The internal anal sphincter to be palpated and injected with a 27-gauge needle while the patient lying on his or her left side. Each patient will receive 0.4 ml of solution containing botulinum toxin (for a total of 20 U), administered as two injections of equal volume (0.2 ml), one on each side of the anterior midline of the internal anal sphincter. No sedation or local anesthesia to be used during the procedure)

0.2 percent nitroglycerin ointment applied twice daily for six weeks.

Botox injection to be injected in internal anal sphincter to see the curative response in comparison to gtn cream application

All the patients will undergo a pretreatment evaluation that will include clinical inspection of the fissure based on evidence of posterior circumscribed ulcer, with a large sentinel tag of skin, induration at the edges, and exposure of the horizontal fibers of the internal anal sphincter and symptoms including post-defecatory or nocturnal pain, bleeding, or both. Then they will be randomized to receive treatment with either botulinum toxin or 0.2 percent nitroglycerin ointment applied twice daily for six weeks. The outcome in each group will be evaluated clinically.The end point of the study would be complete healing after treatment. The treatment will be considered successful if the fissure healed. Persistence of the fissure in the absence of symptoms will be considered as symptomatic improvement.The Secondary endpoints will measurement of post defecatory pain on Visual analogue scale (VAS) at each visit.