Products
Rectogesic ointment is approved in many countries (some countries: Rectiv). Nitroglycerin ointments are also used in a higher concentration for transdermal treatment of angina (2%). This article refers to rectal administration for anal fissure.
Structure and properties
Nitroglycerin or glycerol trinitrate (C3H5N3O9, Mr = 227.1 g/mol) is nitrated glycerol. Pure nitroglycerin is explosive and the active principle of dynamite.
Synthesis
Effects
Nitroglycerin (ATC C05AE01) is a vasodilator and muscle relaxant. It relaxes the internal anal sphincter when used topically, improves blood flow, and thus has a moderate analgesic effect and improves wound healing.
Indications
Nitroglycerin ointments are used for pain management in chronic anal fissures.
Dosage
According to the package insert. The ointment is applied twice daily with the finger all around the anal canal. The duration of treatment is limited to 8 weeks. A fingerstall or cling film should be used for administration.
Contraindications
Nitroglycerin ointments are contraindicated in hypersensitivity, concomitant treatment with phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil) and nitric oxide donors, hypotension, hypovolemia, increased intracranial pressure, headache and migraine, certain cardiovascular diseases, severe anemia, and glaucoma. For complete precautions, see the drug label.
Interactions
Other vasodilator drugs, antihypertensives, and acetylcysteine may further lower blood pressure. Phosphodiesterase-5 inhibitors and NO donors are contraindicated. The effects of heparin may be attenuated. Other interactions are possible with alteplase and dihydroergotamine.
Adverse effects
Nitroglycerin is absorbed into the circulation, dilates blood vessels, and therefore very commonly causes headache (nitrate headache) and may lower blood pressure, resulting in hypotension. Other possible adverse effects include dizziness, nausea, diarrhea, rectal bleeding, itching, and burning.
