Naltrexone Pharmacology


About Naltrexone
An opioid receptor(competitive antagonists at ?- and ?- receptor) antagonist, In alcohol dependence and opioid dependence.
Mechanism of Action of Naltrexone
Naltrexone is a competitive opioid antagonist. It reversibly and completely blocks all the opioid receptors (mu, kappa and delta). It is an orally administered long acting, pure opioid antagonist
Alcoholism: Opioid receptors are thought to be responsible for some of the reinforcing effects of alcohol.
Pharmacokinets of Naltrexone
Absorption: Naltrexone is well absorbed after oral administration.
Distribution: It is widely distributed in the body and only about 20 - 30 % is distributed in protein bound form
Metabolism: Naltrexone undergoes extensive first pass metabolism. Metabolites and the drug undergo enterohepatic recirculation.
Excretion: It is excreted mainly in the urine.
Onset of Action for Naltrexone
15 - 30 minutes
Duration of Action for Naltrexone
24 hours
Half Life of Naltrexone
4 hours
Side Effects of Naltrexone
1. Nausea
2. Vomiting
3. Abdominal pain
4. Constipation
5. Diarhoea
6. Headache
7. Anorexia
8. Insomnia
9. Anxiety
10. Nervousness
11. Depression
12. Increased thirst
13. Lethargy
14. Chest pain
15. Lymphocytosis
16. Muscle pain
17. Joint pain
18. Rashes
19. Fatigue
20. Sweating
21. Lacrimation
22. Delayed ejaculation
23. Decreased potency
24. Somnolence
25. Weight loss
Contra-indications of Naltrexone
1. Hypersensitivity to Naltrexone
2. Patient on Opioid therapy
3. Acute opioid withdrawal
4. Liver failure
Special Precautions while taking Naltrexone
1. Hepatic impairment
2. Renal impairment
Pregnancy Related Information
Use with caution
Old Age Related Information
Use with caution
Breast Feeding Related Information
Use with caution
Children Related Information
NEONATES: Contraindicated
Indications for Naltrexone
1. Opioid antagonist
2. Alcoholism
Interactions for Naltrexone
Disulfiram: The safety and efficacy of concomitant use of naltrexone and disulfiram has not been established. Concomitant use of two potentially hepatotoxic drugs is ordinarily not recommended.
Thioridazine: Lethargy and somnolence have been reported when naltrexone and thioridazine have been used.
Others: Patients taking naltrexone may not benefit from opioid containing medicines like cough and cold preparations, antidiarrhoeals and opioid analgesics. In an emergency, when opioid analgesia must be administered to a patient using naltrexone, the amount of opioid required might be greater than the usual dose and the resulting respiratory depression may be deeper and more prolonged.
Typical Dosage for Naltrexone
Adult: Initial dose: 25 mg / day, Maintenance dose: 50mg/day or 350mg / week given in 3 alternate days.
Alcoholism: Naltrexone 50 mg daily for 3 month
Schedule of Naltrexone
Storage Requirements for Naltrexone
Store at 15 - 30 degree C.Protect from heat and light. Keep out of the reach of children.
Effects of Missed Dosage of Naltrexone
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Naltrexone
Give supportive measures and symptomatic treatment.

Home Delivery for Naltrexone in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including naltrexone.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for naltrexone and other medicines and health products. Home delivery services for naltrexone may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take naltrexone only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for naltrexone before they complete the sale. You can get this information while placing the order for naltrexone with the pharmacy.

Naltrexone is a generic medicine name and there are several brands available for it. Some of the brands for naltrexone might be better known than naltrexone itself. If the pharmacy that's willing to deliver medicines to your home doesn't have naltrexone in stock, you can ask for one of the branded alternatives for naltrexone.