Choice of the benzimidazole drug for treatment of cystic echinococcosis :



Mebendazole, albendazole and flubendazole are used in the treatment of cystic echinococcosis. The success rate with flubendazole was very low (10) and therefore it is not considered a suitable drug for treatment of this disease. Mebendazole is the first benzimidazole drug used for treatment of cystic echinococcosis and success rate of 7-38% was reported for it. (3,4,10,11) In studies directly comparing mebendazole with albendazole, the success rate for albendazole was much greater (average 21%-30% versus 7%). (8,10-14) This was attributed to better bioavailability and greater tissue and cyst penetration of Albendazole. (5,6,8,15) According to available data, albendazole can be considered as the drug of choice for medical treatment of cystic echinococcosis. (5,8)


Dosage :

Mebendazole is given in doses of 40-50mg/kg/day, usually in three divided doses. (13,14,17-19). According to clinical experience, daily doses of greater than 6g should not be applied to adults regardless of serum level achieved. (7) Albendazole is given in daily dose of 10-15mg/kg/day. (10,11,17,19). Animal studies showed that a total daily dose of 10mg/kg/day of albendazole produces cyst fluid concentrations of albendazole sulfoxide in excess of 100µg/l, which is at the lower end of effective in-vitro parasiticidal concentrations. (15) Because of problems related to available dosage forms of the drug (400mg human and 600mg veterinary tablets), patients with body weight equal to or greater than 40kg receive 400mg bid and in those < 40kg, dose is calculated according to body weight. It seems that efficacy of chemotherapy is higher in patients who received higher doses of albendazole (10,16) or mebendazole. (10,18) The maximum daily dose of albendazole given in experimental studies is 20mg/kg. (16)

Duration & method of treatment:

For mebendazole the recommended duration of treatment is 3 months. (10,12) It is suggested that longer durations of treatment (up to 6 months) may be more effective and should be considered in cases predicted to be poorly responsive to antihelminthic therapy. (18) Albendazole is given in an intermittent treatment schedule with 4 week courses of therapy separated by drug free intervals of 2 weeks to decrease the incidence of adverse effects. (7) Usually three courses of therapy are given and it seems that more than six courses are usually not necessary. (1,10,17,19) Gill- Grande et al showed that 3 months of treatment is significantly more effective then 1 month course in reducing the viability of protoscolices (6% versus 24%). (20) There are emerging evidences that continuous treatment with albendazole for 3 to 6 month without drug holidays is significantly more effective and may not be associated with increased side effects. (1,7,8,12,21)