ALBENZA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ALBENZA (ALBENZA).
Albendazole is a benzimidazole carbamate that inhibits tubulin polymerization by binding to the colchicine site of β-tubulin, disrupting microtubule formation. This leads to impaired uptake of glucose and depletion of glycogen stores, resulting in immobilization and death of susceptible helminths.
| Metabolism | Primarily metabolized by hepatic microsomal enzymes, specifically to albendazole sulfoxide (active metabolite) via CYP3A4 and possibly other CYP isoforms. Further metabolized to albendazole sulfone (inactive) and other metabolites. |
| Excretion | Primarily biliary/fecal (less than 2% renal as unchanged drug and metabolites; most eliminated via bile into feces as metabolites). |
| Half-life | Terminal elimination half-life of albendazole sulfoxide (active metabolite) is 8-12 hours; albendazole itself has a very short half-life (<1 hour) due to extensive first-pass metabolism. |
| Protein binding | Albendazole: ~70% bound to plasma proteins (mainly albumin). Albendazole sulfoxide: ~70% bound. |
| Volume of Distribution | Albendazole sulfoxide: 0.8-1.2 L/kg, indicating extensive tissue distribution including bile and CSF. |
| Bioavailability | Oral: Poor bioavailability (~5-10%) of parent drug due to extensive first-pass metabolism; enhanced (up to 5-fold) with high-fat meal. Not administered parenterally. |
| Onset of Action | Oral: Onset of anthelmintic effect occurs within hours to days depending on parasite susceptibility; clinical improvement may take days to weeks. |
| Duration of Action | Duration of action is approximately 24-48 hours for a single oral dose; multiple doses are often required for systemic infections due to tissue penetration and life cycle stages. |
400 mg orally twice daily for 60 days for neurocysticercosis; 400 mg orally once daily for 3 days for pinworm; 400 mg orally once daily for 3 days for hookworm, roundworm, whipworm; 400 mg orally twice daily for 3 days for tapeworms; 400 mg orally twice daily for 7 days for giardiasis.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (CrCl <30 mL/min); use with caution. |
| Liver impairment | Contraindicated in patients with known cirrhosis (Child-Pugh C). For mild to moderate hepatic impairment (Child-Pugh A or B), monitor liver function; dose adjustment not established. |
| Pediatric use | For children ≥2 years: 400 mg orally twice daily for 60 days for neurocysticercosis; 400 mg orally once daily for 3 days for pinworm; 400 mg orally once daily for 3 days for hookworm, roundworm, whipworm; 400 mg orally twice daily for 3 days for tapeworms; 400 mg orally twice daily for 7 days for giardiasis. For children <2 years: not recommended. |
| Geriatric use | No specific dose adjustment recommended; use with caution due to potential hepatic and renal decline. Monitor for adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ALBENZA (ALBENZA).
| Breastfeeding | Albendazole is excreted into human breast milk. The milk-to-plasma (M/P) ratio is approximately 0.1. Due to potential adverse effects in nursing infants (e.g., bone marrow suppression, hepatic effects), caution is advised. The manufacturer recommends discontinuing breastfeeding or the drug, taking into account the importance of the drug to the mother. |
| Teratogenic Risk | Albendazole is contraindicated in pregnancy, especially during the first trimester. It has been shown to be embryotoxic and teratogenic in animals. In humans, there are reports of congenital malformations when used during pregnancy, including craniofacial defects and limb abnormalities. Use is not recommended in women who are or may become pregnant. |
■ FDA Black Box Warning
NOT FDA APPROVED FOR ANY INDICATION IN THE UNITED STATES. (Note: This warning applies as Albendazole is not FDA-approved for use in the US; however, it is marketed elsewhere. In the US, it is available under an investigational protocol or as a compounded product.)
| Serious Effects |
["Hypersensitivity to albendazole or benzimidazole compounds.","Pregnancy (Category D) and lactation.","Pre-existing hepatic disease or unexplained liver function test abnormalities.","Bone marrow depression or severe neutropenia."]
| Precautions | ["Bone marrow suppression: Monitor blood counts regularly; risk of agranulocytosis, pancytopenia.","Hepatotoxicity: Elevation of liver enzymes; contraindicated in patients with hepatic disease or abnormal liver function tests.","Neurotoxicity: Risk of seizures, especially in neurocysticercosis due to inflammatory response to dying parasites.","Carcinogenicity: Long-term use associated with increased risk of tumors in animal studies.","Pregnancy: Category D (positive evidence of human fetal risk); avoid use in pregnant women or those likely to become pregnant."] |
| Food/Dietary |
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| Fetal Monitoring | If use in pregnancy is unavoidable (e.g., treatment of life-threatening infection), perform serial ultrasound to assess fetal anatomy and growth. Monitor maternal liver function tests and complete blood counts due to risk of hepatotoxicity and bone marrow suppression. Assess fetal well-being with non-stress tests or biophysical profiles as appropriate. |
| Fertility Effects | Albendazole has been associated with reversible impairment of spermatogenesis in animal studies. In humans, data are limited; however, it may cause transient oligospermia or reduced sperm motility. Effects on female fertility are not well documented. |
| Albendazole absorption is enhanced by fatty foods; a high-fat meal increases plasma concentration of the active metabolite albendazole sulfoxide by up to 5-fold. Avoid grapefruit juice as it may alter metabolism via CYP3A4 inhibition. Fatty meals are recommended to maximize efficacy. |
| Clinical Pearls | Albendazole is a broad-spectrum anthelmintic effective against intestinal and tissue nematodes, cestodes, and some protozoa. It is poorly absorbed orally; co-administration with a fatty meal significantly increases bioavailability (up to 5-fold). Monitor liver function tests periodically due to risk of hepatotoxicity. Contraindicated in pregnancy (category C) and in patients with known hypersensitivity. For neurocysticercosis, concomitant corticosteroids and antiepileptics are often required to manage inflammatory reactions. May cause bone marrow suppression; obtain CBC at baseline and periodically. Dose adjustment not needed in renal impairment but caution in hepatic impairment. |
| Patient Advice | Take with a high-fat meal to increase absorption. · Complete the full course of therapy even if symptoms improve. · Use effective contraception during treatment and for at least 1 month after the last dose. · Report any signs of liver problems: yellowing of skin/eyes, dark urine, right upper quadrant pain. · May cause dizziness; avoid driving or operating machinery if affected. · Notify your healthcare provider if you experience persistent sore throat, fever, or unusual bleeding/bruising. |