Rowasa
Rowasa
Generic Name
Rowasa
Mechanism
- Rowasa (alopen) is a bile acid‑sequestering anion‑exchange resin.
- It binds primarily deoxycholic and chenodeoxycholic acids in the upper jejunum, forming insoluble salts that are excreted unchanged in the stool.
- By preventing reabsorption, it reduces intestinal motility and stimulates chloride and water absorption, thereby decreasing stool frequency and volume in secretory and infectious diarrhoea.
- Unlike many antidiarrheals, it has no systemic absorption or muscarinic, serotoninergic, or cytotoxic activity.
Pharmacokinetics
- Absorption: Negligible; essentially remains in the gut lumen.
- Distribution: No significant tissue distribution; the drug remains bound to bile acids.
- Metabolism: Not metabolized by hepatic enzymes.
- Excretion: Eliminated unchanged in the feces; half‑life of the resin is ~48–72 h (based on entero‑hepatic cycling).
- Drug interactions: As anion‑exchange resin, it can bind and reduce absorption of concomitant medications (e.g., warfarin, vitamin K, insulin, and azithromycin)—take tablets at least 2 h apart from other agents.
Indications
- Acute, non‑inflammatory diarrhoea (e.g., bacterial, viral, parasitic).
- Traveler’s diarrhoea (predominantly secretory).
- Chronic diarrhoea secondary to bile acid malabsorption (rare).
- Adjunct to triple‑therapy regimens for Clostridioides difficile with angiotensin‑II receptor blockers.
Contraindications
| Category | Considerations |
| Contraindications |
• Severe hepatic dysfunction (bilirubin >2 × ULN) • Choledocholithiasis or gallbladder disease • Total parenteral nutrition (TN N) without enteral access (no substrate) |
| Warnings |
• Caution in patients with hypertriglyceridemia or cholestasis (can worsen lipid‑profile). • Monitor for iron‑deficiency anemia and fat‑soluble vitamin‑deficiency (A, D, E, K) when used >2 weeks. |
| Drug‑Drug Interactions |
• Anticoagulants (warfarin) – ↑ INR; monitor. • Oral hypoglycemics – ↓ glycaemic control due to delayed drug absorption. |
| Special Populations |
• Pregnancy: Category C – limited data; use if benefits outweigh risks. • Lactation: excreted in breast milk minimal; use with caution. |
Dosing
| Condition | Adult Dose | Pediatric Dose | Remarks |
| Acute diarrhoea | 30 mg (1 tablet) ≤ 45 min before first loose stool; may repeat within 24 h | 0.5 mg/kg (max 30 mg) | Does not cure infection; reduces stool frequency. |
| Traveler’s diarrhoea | 5–10 mg orally once; continue until symptoms resolve or max 5 days | 0.2 mg/kg once daily | Can be combined with antibiotics (e.g., ciprofloxacin). |
| Chronic bile‑acid malabsorption | 10–20 mg daily | 0.2–0.3 mg/kg/day | Long‑term use; monitor lipid panel & vitamin status. |
| Use with antibiotics | Administer at least 2 h before or after to avoid binding. | Melt or chew to avoid aggregation of bile acids. |
• Tablet characteristics: 650 mg alopen; typical 30 mg dose represents 4.6 % of the tablet.
• Administration: Take with water; may improve tolerability.
• Rescue therapy: Oral rehydration solutions should be used concurrently.
Adverse Effects
| System | Common (≤ 10 %) | Serious (≤ 1 %) |
| Gastrointestinal | Nausea, bloating, flatulence, constipation, abdominal pain | GI obstruction, ileus |
| Hematologic | Anemia (low iron) | Severe myelosuppression (rare) |
| Metabolic | Hypercholesterolemia, hypertriglyceridemia | Severe lipid‐profile abnormalities |
| Vitamins | Fat‑soluble vitamin deficiency (A, D, E, K) | Coagulopathy from vitamin K deficiency |
| Others | Delayed onset of action (up to 4 hrs) | Severe cholestasis in predisposed individuals |
Monitoring
- Baseline & follow‑up: CBC, ferritin, iron studies (for chronic use).
- Lipid profile: Total cholesterol, LDL, triglycerides (surveillance every 3–6 months).
- Liver enzymes: ALT, AST, bilirubin (if hepatic disease or signs of dysfunction).
- Vitamin status: Serum vitamin D and E levels if therapy >2 weeks.
- Renal function: Not required; drug not renally cleared.
- Coagulation: INR when concurrent warfarin.
Clinical Pearls
1. Time‑sensitive dosing – Administer within 45 minutes of the first loose stool for optimum efficacy.
2. Resin‑binding caution – Separate Rowasa from other oral agents by ≥2 h to avoid sequestration.
3. Travelers' tip – When used prophylactically for traveler’s diarrhoea, start at 5 mg/d and increase to 10 mg if symptoms appear.
4. Cohabitant interaction – If a patient is on chloramphenicol or penicillins, pre‑emptively adjust dosage of those antibiotics due to inhibited absorption.
5. Malabsorption watch – For patients on long‑term Rowasa, consider periodic assessment for iron‑deficiency anemia and vitamin‑K‑related bleeding risk.
6. Contraindicated with NSAIDs – Use caution when co‑administered with bile‑acid‑sequestering NSAIDs, as stool volume may be accentuated.
7. Pregnancy – No large studies; the drug exerts minimal systemic exposure—utilized only when no safer antidiarrheals exist.
8. Rescue hydration – Always pair Rowasa with oral rehydration; it does not replace fluid loss.
9. Dose titration – Incrementally increase the dose for chronic bile‑acid malabsorption to mitigate lipid effects.
10. Forgotten warning – Despite the long half‑life, the resin is excreted entirely with feces; hence it should not be taken on a fasting day if no other dietary fat is available for bile acid cycling.
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