Common Anal Conditions · Version 2.0
Appendix B — Medication Safety Quick Reference
Dr. Tamer Rushdy Elalfy · 5 min read
Typical adult doses. Check every dose against the national formulary, product labelling, renal and hepatic function, age, weight, pregnancy and breastfeeding status, and interactions [L].
Table B.1 — Indications, doses, and adverse effects
| Medicine | Indication | Usual adult dose | Key adverse effects |
|---|---|---|---|
| Psyllium (ispaghula) | Constipation; haemorrhoids; fissure; firming loose stool | About 3.5 g once or twice daily, titrated; each dose with ≥ 150 mL water | Bloating, flatulence; obstruction if fluid is inadequate |
| Macrogol (PEG 3350); lactulose; magnesium salts | Constipation; impaction (macrogol) | Macrogol 1–3 sachets daily (impaction regimen per formulary); lactulose 15 mL twice daily, titrated | Bloating and cramps (lactulose); electrolyte disturbance; hypermagnesaemia (magnesium) |
| Stimulant laxatives (senna, bisacodyl) | Constipation; opioid-induced constipation | Senna 7.5–15 mg at night; bisacodyl 5–10 mg at night | Cramps, diarrhoea, hypokalaemia with overuse |
| Enemas and suppositories | Rectal loading; disimpaction | Glycerol suppository; bisacodyl 10 mg suppository; tap-water or mineral-oil enema; sodium phosphate enema single dose only | Rectal irritation; phosphate: hyperphosphataemia, hypocalcaemia, AKI |
| Topical lidocaine (2% gel, 5% ointment) | Pain of fissure or haemorrhoids; before examination | Thin layer; short courses; do not exceed product maximum | Contact dermatitis; systemic toxicity with large mucosal doses |
| Topical diltiazem 2% / nifedipine 0.2–0.3% | Chronic fissure (preferred first-line) | Pea-sized amount to the anal margin twice daily (some protocols three times) for 6–8 weeks | Local itch or burning; headache uncommon |
| Topical GTN 0.4% | Chronic fissure | About 2.5 cm of ointment (≈ 1.5 mg GTN) every 12 hours for up to 8 weeks | Headache (common), dizziness, hypotension |
| Topical corticosteroids | Short-term itch and oedema | Low-potency (for example hydrocortisone 1%), thin layer, ≤ 2 weeks | Atrophy, dermatitis, candida, masking of cancer |
| Oral flavonoids (MPFF, diosmin–hesperidin) | Acute haemorrhoidal symptoms (where licensed) | Per local labelling (commonly 3 g/day for 4 days, then 2 g/day for 3 days) [L] | GI upset, headache |
| Antibiotics for anorectal sepsis | Adjunct after drainage (cellulitis, systemic signs, immunosuppression); necrotising infection | Per local antibiogram [L]: e.g. amoxicillin–clavulanate 625 mg three times daily, or ciprofloxacin 500 mg twice daily + metronidazole 400–500 mg three times daily; severe sepsis: Table 5.3 | C. difficile, rash; QT prolongation and tendinopathy (quinolones) |
| Anticoagulants and antiplatelets | Around banding, excision, and surgery | Plan with the prescriber [L]: warfarin often stopped ~5 days (INR < 1.5); DOACs 1–3 days by drug, renal function, and bleeding risk; P2Y12 inhibitors 5–7 days if stoppable; aspirin often continued | Delayed bleeding (days 5–10) after banding; thrombosis if stopped inappropriately |
| Loperamide | Loose stool; faecal incontinence | Incontinence: 2 mg, titrated; acute diarrhoea: 4 mg then 2 mg after each loose stool (max 16 mg/day) | Constipation, ileus; QT prolongation and arrhythmia in overdose |
| SGLT2 inhibitors | Diabetes, heart failure, CKD | — | Genital infections; Fournier’s gangrene (rare, FDA 2018); euglycaemic DKA |
Table B.2 — Interactions, special populations, and when to avoid
| Medicine | Major interactions | Pregnancy / breastfeeding | Renal / hepatic | Avoid when |
|---|---|---|---|---|
| Psyllium | May reduce absorption of other drugs — separate by about 2 h | Suitable | Caution in fluid restriction | Impaction, obstruction, dysphagia, poor fluid intake |
| Osmotic laxatives | Magnesium chelates quinolones and tetracyclines | PEG and lactulose suitable | Avoid magnesium in CKD | Obstruction |
| Stimulant laxatives | Additive hypokalaemia with diuretics or steroids | Short-term use | — | Obstruction; acute abdomen |
| Enemas and suppositories | Phosphate + ACE inhibitors, ARBs, diuretics, NSAIDs | Avoid phosphate enemas | Avoid phosphate in CKD | Neutropenia, severe thrombocytopenia, suspected perforation or obstruction; arachis oil in peanut allergy (Appendix C) |
| Topical lidocaine | Additive with other local anaesthetics or class I antiarrhythmics | Suitable short-term | Caution with large doses in liver disease | Allergy; prolonged use |
| Topical diltiazem / nifedipine | Minimal systemic effect | Limited data — usually defer | — | Allergy |
| Topical GTN | PDE5 inhibitors (24–48 h), riociguat — contraindicated | Limited data — generally avoid | — | Severe aortic or mitral stenosis, HOCM, raised intracranial pressure, hypotension |
| Topical corticosteroids | — | Short-term low potency acceptable | — | Infection, undiagnosed ulcer or plaque, > 2 weeks |
| Oral flavonoids | Few known | Limited data | — | As a substitute for colon evaluation |
| Antibiotics | Warfarin effect ↑ (metronidazole, ciprofloxacin); quinolone chelation with Mg, Ca, Fe | Avoid quinolones and tetracyclines in pregnancy | Renal dose adjustment (amoxicillin–clavulanate, ciprofloxacin, carbapenems, vancomycin) | As a substitute for drainage |
| Anticoagulants / antiplatelets | NSAIDs, SSRIs increase bleeding | Specialist advice | DOAC accumulation in renal impairment (especially dabigatran) | Stopping after recent stents or with mechanical valves without cardiology input |
| Loperamide | QT-prolonging drugs; CYP3A4/P-gp inhibitors raise levels | Occasional use | Caution in hepatic impairment | Overflow or impaction, C. difficile, dysentery, bloody diarrhoea, fever, colitis, children with bloody diarrhoea |
| SGLT2 inhibitors | — | Avoid in pregnancy | Per indication and eGFR | Stop immediately if perineal infection is suspected; stop 3 days (ertugliflozin 4 days) before elective surgery per labelling; withhold when acutely unwell or fasting |