Narcotic blockade

Dole VP, Nyswander ME and Kreek MJ (1966). Narcotic blockade. Archives of International Medicine, 118, 304-309. 

Suppression of heroin self-administration in opioid-dependent volunteers has been found to be greater at doses over lOOmg (Donny et al. 2005), and this relates to the three-level effects of methadone, the implications of which we often have to contend with in our discussions with patients. Basically low doses of methadone will suppress opiate withdrawal symptoms in dependent individuals, and this is what a lot of patients mean when they say that their dose (which may be considered too low by us) holds them. In medium to high levels of methadone there is less craving for opiates, and then at the highest doses there will be full narcotic blockade (Donny et al. 2002), but as already indicated the users themselves may not wish to take such dosages. 

Dole VP, Nyswander ME, Kreek MJ (1966) Narcotic blockade-a medical technique for stopping heroin use by addicts. Trans Assoc Am Physicians 79 122-136... 

Narcotic addiction Blockade of the effects of exogenously administered opioids. A/co/ o//s/t . Treatment of alcohol dependence. 

Adults. 3 g PO q6h x 4 PRN Supl 1-2 g IM or IV repeat PRN Preeclampsia/pre-mature labor 4 g load then g/h IV inf Cardiac arrest 1-2 g IV push (2-4 mL 50% soln) in 10 mL DjW AMI Load 1-2 g in 50-100 mL D5W, over 5-60 min IV then 0.5-1.0 g/h IV up to 24 h (ECC 2005) Feds. 25-50 mg/kg/dose IM or IV q4-6h for 3-4 doses repeat PRN dose w/ low urine output or renal insuff Caution [B, +] Contra Heart block, renal failure Disp Inj 10, 20, 40, 80, 125, 500 mg/mL bulk powder SE CNS depression, D, flushing, heart block Interactions T CNS depression W/ antidepressants, antipsychotics, anxiolytics, barbiturates, hypnotics, narcotics EtOH T neuromuscular blockade Wf aminoglycosides, atracurium, gallamine, pancuronium, tubocurarine, vecuronium EMS Check for absent patellar reflexes this may indicate tox may cause hypokalemia (flattened T waves) and hypocalcemia OD May cause hypotension, resp arrest, T PR, QRS, and QT interval, AV block, and cardiac arrest calcium salts can be given to reverse resp depression... 

Combie J, Shults T, Nugent E C et al 1981 Pharmacology of narcotic analgesics in the horse selective blockade of narcotic-induced locomotor activity. American Journal of Veterinary Research 42 716-721... 

The subsequent introduction of naloxone s cyclopropylmethyl analog, naltrexone (Trexan, Fig. 5-9), with its ready oral absorption and considerably longer duration of action has made possible the use of a pure antagonist in the treatment of narcotic addicts. Naltrexone in once-a-day oral doses of 50 mg will produce satisfactory clinical blockade of intravenously administered opiates.10 In fact, a single dose of 100 or 150 mg can be used on a once, every other, or third-day basis. This drug may represent a small advance in the battle against opiate dependency. Naltrexone has been approved (1994) to obtund the cravings of alcohol abusers. 

Naltrexone, in a dose of 50 mg, will block the pharmacological effects of 25-mg heroin given intravenously for 24 hours, and the duration of blockade is dose-dependent. Naltrexone undergoes extensive first-pass metabolism, becoming converted to a 6-beta naltrexol, which is an active and pure narcotic-receptor antagonist and is excreted by the kidneys. Naltrexone can cause a dose-related hepatic injury. 

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