Heroin brain, effects

Opioids are easily absorbed subcutaneously and intramuscularly, as well as from the gastrointestinal tract, nasal mucosa (e.g., when heroin is used as snuff), and lung (e.g., when opium is smoked). About 90% of the excretion of morphine occurs during the first 24 hours, but traces are detectable in urine for more than 48 hours. Heroin (diacetyhnorphine) is hydrolyzed to monoacetylmorphine, which is then hydrolyzed to morphine. Morphine and monoacetylmorphine are responsible for the pharmacologic effects of heroin. Heroin produces effects more rapidly than morphine because it is more lipid soluble and therefore crosses the blood-brain barrier faster. In the urine, heroin is detected as free morphine and morphine glucuronide (Gutstein and Akil 2001 Jaffe et al. 2004). 

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. 

Agonist drugs can also bind directly to the postsynaptic receptor, so mimicking the physiological effect of the neurotransmitter for example, morphine and heroin bind to the brain s opiate receptors and, thus, directly stimulate feelings of pleasure and pain... 

Designer drugs, as well as other drugs like alcohol, cocaine, and heroin, produce their effects on the brain by altering the... 

Gerrits MA, Van Ree JM (1996) Effect of nucleus accumbens dopamine depletion on motivational aspects involved in initiation of cocaine and heroin self-administration in rats. Brain Res 713 114-124... 

In October 2002, the FDA approved two new medications for treating opiate addiction, both developed by Reckitt Benckiser Pharmaceuticals. The new drugs, Subutex (buprenorphine hydrochloride) and Suboxone tablets (buprenorphine hydrochloride and naloxone hydrochloride) contain buprenorphine, a partial opioid agonist. Like methadone, buprenorphine binds to the brain s opioid receptors, but produces significantly reduced pleasurable effects than heroin. 

The proposal that the effects of heroin are mediated chiefly by its deacetylated metabolites, morphine and 6-monoacetylmorphine (MAM) [28], and that heroin (and MAM) function primarily as carriers to facilitate morphine availability at C.N.S. receptor sites is supported by studies in new-born rats [29]. While rats show a pronounced increase in their resistance to morphine 16 days afterbirth (probably associated with development of a blood-brain barrier), there is little change in toxicity to heroin with increasing age hence ready access of heroin to the brain is concluded, even after the barrier has developed. 

In opiate abuse, smack ( junk, jazz, stuff, China white mostly heroin) is self administered by injection ( mainUning ) so as to avoid first-pass metabolism and to achieve a faster rise in brain concentration. Evidently, psychic effects ( kick, buzz, rush ) are especially intense with this route of administration. The user may also resort to other more unusual routes opium can be smoked, and heroin can be taken as snuff (B). 

Pharmacokinetics plays a very important role in the manner in which opioids are abused. Morphine and many of its derivatives are slowly and erratically absorbed after oral administration, which makes this route suitable for long-term management of pain but not for producing euphoria. In addition, opioids undergo considerable first-pass metabolism, which accounts for their low potency after oral administration. Heroin is more potent than morphine, although its effects arise primarily from metabolism to morphine. The potency difference is attributed to heroin s greater membrane permeability and resultant increased absorption into the brain. 

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