Product InformationRegistration Status: Active
NARPAN TABLET 50mg is approved to be sold in Singapore with effective from 1998-09-15. It is marketed by DUOPHARMA (SINGAPORE) PTE LTD, with the registration number of SIN10002P.
This product contains Naltrexone 50mg in the form of TABLET. It is approved for ORAL use.
This product is manufactured by DUOPHARMA (M) SDN BHD in MALAYSIA.
It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.
Derivative of noroxymorphone that is the N-cyclopropylmethyl congener of naloxone. It is a narcotic antagonist that is effective orally, longer lasting and more potent than naloxone, and has been proposed for the treatment of heroin addiction. The FDA has approved naltrexone for the treatment of alcohol dependence.
Used as an adjunct to a medically supervised behaviour modification program in the maintenance of opiate cessation in individuals who were formerly physically dependent on opiates and who have successfully undergone detoxification. Also used for the management of alcohol dependence in conjunction with a behavioural modification program.
Mechanism of Action
Naltrexone is a pure opiate antagonist and has little or no agonist activity. The mechanism of action of naltrexone in alcoholism is not understood; however, involvement of the endogenous opioid system is suggested by preclinical data. Naltrexone is thought to act as a competitive antagonist at mc, κ, and δ receptors in the CNS, with the highest affintiy for the μ receptor. Naltrexone competitively binds to such receptors and may block the effects of endogenous opioids. This leads to the antagonization of most of the subjective and objective effects of opiates, including respiratory depression, miosis, euphoria, and drug craving. The major metabolite of naltrexone, 6-β-naltrexol, is also an opiate antagonist and may contribute to the antagonistic activity of the drug.
- Although well absorbed orally, naltrexone is subject to significant first pass metabolism with oral bioavailability estimates ranging from 5 to 40%.
- * 1350 L [intravenous administration]
- Hepatic. When administered orally, naltrexone undergoes extensive biotransformation and is metabolized to 6 beta-naltrexol (which may contribute to the therapeutic effect) and other minor metabolites.
* ~ 3.5 L/min [after IV administration]
In the mouse, rat and guinea pig, the oral LD50s were 1,100-1,550 mg/kg; 1,450 mg/kg; and 1,490 mg/kg; respectively. High doses of naltrexone (generally ≥1,000 mg/kg) produce salivation, depression/reduced activity, tremors, and convulsions.
17-(Cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxymorphinan-6-one | 17-(Cyclopropylmethyl)-4,5α-epoxy-3,14-dihydroxymorphinan-6-one | N-Cyclopropylmethyl-14-hydroxydihydromorphinone | N-Cyclopropylmethylnoroxymorphone | Naltrexon | Naltrexona | Naltrexone | Naltrexonum | Naltrexone |