Therapeutic drug monitoring
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Randomized Controlled Trial
Delta(9)-tetrahydrocannabinol, 11-hydroxy-delta(9)-tetrahydrocannabinol and 11-nor-9-carboxy-delta(9)-tetrahydrocannabinol in human plasma after controlled oral administration of cannabinoids.
A clinical study to investigate the pharmacokinetics and pharmacodynamics of oral tetrahydrocannabinol was performed. This randomized, double-blind, placebo-controlled, within-subject, inpatient study compared the effects of THC-containing hemp oils in liquid and capsule form to dronabinol (synthetic THC) in doses used for appetite stimulation. The National Institute on Drug Abuse Institutional Review Board approved the protocol and each participant provided informed consent. ⋯ Plasma THCCOOH persisted for at least 39.5 hours after the end of dosing and at much higher concentrations (up to 43.0 ng/mL). This study demonstrated that subjects who used high THC content hemp oil (347 mug/mL) as a dietary supplement had THC and metabolites in plasma in quantities comparable to those of patients using dronabinol for appetite stimulation. There was a significant correlation between body mass index and Cmax and body mass index and number of specimens positive for THC and 11-OH-THC.
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Randomized Controlled Trial
Estimating time of last oral ingestion of cannabis from plasma THC and THCCOOH concentrations.
Estimating the time of last cannabis use is important in assessing possible impairment of drivers involved in accidents, in verifying accuracy of court testimony and in the future, helpful in therapeutic monitoring of cannabis agonists. In 1992, Huestis et al developed model 1, based on plasma Delta-tetrahydrocannabinol (THC) concentrations, and model 2, on plasma 11-nor-9-carboxy-Delta(9)-tetrahydrocannbinol/THC ratios, that predicted 95% confidence intervals for time of last cannabis use. These models seemed to be valuable when applied to the small amount of data from published studies of oral ingestion, a route of administration more popular with the advent of cannabis therapies. ⋯ All plasma specimens with analyte concentrations >LOQ (n=90) were evaluated. Models 1 and 2 correctly predicted time of last THC ingestion for 74.4% and 90.0% of plasma specimens, respectively. 96.7% of predicted times were correct with one overestimate and 2 underestimates using the time interval defined by the lowest and highest 95% confidence limit of both models. These results provide further evidence of the usefulness of the predictive models in estimating the time of last oral THC ingestion after single or multiple doses.
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Seeds of nutmeg are used as spice, but they are also abused because of psychotropic effects described after ingestion of large doses. It was postulated that these effects could be attributable to metabolic formation of amphetamine derivatives from the main nutmeg ingredients elemicin (EL), myristicin (MY), and safrole (SA). In a case of a suspected nutmeg abuse, neither such amphetamine derivatives nor the main nutmeg ingredients could be detected in urine. ⋯ In the human urine sample, the following metabolites could be identified: O-demethyl elemicin, O-demethyl dihydroxy elemicin, demethylenyl myristicin, dihydroxy myristicin, and demethylenyl safrole. As in the human urine sample, neither amphetamine derivatives nor the main nutmeg ingredients could be detected in the rat urine samples. Finally, toxicologic detection of nutmeg abuse was possible by identification of the described metabolites of the EL, MY, and SA in urine applying the authors' systematic toxicologic analysis procedure using full-scan gas chromatography-mass spectrometry after acid hydrolysis, liquid-liquid extraction of analytes, and microwave-assisted acetylation of extracted analytes.
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Pharmacokinetics and pharmacodynamics of methadone enantiomers in hospice patients with cancer pain.
Racemic methadone is increasingly used to manage cancer pain. The authors studied 13 terminally ill patients with cancer pain, who underwent switching (rotation) from morphine to methadone. The relationship between initial morphine dose and final methadone dose, the pharmacokinetics of R- and S- methadone, and the degree of pain control and side effects were investigated. ⋯ The low and variable clearance values generally resulted in slow achievement of steady-state concentrations over several days; inappropriately high plasma methadone levels occurred in 1 patient. Whereas optimal pain control was achieved in 46% of patients, there was no relationship with plasma concentrations of methadone. Best practice for methadone use in this patient group should include monitoring of both pain and methadone concentration.
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Comparative Study Controlled Clinical Trial
Ketoconazole renders poor CYP3A phenotype status with midazolam as probe drug.
Drugs metabolized by cytochrome CYP3A isoenzymes have wide interindividual variability and normally distributed plasma clearance distributions. This makes precise dosing difficult to achieve clinically, which may compromise safe therapy. We hypothesized that with potent inhibition of CYP3A, we could clinically render patients "poor metabolizer" phenotype status, and thus reduce interindividual pharmacokinetic variability of midazolam, a well-known CYP3A substrate. ⋯ A limited sampling model consisting of time points at 15 and 300 minutes was validated as a phenotype for CYP3A activity to facilitate the use of midazolam as a probe drug for CYP3A activity. Potent inhibition of CYP3A by ketoconazole reduced midazolam CL and area-under-the-curve variability, allowing for more precise achievement of therapeutic target drug exposure. Prospective evaluation of this approach, together with dose adjustment based on limited sampling, seems warranted.