A fixed-dose combination (FDC) of an anti-filarial agent (Diethylcarbamazine) and a second-generation antihistamine (Cetirizine). Primarily used for the treatment and prophylaxis of lymphatic filariasis (caused by Wuchereria bancrofti and Brugia malayi) while managing the associated allergic and inflammatory symptoms (Mazzotti reaction) that occur due to the death of microfilariae. Cetirizine helps mitigate the pruritus, rash, and angioedema that can accompany DEC therapy.
Adult: One tablet (Diethylcarbamazine 300mg + Cetirizine 10mg) orally, once daily. For MDA: A single dose annually. For treatment: 6mg/kg/day in divided doses for 12 days, often given as this FDC once daily.
Note: Take after food to minimize gastric upset. Tablet can be taken with a full glass of water. For MDA programs, administration is directly observed. Do not crush or chew unless advised.
Diethylcarbamazine (DEC) immobilizes microfilariae by altering their surface membranes, making them susceptible to host phagocytosis. It also damages adult worms. Its exact molecular target is unclear but may involve arachidonic acid metabolism. Cetirizine is a potent and selective antagonist of peripheral H1 receptors, inhibiting the histamine-mediated allergic response triggered by dying microfilariae.
Pregnancy: Category C (US FDA). DEC: Animal studies show risk, human data insufficient. Use only if benefit outweighs risk, especially in endemic areas for MDA. Cetirizine: Category B. Generally considered safer. Avoid in first trimester unless absolutely necessary. Consult physician.
Driving: May impair ability to drive or operate machinery. Caution advised, especially during initial therapy or if drowsiness occurs. Do not drive if feeling sedated.
| CNS Depressants (Alcohol, Benzodiazepines, Opioids) | Additive sedative effect with Cetirizine | Major |
| Theophylline | May decrease DEC's clearance, increasing risk of DEC toxicity | Moderate |
| Other Antihistamines (e.g., Hydroxyzine, Diphenhydramine) | Additive anticholinergic and sedative effects | Moderate |
| Drugs prolonging QT interval (e.g., Erythromycin, antipsychotics) | Theoretical risk of additive QT prolongation with Cetirizine (low risk at 10mg) | Moderate |
| Mebendazole/Albendazole | Often co-administered in MDA for synergistic anti-helminthic effect. No major pharmacokinetic interaction known. | Minor |
Same composition (Diethylcarbamazine (300mg) + Cetirizine (10mg)), different brands: