Atrex40 mg/5 ml

Atrex is an anthelmintic (antiparasitic) medicine used for the treatment of intestinal worm (helminth) infections.

Established/Approved Uses

• Ascariasis (roundworm infection caused by Ascaris lumbricoides) — this is the primary and most well-established indication for Atrex.
• Hookworm infection (Ancylostoma duodenale and Necator americanus), particularly light to moderate infections; Atrex is less effective against heavy hookworm burden and severe infections may need a repeat dose or an alternative anthelmintic.

Other Reported Uses (Variable Evidence)

• Infections with Enterobius vermicularis (threadworm/pinworm), Trichuris trichiura (whipworm), Strongyloides stercoralis, and Trichostrongylus species have been reported to respond to Atrex, though efficacy against these organisms is generally lower and less consistent than against ascariasis.

Historical/Discontinued Use — Not a Current Indication

Atrex was formerly used at low doses as an immunomodulatory adjunct to chemotherapy (fluorouracil) in colon cancer, and it has also been used in veterinary medicine. These uses have been withdrawn/discontinued in human medicine in many countries, including removal of the cancer-adjunct product from the market, because of the risk of serious agranulocytosis. Atrex is not recommended and should not be used for these purposes; its current, marketed human use is as an anthelmintic for intestinal worm infection.

Each tablet/capsule of Levamisole typically contains Levamisole hydrochloride equivalent to 40 mg or 50 mg of Levamisole base (strength varies by manufacturer). Levamisole is also available as an oral suspension/syrup, typically containing Levamisole hydrochloride equivalent to 40 mg of Levamisole base per 5 mL. Please check the product label of the specific brand dispensed, as exact strength and inactive ingredients vary by manufacturer.

Atrex is a synthetic imidazothiazole derivative used as an anthelmintic (antiparasitic) agent. It is the pharmacologically active levo-isomer of tetramisole.

Atrex acts by paralyzing susceptible nematode (roundworm) parasites through depolarizing neuromuscular blockade, which causes the worms to detach from the intestinal wall and be expelled from the body in the stool by normal gut motility, usually within 24 hours of dosing.

Atrex is administered orally, usually as a single dose, and is well absorbed from the gastrointestinal tract.

Atrex belongs to the anthelmintic (antiparasitic) class of drugs, specifically the imidazothiazole group of anthelmintics.

Levamisole is the active levo-isomer of tetramisole. Its primary anthelmintic action is due to a depolarizing, ganglion-stimulant type neuromuscular blocking effect on susceptible nematodes, which causes irreversible paralysis of the worm's musculature.

Once paralyzed, the worms lose their grip on the intestinal wall and are expelled from the gastrointestinal tract by normal peristalsis, largely intact, generally within 24 hours.

Levamisole also has immunomodulatory properties — it can restore depressed immune function (particularly T-cell mediated responses) — but this action is not the basis for its current approved anthelmintic use and low-dose immunomodulatory use has been discontinued in human medicine due to safety concerns (see Precautions and Warnings).

Pharmacokinetics: Levamisole is rapidly and well absorbed after oral administration, with peak plasma concentrations reached in 1.5–2 hours. It is extensively metabolized in the liver, and metabolites are excreted mainly in the urine, with a plasma elimination half-life of approximately 3–4 hours.

Atrex is for oral use only.

• Take Atrex preferably after a light meal to reduce the chance of stomach upset.
• Swallow tablets whole with water; the oral suspension should be measured with an accurate measuring device (not a household spoon).
• Shake the oral suspension well before use.
• Atrex is usually given as a single dose; follow your physician's instructions regarding any repeat dosing.
• Avoid alcohol during and for a few days after taking Atrex (see Interactions).

The following clinically significant interactions have been reported with Atrex:

• Alcohol: Atrex can cause a disulfiram-like reaction (facial flushing, nausea, vomiting, palpitations) when alcohol is consumed during treatment. Avoid alcohol during and for a few days after taking Atrex.
• Phenytoin: Atrex may increase plasma levels of phenytoin, increasing the risk of phenytoin toxicity; monitor phenytoin levels/clinical status if co-administered.
• Warfarin and other coumarin anticoagulants: Atrex may potentiate the effect of warfarin, increasing bleeding risk; monitor coagulation parameters (e.g., INR) if used together.
• Other anthelmintics: Atrex has been reported to increase the bioavailability of ivermectin and to decrease the bioavailability of albendazole when co-administered; avoid combining anthelmintics unless specifically directed by a physician.

Always inform your physician or pharmacist about all medicines, supplements, and alcohol use before starting Atrex.

Side effects of Atrex are generally infrequent, mild, and transient when used at the recommended single anthelmintic dose.

