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Albendazole: Observational and Comparative studies

Albendazole: Observational studies

Ankylostomicisis

Albendazole has been used in the treatment of human hookworm and trichuriasis. In a mass-treatment report from Western Australia 295 individuals in a remote rural area were treated with albendazole 400 mg/day for 5 days because of possible Giardia lamblia and hookworm infections. The 37% prevalence of Giardia fell to 12% between days 6 and 9, but rose again to 28% between days 18 and 30.

The effect on hookworms (Ankylostoma duodenale) was more pronounced and more sustained with a reduction of the pretreatment prevalence of hookworm infections from 76% before treatment to 0% after 3^1 weeks. The tolerability of the drug was judged to be excellent by 89%, good by 1%, and moderately good by 1%, while 9% gave no response. Adverse effects were reported by five individuals and consisted of mild abdominal pain, mild or moderate diarrhea, moderate fever, and weakness.

Ascariasis

The efficacy of 2 years of mass chemotherapy against ascariasis has been evaluated in Iran. A single dose of albendazole 400 mg was given at 3-month intervals for 2 years to every person, except children under 2 years of age and pregnant women. After 2 years of treatment the prevalences, based on 2667 post-treatment samples, had fallen (Table. There were no adverse effects of mass treatment with albendazole.

Echinococcosis

Hydatid disease is a common zoonosis caused by the larval cysts of Echinococcus granulosus. Hydatid cysts most commonly form in the liver, but can occur in any organ. The management and operative complications in 70 patients with hydatid disease aged 10-78 years have been studied retrospectively to assess the impact of albendazole and praziquantel compared with surgery. In all, 39 patients received albendazole and praziquantel in combination and 19 received albendazole alone; none was treated with praziquantel alone.

The combined use of albendazole and praziquantel preoperatively significantly reduced the number of cysts that contained viable protoscolices. During the 12-year follow-up period an initial 3 months of drug treatment (albendazole throughout and praziquantel for 2 weeks), re-assessment, followed by either surgery or continuation with chemotherapy was found to be a rational treatment algorithm. In 11 patients albendazole, given for a median of 3 months at a dose of 400 mg bd, had adverse effects: five patients developed nausea and six had abnormal liver function tests. Therapy was withdrawn in two patients owing to altered liver function.

The efficacy of albendazole emulsion has been studied in 212 patients with hydatid disease of the liver, aged 4-82 years. Two regimens of albendazole were given for a variable period (3 months to more than 1 year); 67 adults received albendazole 10 mg/kg/day and 145 adults received 12.5 mg/kg/day. The overall cure rate was 75%. In the follow-up study the recurrence rate was 10%.

The highest cure rate was observed in those who received albendazole 12.5 mg/kg/day for 9 months. At the start of therapy about 15% of the patients had mild pruritus, rash, and transient gastric pain, which resolved without specific therapy. Two patients had alopecia. There were frequent rises in serum transaminase activities in both groups but not to above 30-50 IU/1, except in six patients, who had values above 200 IU/1. In two patients albendazole was withdrawn because of vomiting. In one patient who took 12.5 mg/kg/day severe adverse effects, such as anorexia, jaundice, anemia, edema, and hypoproteinemia, developed, necessitating withdrawal. Reintroduction of albendazole 10 mg/kg/day was uneventful.

The use of albendazole and mebendazole in patients with hydatidosis has been evaluated in 448 patients with E. granulosis hydatid cysts who received continuous treatment with albendazole 10-12 mg/kg/day for 3-6 months daily orally in a total dose of (323 patients) twice or mebendazole 50 mg/kg/day. At the end of treatment, 82% of the cysts treated with albendazole and 56% of the cysts treated with mebendazole showed degenerative changes. During long-term follow-up 25% of these cysts showed relapse, which took place within 2 years in 78% of cases.

Further treatment with albendazole induced degenerative changes in over 90% of the relapsed cysts, without induction of more frequent or more severe adverse effects, as observed during the first treatment period. Adverse effects during the first treatment period consisted of raised transaminases with albendazole (67 of 323 patients) and mebendazole (16 of 125 patients), and abdominal pain in 12 and 11% respectively.

With both drugs, occasional patients experienced headache, abdominal distension, vertigo, urticaria, jaundice, thrombocytopenia, fever, or dyspepsia, but most of these are known manifestations of Echinococcus infection. Six of 323 patients taking albendazole withdrew because of adverse effects compared with eight of 125 patients taking mebendazole. It appears that albendazole is more effective than mebendazole in the treatment of hydatid cysts caused by E. granulosis and that both the intensity and frequency of the usually mild adverse effects are comparable.

Filariasis

Treatment of patients with high Loa loa microfilaraemia is sometimes complicated by an encephalopathy, suggested to be related to a rapid killing of large number of L. loa microfilariae. If the L. loa microfilarial count could be reduced more slowly, before ivermectin is distributed, ivermectin-related encephalopathy might be prevented. In 125 patients with L. loa microfilariasis the effect of albendazole (800 mg/day for three consecutive days) or multivitamin tablets on L. loa microfilarial load and the occurrence of encephalopathy were studied. L. loa microfilarial loads were followed for 9 months.

There was no significant change in the overall microfilarial loads among those treated with albendazole, although the loads in patients with more than 8000 microfilariae/ml tended to fall more progressively during the first 3 months of follow-up. There were no cases of encephalopathy. The main adverse effects reported were itching (in eight patients taking albendazole and seven taking multivitamins), abdominal pain (two taking albendazole), and diarrhea (one taking albendazole, two taking multivitamins); overall analysis showed no significant difference in these events between the groups.

Albendazole was associated with modest but significantly raised plasma transaminase activities.

Neurocysticercosis

In a report on the use of albendazole 15 mg/kg/day in two divided doses for 14 days in the treatment of persistent neurocysticercosis, adverse reactions were monitored in 43 patients with seizures and a solitary cysticercal cyst, who had not been treated before. In all patients CT scans confirmed the presence of a solitary cyst less than 2 cm in diameter.

Antiepileptic treatment was continued. In seven patients dexamethasone 8 mg/day in four divided doses was given for the first 5-7 days after the start of treatment. Follow-up CT scans at 4-10 weeks after the start of treatment showed responses in 20 patients, with complete disappearance in seven patients and a reduction to 50% of the pretreatment size in the other 13.

There were adverse effects in 15 patients, with a maximum on the fifth day after the start of treatment. Six patients had severe headaches, 11 had partial seizures, and 2 had epileptic seizures and severe postictal hemiparesis that persisted for a week or more. Because of these serious adverse effects treatment was discontinued in seven patients and dexamethasone was added in those patients who were not already taking it, although its use proved questionable. Adverse effects were seen in three of seven patients who took prophylactic steroid therapy and in 12 of 36 patients who did not.

Albendazole was effective in neurocysticercosis in an optimal dosage of 15 mg/kg/day divided in two doses every 12 hours for 8 days. It was generally well tolerated, although several patients had adverse reactions during the first few days after the start of treatment, consisting of headache, vomiting, and exacerbation of neurological symptoms caused by an inflammatory reaction to antigens from degenerating cysts, necessitating the concomitant use of glucocorticoids. In very large cysticerci, or cysticerci located in risky areas like the brain-stem, these reactions may rarely be life-threatening.

Protozoal infections

The efficacy of albendazole 800 mg bd for 14 days for persistent diarrhea due to cryptosporidiosis, isosporiasis, or microsporidiosis has been studied in 153 HIV-positive patients. Albendazole reduced the burden of protozoal infection and promoted mucosal recovery in 87 patients who had a complete clinical response. Two patients reported nausea and vomiting. One patient developed leukopenia (1.9 x 109/1) after treatment and four patients developed thrombocytopenia (51-98 x 109/1).

