Professional reference for pharmacists preparing extemporaneous products. Follow your jurisdiction’s compounding standards, use a validated formulation where available, and prefer a licensed product (Rectogesic, Rectiv 0.4%) when appropriate.
Quick reference
- Formula: nitroglycerin 2% ointment 1 part + white soft paraffin 9 parts (w/w) = 0.2%.
- 30 g: 3 g of 2% + 27 g base. 60 g: 6 g + 54 g.
- Method: geometric dilution on a slab or in an ointment mill; label with strength, directions and beyond-use date.
Why 0.2% and how it is used
A chronic anal fissure is a split in the lining of the anal canal kept open by spasm of the internal sphincter, which reduces blood flow. Topical nitroglycerin releases nitric oxide, relaxing the sphincter and improving blood flow so the fissure can heal. UK guidance (NICE CKS) recommends topical glyceryl trinitrate (GTN) 0.4% (Rectogesic, licensed) for chronic fissures, applied twice daily for up to 8 weeks; 0.2% preparations, made extemporaneously, are also widely used and may cause fewer headaches. In the US, Rectiv 0.4% is the licensed product, and 0.2% is a common compounded strength.
| Final quantity |
Nitroglycerin 2% ointment |
White soft paraffin |
Final strength |
| 30 g |
3 g |
27 g |
0.2% |
| 50 g |
5 g |
45 g |
0.2% |
| 60 g |
6 g |
54 g |
0.2% |
| 30 g (0.4%) |
6 g |
24 g |
0.4% |
Calculation: C1 × M1 = C2 × M2 → 2% × M1 = 0.2% × 30 g → M1 = 3 g. Source products include Nitro-Bid 2% ointment (US); availability of a 2% base product varies by country, and some pharmacies use a validated formula from GTN in a suitable solvent instead. Use the formula your standards require.
Compounding method
- Weigh the 2% ointment and the white soft paraffin accurately.
- Place the 2% ointment on an ointment slab (or in a mortar) and add an approximately equal amount of paraffin; levigate until uniform.
- Continue adding paraffin in amounts roughly equal to the mixture already present (geometric dilution) until all is incorporated.
- Pass through an ointment mill if available for uniformity.
- Pack into an airtight, light-resistant tube or jar; close promptly (nitroglycerin is volatile).
- Wear gloves throughout: nitroglycerin is absorbed through the skin and causes headaches in the person compounding.
| Label item |
Example |
| Name and strength |
Glyceryl trinitrate (nitroglycerin) 0.2% w/w ointment |
| Directions |
Apply a pea-sized amount (about 1 cm) to the anal margin two or three times daily, as directed |
| Warnings |
May cause headache or dizziness; do not use with sildenafil, tadalafil or vardenafil; wash hands after use |
| Storage |
Store below 25 °C; keep tightly closed |
| Beyond-use date |
Per your standards (for example USP <795> nonaqueous preparations: up to 90 days, or shorter per evidence) |
Patient counselling points
- Use a finger cot or glove, and apply just inside or at the edge of the anus.
- Headache is common in the first days; paracetamol can help; sit or lie down if dizzy.
- Don’t use with erectile dysfunction medicines (PDE-5 inhibitors): risk of a severe drop in blood pressure.
- Avoid in severe anaemia, raised intracranial pressure, and certain heart conditions unless advised.
- Keep stools soft with fibre and fluids; continue for the full course (typically 6–8 weeks).
- See the doctor if there’s bleeding that doesn’t settle, no improvement after 8 weeks, or symptoms that suggest something other than a fissure.
Other dilutions and practical notes are in the clinical pharmacy notes.
Frequently asked questions
What base is used for 0.2% GTN ointment?
White soft paraffin (white petrolatum) is the usual diluent for paraffin-based 2% ointment. Some formulations use other bases; keep to a validated formula.
Is diltiazem cream an alternative?
Yes. Diltiazem 2% ointment or cream is another first-line option for chronic anal fissure, with fewer headaches; it is also usually compounded.
How much 0.2% ointment is applied per dose?
Commonly about 1 cm (roughly 0.25–0.5 g), two or three times daily, as prescribed.
Sources and further reading
CanforaMedicine Guide
