & immediately after inhaling
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
Protect from light
Pregnancy and lactation
Pregnancy category: C (X for angina)
Lactation: Use caution; not known whether drug crosses into breast milk
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 amyl nitrite
Mechanism of action
Vasodilating agent
Relaxes smooth muscle via dose-dependent dilation of arterial and venous beds to reduce both preload and afterload, and myocardial O2 demand
Also improve coronary collateral circulation. Lower BP, incr HR, occasional paradoxical bradycardia
Cyanide Poisoning: Nitrite ions react with hemoglobin to form methemoglobin which unites with cyanide to form cyanomethemoglobin; this causes cytochrome oxidase to become free, which in turn allows aerobic metabolism to continue
Pharmacokinetics
Onset: 10-30 sec
Duration: 3-15 min (angina)
Peak: 3 min
