Reserpine excretion

Conversely, certain drugs modify the effectiveness or side effects of aspirin. Phenobarbital, occasionally used for seizures, induces liver enzymes that increase the metabolism and excretion of aspirin, (3-adrenoceptorblocking drugs, such as propranolol, and decrease the antiinflammatory effects of aspirin, whereas reserpine decreases its analgesic effects. Antacids decrease the absorption of aspirin. Alcohol consumption in combination with aspirin increases the latter s ulcerogenic effects. 

Reserpine is metabolised by the liver (3 2-3U) with more than 90% excreted as metabolites(33). The major urinary metabolites are methyl reserpate and 3,5-trimethoxy-benzoic acid. Other metabolites are shown in Scheme 3 (35). 

The principal advantage of a blood sample is ftiat its integrity is easier to safeguard because it is usually collected by a doctor or veterinary sm geon who is experienced in the procedure. In addition, drug concentrations in blood are more easily interpreted than those in urine, and certain chugs which are not excreted in urine in detectable quantities (e.g. reserpine) can be detected in blood. 

The amount of drug in plasma is unlikely to bear any consistent relationship to drug concentration at the site of action because of irreversible reserpine binding to storage vesicles. Reserpine is entirely metabolized, and none of the parent drug is excreted unchanged. 

Carlsson, A., Rasmussen, E. B. and Kristiansen, P., The urinary excretion of adrenaline and noradrenaline by schizophrenic patients during reserpine treatment, J. Neurochem. 4, 318 (1959). 

Reserpine, tritiated in the 2-and 6-positions of the trimethoxy-benzoyl ring, was administered orally to human subjects. The major urin u y metabolite was H-trimethoxybenzoic acid, while most of the radioactivity in the feces, the predominant route of excretion, was unaltered reserpine. ... 

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