A 32-year-old woman presents with severe anal pain during and after defecation for 3 weeks, with visible blood on toilet paper. On examination, a linear tear is seen in the posterior midline of the anal canal. Which is the drug of choice for medical management of acute anal fissure?

Explanation

## Medical Management of Acute Anal Fissure **Key Point:** Glyceryl trinitrate (GTN) 0.2% ointment is the first-line pharmacological agent for acute anal fissure, with healing rates of 60–70% when applied topically twice daily. ### Mechanism of Action GTN causes smooth muscle relaxation in the internal anal sphincter by releasing nitric oxide, reducing anal resting pressure and improving blood flow to the fissure site, thereby promoting healing. ### Comparative Efficacy of Topical Agents | Agent | Mechanism | Healing Rate | Side Effects | Notes | |-------|-----------|--------------|--------------|-------| | **GTN 0.2%** | NO donor; IAS relaxation | 60–70% | Headache (10–20%) | **First-line** | | **Diltiazem 2%** | Calcium channel blocker; IAS relaxation | 60–65% | Minimal local irritation | Alternative if GTN headache | | **Nifedipine 0.3%** | Calcium channel blocker; IAS relaxation | 50–60% | Less effective than diltiazem | Third-line option | | **Hydrocortisone 1%** | Anti-inflammatory | 30–40% | Risk of skin atrophy | Adjunct only, not monotherapy | **High-Yield:** GTN headache (10–20% incidence) is the main limiting side effect, but it is dose-dependent and often resolves with continued use or dose reduction. ### Treatment Algorithm ```mermaid flowchart TD A[Acute Anal Fissure]:::outcome --> B[Conservative measures first]:::action B --> C[Stool softeners, high-fiber diet, sitz baths]:::action C --> D{Response in 2-4 weeks?}:::decision D -->|Yes| E[Continue conservative care]:::action D -->|No| F[Add topical GTN 0.2%]:::action F --> G{Healing at 8 weeks?}:::decision G -->|Yes| H[Discontinue GTN]:::action G -->|No| I[Switch to diltiazem or consider botulinum toxin]:::action I --> J{Persistent?}:::decision J -->|Yes| K[Lateral internal sphincterotomy]:::action ``` **Clinical Pearl:** GTN should be applied twice daily (morning and evening) for 8 weeks; discontinuation before 8 weeks increases recurrence risk. **Warning:** Do not use hydrocortisone or other corticosteroids as monotherapy for fissure — they do not address the underlying sphincter hypertonia and risk skin atrophy with prolonged use. [cite:Sabiston Textbook of Surgery Ch 28]