Heroin positive effects

Toluene, volatile nitrites, and anesthetics, like other substances of abuse such as cocaine, nicotine, and heroin, are characterized by rapid absorption, rapid entry into the brain, high bioavailability, a short half-life, and a rapid rate of metabolism and clearance (Gerasimov et al. 2002 Pontieri et al. 1996, 1998). Because these pharmacokinetic parameters are associated with the ability of addictive substances to induce positive reinforcing effects, it appears that the pharmacokinetic features of inhalants contribute to their high abuse liability among susceptible individuals. 

Besides being affected by medications and substances that affect the liver s metabolism, methadone itself affects the liver s metabolism of certain substances. A significant number of people who are taking methadone for heroin addiction also are HIV positive and are taking anti-HIV medications such as Desipramine (DMI) and zidovudine (AZT). Through its actions on the liver, methadone decreases the metabolism of these medications. Because of this, certain troublesome side effects of DMI and AZT, including nausea,... 

The effects of heroin on the CNS are related to 6-monoacetylmorphine (6-MAM) and mainly morphine. The heroin crosses the blood-brain barrier due to the acetylic groups in position 3 and 6, that increase its lipophilicity. The morphinic compounds interact with the opioid receptors, mainly the p receptors, acting as an antagonist by mimicking the endorphin effects [9], Usually the first event occurs 30 s after its administration with a typical rush followed by a succession of euphoric sensations after a few minutes the user becomes calm, satisfied, and indifferent to his surroundings after 2-4 h typical restlessness accompanied with pain and an incessant demand for heroin sets in the craving. 

Enkephalins could be implicated in dopamine mesoaccumbens-depen-dent appetitive motivation and behavioral positive reinforcement by separated mechanisms involving both mu and delta receptors. Activation of the former in heroin abusers produces sedation and overstimulation, lack of vigilance, and possibly fear. These effects cannot be reached with dual inhibitors, and one can speculate that this is related to an increased level of endogenous enkephalins leading to a preferential interaction with delta receptors for both binding and anatomical reasons. 

The predominant effects of serotonin are inhibitory. It enhances the action of the GABA, the major inhibitory neurotransmitter. Serotonin has an excitatory effect by increasing the release of dopamine, a neurotransmitter involved in love, sex, and feelings of well being. Reduction in serotonin activity makes people incapable of experiencing normal positive rewards. Dopamine activity is enhanced by alcohol, cocaine, amphetamine, heroin, and risk-taking behavior. 

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