Usage
Mebendazole is an anthelmintic (anti-worm) medication prescribed for the treatment of various parasitic worm infections, including:
- Roundworm (Ascariasis)
- Hookworm (Ancylostomiasis, Necatoriasis, Uncinariasis)
- Pinworm (Enterobiasis, Oxyuriasis)
- Whipworm (Trichuriasis)
Its pharmacological classification is anthelmintic.
Mebendazole works by selectively inhibiting the synthesis of microtubules in intestinal worms. This disruption of microtubules affects the worms’ uptake of glucose, leading to energy depletion and ultimately their death.
Alternate Names
Mebendazole is also known by various brand names, including Vermox®, Ovex®, and Emverm™.
How It Works
Pharmacodynamics: Mebendazole acts locally in the intestine, with minimal systemic absorption. It primarily targets the parasitic worms by binding to their beta-tubulin, a protein that forms microtubules. These microtubules are essential for various cellular processes in the worms, including glucose uptake, intracellular transport, and cell division. By disrupting microtubule function, mebendazole leads to impaired glucose uptake, causing energy depletion and ultimately the death of the worm.
Pharmacokinetics: Mebendazole is poorly absorbed from the gastrointestinal tract. Food, especially high-fat meals, may increase absorption slightly. The small amount absorbed is extensively metabolized in the liver, primarily by the CYP450 enzymes. Mebendazole is mainly eliminated in the feces, with a small portion excreted in the urine. The elimination half-life of the parent drug and its metabolites is variable, ranging from 2.5 to 5.5 hours.
Dosage
Standard Dosage
Adults:
A single dose of 100 mg is recommended for pinworm infections, and this dose can be repeated in 2-4 weeks if necessary. For other worm infections (roundworm, hookworm, whipworm), 100 mg twice daily (morning and evening) for three consecutive days is the typical dosage.
Children:
The dosage for children over 2 years of age is the same as for adults. For children under 2 years old, the dosage and use should be determined by a doctor.
Special Cases:
- Elderly Patients: No specific dose adjustments are typically required. Monitor for potential adverse events.
- Patients with Renal Impairment: Caution is advised in patients with renal impairment. Dose adjustments may be necessary.
- Patients with Hepatic Dysfunction: Mebendazole is metabolized in the liver, so caution should be exercised in patients with hepatic impairment. Dosage adjustments might be required.
- Patients with Comorbid Conditions: Consider any potential drug interactions with other medications the patient might be taking.
Clinical Use Cases
The dosages provided are for general treatment of worm infections and not specifically applicable to the scenarios listed (intubation, surgical procedures, mechanical ventilation, ICU use, emergency situations). These settings are not standard situations where Mebendazole would be indicated or require specific dosing.
Side Effects
Common Side Effects
- Diarrhea
- Abdominal pain or discomfort
- Nausea
- Vomiting
- Loss of appetite
- Headache
- Dizziness
Rare but Serious Side Effects
- Allergic reactions (rash, hives, itching, swelling)
- Seizures
- Fever and chills
- Severe abdominal pain
- Bloody stools
- Unusual tiredness or weakness
- Jaundice
Long-Term Effects
Long-term side effects are uncommon with the usual short-term treatment of mebendazole.
Contraindications
- Hypersensitivity to mebendazole or any of its components.
- Pregnancy (first trimester; subsequent use should only be if clearly needed).
- Concomitant use with metronidazole.
Drug Interactions
- Cimetidine: May increase mebendazole plasma concentrations.
- Metronidazole: Concomitant use may increase the risk of Stevens-Johnson syndrome or toxic epidermal necrolysis.
- Phenytoin and Fosphenytoin: May decrease mebendazole levels.
Pregnancy and Breastfeeding
Mebendazole is generally avoided during the first trimester of pregnancy. Its use during the second and third trimesters should be considered only if the potential benefit outweighs the risk to the fetus. Limited data suggests it is excreted into breast milk in small amounts. However, it’s generally considered safe to use while breastfeeding.
Drug Profile Summary
- Mechanism of Action: Inhibits microtubule synthesis in worms, leading to energy depletion and death.
- Side Effects: Diarrhea, abdominal pain, nausea, vomiting, rare allergic reactions or seizures.
- Contraindications: Hypersensitivity, first trimester of pregnancy, concomitant use with metronidazole.
- Drug Interactions: Cimetidine, metronidazole, phenytoin.
- Pregnancy & Breastfeeding: Avoid in the first trimester; use with caution thereafter. Generally safe during breastfeeding.
- Dosage: 100 mg single dose (pinworm) or 100 mg twice daily for 3 days (other worm infections).
- Monitoring Parameters: Monitor for resolution of symptoms and recurrence of infection. In prolonged therapy or high doses, monitor complete blood count (CBC) and liver function tests (LFTs).
Popular Combinations
Mebendazole is typically used as a single agent. There are no widely recognized “popular” drug combinations.
Precautions
- Strict hygiene measures are crucial to prevent re-infection, including handwashing, cleaning of toilets, and laundering of bedding.
- Monitor patients with liver disease carefully.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Mebendazole?
A: For adults and children over 2 years, 100 mg as a single dose for pinworm infection; 100 mg twice daily for 3 days for other common worm infections.
Q2: How does Mebendazole work?
A: It inhibits microtubule formation in worms, affecting their glucose uptake and leading to their death.
Q3: What are the common side effects of Mebendazole?
A: Diarrhea, abdominal pain, nausea, and vomiting are the most common side effects.
Q4: Can pregnant or breastfeeding women take Mebendazole?
A: It should be avoided in the first trimester of pregnancy. Use with caution in later trimesters if benefits outweigh risks. It is generally considered safe during breastfeeding.
Q5: What should I do if the infection returns after treatment?
A: Retreatment after 2-4 weeks is often recommended for pinworm infections. Consult a doctor for other recurrent worm infections. Strict hygiene practices are essential.
Q6: Are there any serious side effects I should be aware of?
A: Although rare, serious side effects such as allergic reactions, seizures, and severe abdominal pain can occur. Seek medical attention immediately if these occur.
Q7: Does Mebendazole interact with other medications?
A: Yes, it can interact with cimetidine, metronidazole, and phenytoin. Inform your doctor of all medications you are taking.
Q8: Can Mebendazole be used in children?
A: Yes, for children over 2 years, the dosage is the same as for adults. For children under 2, consult a doctor.
Q9: Are there any dietary restrictions while taking Mebendazole?
A: No specific dietary restrictions are necessary. However, high-fat meals can slightly increase the absorption of the drug.
Q10: How is Mebendazole administered?
A: It is administered orally as a chewable tablet or can be crushed and mixed with a small amount of water for easier swallowing. It can be taken with or without food.