Common Side Effects

• Nausea, vomiting
• Abdominal pain/cramps
• Dizziness (giddiness)
• Headache
• Metallic taste
• Diarrhea

Rare but Serious Side Effects

• Agranulocytosis — a serious drop in white blood cells that increases infection risk; this is rare with standard short-course anthelmintic dosing but is a well-documented, serious risk with repeated or prolonged use (see Precautions and Warnings).
• An encephalopathy-like syndrome (confusion, altered consciousness, seizures) occurring 2–3 weeks after treatment has been reported rarely.
• Skin rash or hypersensitivity reactions.
• Transient fever, particularly in patients with concurrent microfilaraemia.

Seek prompt medical attention for fever, sore throat, unusual bruising/bleeding, mouth ulcers, or signs of infection during or after taking Atrex, or for any severe or persistent symptoms.

Pregnancy: Atrex is generally not recommended during pregnancy. Although animal reproduction studies have not shown clear teratogenic effects, adequate and well-controlled studies in pregnant women are lacking. Atrex should be used in pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus; consult a physician before use.

Lactation: It is not well established whether Atrex passes into breast milk. Caution is advised, and Atrex should be used during breastfeeding only if clearly needed and under medical supervision, weighing the benefits of treatment against any potential risk to the nursing infant.

Agranulocytosis Risk

Serious agranulocytosis (a marked drop in a type of white blood cell, increasing susceptibility to infection) has been reported with Atrex, particularly with repeated dosing or prolonged/higher-dose use in its former immunomodulatory application; this led to withdrawal of Atrex for non-anthelmintic uses in several countries. Although this risk is much lower with the short, single-dose anthelmintic regimen, patients and caregivers should watch for fever, sore throat, mouth ulcers, unusual bruising or bleeding, or signs of infection during or shortly after treatment, and seek prompt medical attention if these occur. Do not repeat doses of Atrex more often than prescribed.

Neurological Effects

Rare cases of encephalopathy and, in the context of prolonged/repeated exposure (including illicit drug contamination scenarios not related to standard medical dosing), multifocal inflammatory leukoencephalopathy have been associated with Atrex. With standard short-course anthelmintic dosing, this risk appears very low, but caregivers should seek medical attention promptly if confusion, unusual movements, seizures, or altered consciousness occur after treatment.

Alcohol

Avoid alcohol during and for several days after taking Atrex, due to the risk of a disulfiram-like reaction.

Hepatic Impairment

Use with caution in patients with significant liver disease, as Atrex is extensively metabolized by the liver.

General

Complete the course of Atrex exactly as directed by the physician; do not use more frequently, in higher doses, or for longer than prescribed, and do not share this medicine with others without medical advice, as unsupervised repeated use increases the risk of serious blood-related side effects.

Overdose of Atrex may cause exaggeration of its known side effects, such as nausea, vomiting, abdominal pain, dizziness, and headache; neurological symptoms (confusion, seizures) may occur with significant overdose.

There is no specific antidote for Atrex overdose. If overdose is suspected, seek immediate medical attention or contact a poison control center/emergency services. Treatment is supportive and symptomatic, based on medical assessment; do not attempt home treatment for a suspected overdose.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Renal Impairment

No well-established dose adjustment is required for renal impairment; however, use with caution and under medical supervision in patients with significant renal disease.

Hepatic Impairment

Use with caution in patients with significant hepatic impairment, since Atrex is extensively metabolized by the liver; consult a physician for individualized dosing.

Elderly

No specific dose adjustment has been established for elderly patients; use the standard adult dose with routine clinical monitoring.

Immunocompromised Patients

Use with caution and close monitoring in patients with pre-existing blood disorders or immunosuppression, given the rare but serious risk of agranulocytosis associated with Atrex (see Precautions and Warnings).

Atrex is typically given as a single dose for standard intestinal worm infections. For heavy or persistent hookworm infection, a physician may advise a single repeat dose 1–7 days after the first dose. Atrex is not intended for continuous or long-term daily use; repeated courses, if needed, should only be taken on medical advice, spaced appropriately, and should not be self-directed by the patient.

Levamisole belongs to the imidazothiazole class of anthelmintic (antiparasitic) agents.

Levamisole, the active levo-isomer of tetramisole, causes depolarizing neuromuscular blockade in susceptible nematode parasites, leading to persistent muscular contraction and irreversible paralysis of the worm. The paralyzed worm can no longer maintain its grip on the intestinal mucosa and is expelled from the gastrointestinal tract by normal peristaltic movement, usually within 24 hours of dosing.

Atrex is used in children for treatment of intestinal worm infections, with weight/age-based single dosing as outlined in Dosage and Administration:

• 1–4 years: 40 mg (1 tablet or 5 mL suspension) as a single dose.
• 5–15 years: 80 mg (2 tablets or 10 mL suspension) as a single dose.

Safety and efficacy of Atrex in children under 1 year of age have not been well established; use in this age group only if specifically advised by a physician after weighing benefits and risks. Caregivers should monitor children for fever, sore throat, or signs of infection after dosing, given the rare risk of agranulocytosis, and should not repeat doses without medical advice.