Toxocariasis

The efficacy of albendazole plus prednisolone has been studied in five patients aged 11-72 years with ocular toxocariasis. All had uveitis and retinochoroidal granulomas. Their symptoms had persisted for a mean of 14 months (range 3 days to 24 months). The adults were treated with albendazole 800 mg bd for 2 weeks plus prednisolone starting at 1.5 mg/kg/day tapering over 3 months. The children were treated with 400 mg bd for 2 weeks plus prednisolone 1.0 mg/kg/day. All tolerated the therapy well without adverse effects. In particular, there were no significant hypersensitivity reactions to dying Toxocara larvae. The uveitis resolved in all cases and there were no relapses. After treatment, all the granulomas had disappeared, leaving heavily pigmented chor-ioretinal scars without loss of vision.

Albendazole: Comparative Studies

The use of albendazole and mebendazole in patients with hydatidosis has been evaluated in 448 patients with E. granulosis hydatid cysts who received continuous treatment with albendazole 10-12 mg/kg/day for 3-6 months daily orally in a total dose of (323 patients) twice or mebendazole 50 mg/kg/day. At the end of treatment, 82% of the cysts treated with albendazole and 56% of the cysts treated with mebendazole showed degenerative changes. During long-term follow-up 25% of these cysts showed relapse, which took place within 2 years in 78% of cases.

Further treatment with albendazole induced degenerative changes in over 90% of the relapsed cysts, without induction of more frequent or more severe adverse effects, as observed during the first treatment period. Adverse effects during the first treatment period consisted of raised transaminases with albendazole (67 of 323 patients) and mebendazole (16 of 125 patients), and abdominal pain in 12 and 11% respectively.

Headache occurred in eight patients taking albendazole and three taking mebendazole, abdominal distension in seven and five patients, vertigo in five and one, urticaria in five and three, jaundice in one and one, thrombocytopenia in two and none, fever in three and none, dyspepsia in two and four, and tachycardia in two and none. Six of 323 patients taking albendazole withdrew because of adverse effects compared with eight of 125 patients taking mebendazole. It appears that albendazole is more effective than mebendazole in the treatment of hydatid cysts caused by E. granulosis and that both the intensity and frequency of the usually mild adverse effects are comparable.

In a randomized trial in Mexico 622 children with Trichuris were randomized to either albendazole 400 mg/day for 3 days, one dose of albendazole 400 mg, or one dose of pyrantel 11 mg/kg. The aim was to study efficacy and the effects on growth.

After three courses at 1 year the level of infection with Trichuris was reduced by 99% in the 3-day albendazole treatment group, by 87% in the single-dose albendazole treatment group, and by 67% in the pyrantel group. There were no significant differences in the increases in height, weight, or arm circumference, but contrary to expectations there was a lower increase in the thickness of the triceps skin fold in those given 3-day courses of albendazole. This was only found in the patients with lower pretreatment Trichuris stool egg counts.

These findings suggest that although elimination of Trichuris may promote growth in children, albendazole in a dose of 1200 mg/kg every 4 months may have an independent negative effect on growth. In an accompanying commentary it was concluded that the suggestion that relatively high doses of albendazole may affect growth deserves study, but that this possible effect must be weighed against the negative effect of prolonged helminthic infestation on children’s health, growth, and cognitive function. However, it is unlikely that high-dose treatment will be standard in mass-treatment campaigns, and these results should not deter the use of single-dose albendazole in mass-treatment programs in high-risk populations.

In 110 children with ascariasis or trichuriasis the efficacy of a single dose of albendazole 400 mg has been compared with that of nitazoxanide 100 mg bd for 3 days in children aged 1-3 years and 200 mg bd for 3 days in children aged 4-11 years. Nitazoxanide cured 89 and 89% of the cases of ascariasis and trichuriasis respectively. Albendazole cured 91 and 58% of the cases of ascariasis and trichuriasis respectively.

Abdominal pain, nausea, diarrhea, and headache were reported as mild adverse effects in 105 patients who took nitazoxanide, and abdominal pain, nausea, and vomiting were reported as adverse effects in 54 patients who took albendazole. All the adverse events were mild and transient and drug withdrawal was not necessary.

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