Opiates excretion

Mechanism of Action An opioid agonist that binds at opiate receptor sites in central nervous system (CNS). Therapeutic Effect Reduced intensity of pain stimuli incoming from sensory nerve endings, alteringpain perception and emotional response to pain. Pharmacokinetics Rapidly absorbed. Protein binding 40%-50%. Extensively distributed. Metabolized in liver. Excreted in urine. Half-life 11 hr. 

Distribution, Metabolism, and Excretion Mechanisms of Opiate Action Discovery of Endorphins What Do Endorphins Do ... 

Most opiate drugs arc rapidly metabolized in the liver and excreted by the kidneys. Excretion of opiates is fairly rapid, with 90% excretion within a day after taking the drug. Hov e cr, traces of morphine may remain in urine for two to four days after use (Hawks C hiang, 1986). 

Cone EJ, Welch P, Paul BD, Mitchell JM. Forensic drug testing for opiates III. Urinary excretion rates of morphine and codeine following codeine administration. J Anal Toxicol 1991 15 161-6. 

The opioids mentioned above are mainly excreted renally (via the kidneys). The proportion excreted in the bile (via the gall bladder) always lies approximately between 10 and 20%. Figure 8-14 shows the important steps in the metabolism of some opiates. 

Some apparent analytical inconsistencies may provide important forensic information. For example, if a result for opiates is negative in urine, but positive in blood, it is quite likely that heroin was administered shortly before death and the metabolites had not yet been excreted. This situation is often found in acute sudden death among heroin users in whom substantial urinary excretion has not yet occurred. 

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