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Anal fissure medical treatment
One of the predisposing factors for the development of anal fissure is the increased sphincter tone. That is why researchers have been purposing numerous topical, oral and injectable agents to lower the resting pressure and therefore – relax the sphincter until the fissure is healed. Some of the most popular agents include – glyceryl trinitrate (GTN/nitroglycerin), calcium channel blockers – diltiazem or nifedipine, and botulinum toxin, which is injected locally. The available comparative data shows mixed results. However, most authors agree that all these agents are useful and can be employed as first-line treatment of anal fissures. Some even talk about “pharmacologic sphincterotomy”. Each agent has its proponents. The glyceryl trinitrate has been very popular during the 90s, but it has some drawbacks. Topical treatment with GTN may cause some side effects, such as headache. The calcium channel blockers have demonstrated similar effectivity with lower frequency of side effects. There is less data available on these agents, but they have a growing support. Botulinum toxin injections are also frequently applied for acute fissures. The efficacy of the pharmaceutical treatment falls in long-standing anal fissures. Surgical treatment has proven to be more effective in curing chronic fissures, with much less recurrences recorded.
Glyceryl trinitrate (nitroglycerin/GTN) for treatment of anal fissure
Many researchers have tried to demonstrate the beneficial effects of glyceryl trinitrate (GTN) for treatment of anal fissures. The GTN acts as a nitric oxide, which is the predominant neurotransmitter in the internal anal sphincter. The idea is that the release of nitric oxide is aiding the relaxation of the internal anal sphincter. Clinical trials have shown that the topical application of 0.2% glyceryl trinitrate ointment will lead to reduction of the pressure in the anal sphincter and thus promote faster fissure healing. The topical glyceryl trinitrate agent is to be applied for 4-8 weeks, with dosing frequencies varying from two to three times a day. The ointment should be applied inside the anal canal. Available data shows that it promotes healing in about 40-70% of the chronic anal fissures. Recurrence rates are relatively low (20-30%). Chronic anal fissures with a long-standing history are less likely to heal (>6 months). However, the application of GTN has been associated with some significant adverse effects. Headache has been reported as the primary side effect from nearly 70% of the patients. Due to the headaches some patients might find it difficult to continue the treatment. In this case the physician might prescribe another topical solution.
Calcium Channel Blockers for treament of anal fissure
Given the high frequency of side effects reported by patients treated with GTN, researchers have started to evaluate the effects of calcium channel blockers (nifedipine or diltiazem) for treatment of anal fissures. Diltiazem (DTZ) is primarily used in the treatment of hypertension and some types of arrhythmia. It relaxes the smooth muscles in the walls of arteries, which improves the blood flow and lowers the blood pressure. The idea is that diltiazem can be used to lower the resting anal pressure and promote fissure healing.
The agent is available as oral preparation and in topical form. Studies have shown that the topical treatment with 2% diltiazem cream is much more effective and it will promote healing in about 60-70% of the fissures. The diltiazem solution is to be applied inside the anal canal every 12 h, preferably once in the morning after defecation and once in the evening. The main side effects of the treatment with diltiazem are mild headaches, flushing of the face (or the limbs). The reports of side effects are very inconsistent, but they are to be expected in about 10-40% of the patients.
Nifedipine is a medication used to manage angina and high blood pressure. It’s usually administrated in oral form, but a topical solution can be prepared. Controlled trials have shown that topical nifedipine gel is much more effective in treatment of anal fissures than other commercial gels and ointments available (usually containing lidocaine and hydrocortisone). Trials with 0.2% nifedipine gel applied inside the anal canal every 12 hours have demonstrated improvement in 60% of the patients.
Topical treatment with diltiazem (or nifedipine) is usually administrated for 4 to 8 weeks. If there is no effect, the physician might purpose a surgical treatment. Comparative studies have shown that GTN and the calcium channel blockers can both promote healing of anal fissures. The side effects are the main concern in GTN treatment and most researchers agree that the topical application of diltiazem(or nifedipine) should be preferred as first-line treatment.
Botulinium Toxin (BT) injection for treatment of anal fissure
Botulinum toxin (also known as Botox®) is a product of the diverse group of pathogenic bacteria clostridium botulinum. The relaxation effects of the botulinum toxin on the local muscles been examined extensively. Several researchers have suggested that it could be used in the treatment of anal fissures. The toxin is injected the internal anal sphincter and causes paresis that lasts for weeks. This leads to a decrease in the anal resting pressure and promotes fissure healing.
The method of injection and the injection site of the botulinum toxin agent aren’t very well determined. Some physicians inject it in the external sphincter muscle and other inject it in the internal. One of the primary pathogenesis in anal fissure formation is the high resting pressure of the internal sphincter. That’s why the injection should be made in the internal sphincter. In patients with posterior fissure the injection could be made anteriorly. The botox injection is well tolerated and easy to perform as an outpatient procedure, that doesn’t require any time off. However, there is certain controversy over the safety and the side effects of the treatment with botulinum toxin. Skin and allergic reactions, perianal hematomas and other complications have been recorder after treatment with BT injection. Temporary incontinence has been noted in about 5% of the patients. Another problem is that there is no agreement on the optimal dose, which should be administrated. Some physicians are suggesting that 20 units injection of botulinum toxin should be used. If the fissure persist, higher doses can be administrated.
Different studies have demonstrated that the botox injection is effective in about 70% of the cases. We can conclude that it’s more effective than the topical treatment, but less effective than the operative solution. Relatively high recurrence rate has been recorded in the long run (30-50%).