Effects
Nifedipine is an active ingredient of the dihydropyridine group and has a relaxing effect on vascular smooth muscle. When used topically or orally, it dilates blood vessels, improves blood flow and thus wound healing, is anti-inflammatory, and relieves anal sphincter spasms. Dihydropyridines inhibit the influx of calcium into smooth muscle cells by inhibiting L-type voltage-gated calcium channels, thereby inhibiting muscle contraction.
Indications
Nifedipine creams are used for local, external, and conservative treatment of anal fissures. To date, they are not available as finished products for this purpose, are not approved for this indication, and must be prepared as an extemporaneous formulation in a pharmacy equipped with a laboratory.
Dosage
As directed by the physician. The cream is applied three times a day with the finger in the anal canal all around. The treatment must be continuous for about 4 to 6 weeks. The dose used is small (about a pea-sized amount) and should not be exceeded to keep the risk of adverse effects low.
Preparation
In many countries, dosage forms containing 0.2% nifedipine in Excipial cream are in common use and have been shown by Spirig to remain stable for at least 3 to 6 months. However, it should be noted that gels and ointments and higher concentrations up to 0.5% have also been used in clinical studies. Excipial cream is now off the market.
| Nifedipine | 0.2 g |
| Excipial cream | ad 100.0 g |
Preparation is delicate and not feasible in every pharmacy. It should be noted that nifedipine is highly photosensitive. Therefore, it has been suggested to work in the dark under red light or to cover all lamps and windows with yellow kite paper. Pharmacies that do not manufacture the ointment themselves can order it from specialized service providers. Some hospital pharmacies also make it. Diltiazem, which has been used for local treatment of anal fissures, is also photosensitive.
Contraindications
The contraindications, precautions, and potential interactions of oral nifedipine therapy should also be followed for topical treatment as a precaution. Contraindications include hypersensitivity, pregnancy and lactation, cardiovascular shock, unstable angina, acute myocardial infarction (within the first 4 weeks), and combination with rifampicin. For complete precautions, see the drug label (eg, Adalat, Generic).
Adverse effects
Local skin reactions and hypersensitivity reactions are possible. Rarely, possible systemic adverse effects of nifedipine may occur, for example, oedema, low blood pressure, headache, and flushing. According to clinical studies, nifedipine creams are better tolerated than the nitroglycerin ointments also used to treat anal fissure, which often cause a headache called nitrate headache as an adverse effect.
