Glyceryl Trinitrate (nitroglycerine) Rectal prep
Indications
Glyceryl Trinitrate (nitroglycerine) Rectal prep is used for:
Chronic anal fissure
Adult Dose
Rectal Anal fissure As 0.4% oint: Apply 1.5 mg 12 hrly up to 8 wk applied to the anal canal.
Child Dose
Renal Dose
Administration
Gently insert the ointment into the anal canal using the finger. The finger with the ointment must be inserted to the first finger joint (approximately 1 cm) into the anus. Treatment may be continued until the pain goes away, or for up to a maximum 8 weeks.
Contra Indications
Do not use Glyceryl Trinitrate 0.4% ointment if the patients:
are allergic to glyceryl trinitrate or to similar medicines
suffer from low blood pressure
suffer from heart or blood vessel disorders
suffer from closed-angle glaucoma
suffer from migraine or recurrent headaches
suffer from increased intracranial pressure or high pressure within your skull
suffer from anaemia
are taking any of the following medicines: sildenafil citrate, tadalafil, vardenafil, medicines for angina or heart pain such as glyceryl trinitrate (GTN), isosorbide dinitrate, amyl or butyl nitrite, medicines for high blood pressure or depression (tricyclic anti-depressants), acetyl cysteine or alteplase
Precautions
Take special care with Glyceryl Trinitrate 0.4% ointment if patient has:
liver or kidney disease
to be given heparin
haemorrhoids (piles) and notice more bleeding than usual,
severe headaches when using ointment,
The ointment may lower blood pressure. Blood pressure is more likely to be lowered if drink alcohol whilst you are using ointment.
Ointment is not indicated for patients under the age of 18 years.
Pregnancy-Lactation
Interactions
Enhances bioavailability of dihydroergotamine. Glyceryl trinitrate infusion may prolong pancuronium-induced neuromuscular blockade. May reduce the efficacy of heparin, alteplase and noradrenaline when used together. Efficacy of buccal and sublingual preparations may be reduced by drugs that can cause dry mouth due to decreased dissolution. Aspirin and other NSAIDs may reduce the therapeutic response to glyceryl trinitrate.
Potentially Fatal: Orthostatic hypotension may be produced by combined use of calcium channel blockers, antihypertensives, phenothiazines and TCAs. Alcohol may cause severe hypotension and collapse.
Adverse Effects
Side effects of Glyceryl Trinitrate (nitroglycerine) Rectal prep :
Headache is the most common side-effect when glyceryl trinitrate 0.4% ointment is used. Other side-effects include dizziness, faintness on standing, light-headedness, blurred vision and tiredness & nausea.
Mechanism of Action
Glyceryl trinitrate acts on the enzyme nitric oxide stimulating guanylate cyclase in the vascular smooth muscle cells resulting in the relaxation of smooth muscles. It reduces venous return (preload) and facilitates subendocardial blood flow with redistribution into ischaemic areas. It relieves coronary vasospasm and dilates arterioles reducing afterload. It is useful for relief and prevention of anginal attacks.