NITROGLYCERIN, TOPICAL
Chemistry - Famous as an explosive, nitroglycerin (NTG) occurs undiluted as a thick, volatile, white-pale yellow flammable, explosive liquid with a sweet, burning taste. The undiluted drug issoluble in alcohol and slightly soluble in water. Because of obvious safety reasons, nitroglycerin isdiluted with lactose, dextrose, propylene glycol, alcohol, etc. when used for pharmaceuticalpurposes. Nitroglycerin may also be called glyceryl trinitrate, or nitroglycerol.
Contraindications/Precautions - Nitrates are contraindicated in patients with severe anemia orwho are hypersensitive to them. They should be used with caution (if at all) in patients with cerebralhemorrhage or head trauma. Nitrates should be used with caution in patients with diuretic-inducedhypovolemia or with other hypotensive conditions
Overdosage - If severe hypotension results after topical administration, wash site of application toprevent any more absorption of ointment. Fluids may be administered if necessary. Epinephrine iscontraindicated as it is ineffective and may complicate the animal's condition.
Storage, Stability, Compatibility
For storage/stability and compatibility for dosage forms otherthan the topical ointment, see specialized references or the package inserts for each product. Thetopical ointment should be stored at room temperature and the cap firmly attached.Pharmacology - NITROGLYCERIN, TOPICAL
Nitroglycerin relaxes vascular smooth muscle primarily on the venous side, but adose related effect on arterioles may also occur. Preload (left end-diastolic pressure) is reducedfrom the peripheral pooling of blood and decreased venous return to the heart. Because of its arteriolar effects, afterload may also be reduced depending on the dose. Myocardial oxygen demandand workload are reduced and coronary circulation can be improved.Uses, Indications
Topical nitroglycerin in small animal medicine is used primarily as an adjunctive vasodilator in heart failure and cardiogenic edema. It is also used as an anti-anginal agent, an antihypertensive (acute), and topically to treat Raynaud's disease in humans.Pharmacokinetics - NITROGLYCERIN, TOPICAL
Nitroglycerin topical ointment is absorbed through the skin, with an onset ofaction usually within 1 hour and a duration of action of 2-12 hours. It is generally dosed in dogsand cats q6-8 hours (tid-qid). Nitroglycerine has a very short half-life (1-4 minutes in humans) andis metabolized in the liver. At least two metabolites have some vasodilator activity and have longerhalf-lives than NTG.Contraindications/Precautions - Nitrates are contraindicated in patients with severe anemia orwho are hypersensitive to them. They should be used with caution (if at all) in patients with cerebralhemorrhage or head trauma. Nitrates should be used with caution in patients with diuretic-inducedhypovolemia or with other hypotensive conditions
Adverse Effects, Warnings
Most common side effects seen are rashes at the application sitesand orthostatic hypotension. If hypotension is a problem, reduce dosage. Transient headaches are acommon side effect seen in humans and may be a problem for some animals.Overdosage - If severe hypotension results after topical administration, wash site of application toprevent any more absorption of ointment. Fluids may be administered if necessary. Epinephrine iscontraindicated as it is ineffective and may complicate the animal's condition.