Naltrexone

Opiates iateract with three principal classes of opioid GPCRs )J.-selective for the endorphiQS,5-selective for enkephalins, and K-selective for dynorphias (51). AU. three receptors have been cloned. Each inhibits adenylate cyclase, can activate potassium channels, and inhibit A/-type calcium channels. The classical opiates, morphine and its antagonists naloxone (144) and naltrexone (145), have moderate selectivity for the. -receptor. Pharmacological evidence suggests that there are two subtypes of the. -receptor and three subtypes each of the 5- and K-receptor. An s-opiate receptor may also exist. 

R = CH2CHCH2), and naltrexone [16590-41 -3] C2QH23NO4 (10, ), are both derived from oxymorphone (Table 2) and exhibit agonist... 

A common strategy for treating chronic opiate addiction iavolves the substitution of methadone which can either be provided as maintenance therapy or tapered until abstinence is achieved. Naltrexone and buprenorphine [52485-79-7] have also been used ia this manner. The a2 adrenergic agonist clonidine [4205-90-7] provides some rehef from the symptoms of opiate withdrawal, probably the result of its mimicking the inhibitory effect of opiates on the activity of locus coerukus neurons. 

Naltrexone hydrochloride dihydrate (l-7V-cyclopropylmethyl-7,8-dihydro-14-hydroxy-morphinan-6-one hydrochloride) [16676-29-2] M 413.9, m 274-276°, [a] -173° (c 1, H2O), pKEst(i) 6 (N-cyclopropylmethyl), pKEst(i) (phenolic OH). This narcotic antagonist has been purified by recrystn from MeOH and dried air. The free base has m 168-170° after recrystn from Me2CO. [Cone et al. J Pharm Sci 64 618 7975 Gold et al. Med Res Rev 2 211 7952.]... 

Another agent of this general type is nalmefene (47) Despite their useful characteristics, opiates display tolerance, addiction, abuse, and some toxic side effects Antagonists combat some of these effects, most notably respiratory depression and addiction Nalmefene reputedly has significant oral activity as a narcotic antagonist The synthesis of nalmefine concludes by Wittig olefination of naltrexone (46) to nalmefene (47) This molecular transformation resulted in a significant increase in oral potency as well (141... 

Substitution therapy with methadone or buprenorphine has been veiy successfiil in terms of harm reduction. Some opiate addicts might also benefit from naltrexone treatment. One idea is that patients should undergo rapid opiate detoxification with naltrexone under anaesthesia, which then allows fiuther naltrexone treatment to reduce the likelihood of relapse. However, the mode of action of rapid opiate detoxification is obscure. Moreover, it can be a dangerous procedure and some studies now indicate that this procedure can induce even more severe and long-lasting withdrawal symptoms as well as no improvement in relapse rates than a regular detoxification and psychosocial relapse prevention program. 

Alfentanil, codein, dihydromorphine, etor-phine, fentanyl, heroin, hydromorphone, levo-methadone, morphine, oxycodone, pethidine, piritramide, remifentanil, sufentanil, tilidine, tramadol Buprenorphine, pentazocine Naloxone, naltrexone... 

Naltrexone completely blocks the effects of IV opiates, as well as drugp with agonist-antagonist actions (butorphanol, nalbuphine, and pentazocine). The mechanism of action appears to be the same as that for naloxone... 

Naltrexone is used to treat persons dependent on opioids. Fhtients receiving naltrexone have been detoxified and are enrolled in a program for treatment of narcotic addiction. Naltrexone, along with other methods of treatment (counseling, psychotherapy), is used to maintain an opioid-free state Fhtients taking naltrexone on a... 

Administration of naltrexone may result in anxiety, dif-ficully sleeping, abdominal cramps, nasal congestion, joint and muscle pain, nausea, vomiting, dizziness, irritability, depression, fatigue, and drowsiness. 

Naltrexone is contraindicated in those with a hypersensitivity to the narcotic antagonists. Naltrexone is contraindicated during pregnancy (Category C). Naltrexone is used cautiously in those with a narcotic addiction in patients with cardiovascular disease, acute hepatitis, liver failure, or depression and in patients who are suicidal. Naltrexone is used cautiously during lactation. 

Naltrexone may produce withdrawal symptoms in those physically dependent on narcotics. The patient must not have taken any opiate for the last 7 to 10 days. Concurrent use of naltrexone with tiiioridazine may cause increased drowsiness and lethargy. Naltrexone may prevent the action of opioid antidiarrheals, antitus-sives, and analgesics. 

Educating the Patient and Famiiy The nurse instructs patients under treatment for narcotic addiction to wear or carry identification indicating that they are receiving naltrexone If the patient is taking naltrexone and requires hospitalization, it is important that all medical personnel be aware of therapy with this drug. Narcotics administered to these patients have no effect and therefore do not relieve pain. Fhtients receiving naltrexone may pose a problem if they experience acute pain. The primary health care provider must decide what methods must be used to control pain in these patients. 

The nurse should teach the patient taking naltrexone the impact of therapy. While taking the drug, any use of heroin or other opiate by the patient results in no effect. In fact, large doses of heroin or other opiates can overcome the drug s effect and result in coma or death. 

When given a narcotic analgesic for acute pain, a patient taking naltrexone for narcotic addiction... 

When naltrexone is administered with thioridazine, the nurse monitors the patient for... 

The physician prescribes naltrexone (ReVia) 25 mg PO initially. The nurse is to observe the patient carefully and if no withdrawal signs appear, 100 mg PO of the drug is prescribed every other day. On hand is naltrexone 50-mg tablets. The nurse administers as the initial dose. 

C4H5CIO 4023-34-1) see Buprenorphine Fexofenadine hydrochloride Naltrexone Prazepam cyclopropanecarboxylic acid ethyl ester (C(,H o02 4606-07-9) see Pimozide... 

C4H7Br 7051-34-5) see Betaxolol Ciraetropium bromide Flutoprazepam Naltrexone Prazepam A -cyclopropylmethyI-6,14-e do-ethano-7a-I(lS)-l-hy-droxy-1,2,2-trim ethylpropyijtetrahydronorthebaine (C30H43NO4 16524-65-5) sec Buprenorphine (2-cyc)opropyl-2-oxoethyl)triphenyIphusphomum bromide... 

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