Pitfalls and challenges associated with phenoconversion in forensic toxcicology.

PURPOSE: In recent years, several publications have demonstrated the interest and the usefulness of pharmacogenetics in forensic toxicology. However, this approach remains namely focused on DNA-based phenotype, which may potentially lead to misinterpretation. Other determinants such as co-medication or physiological parameters may also impact the phenotype. This article aims to highlight the importance of considering such determinants in forensic toxicology, through the original case of a heroin-related fatality. METHOD: Ethanol concentration determination and toxicological screening were performed using gas chromatography with flame ionization detection, liquid chromatography with diode array detection and gas chromatography with mass spectrometry detection. CYP2C19 and CYP2D6 genotypes were determined by Taqman® real-time PCR analyses. RESULTS: Femoral blood analyses revealed the presence of ethanol, morphine, codeine, venlafaxine (VEN), O-desmethylvenlafaxine (ODV) and N-desmethylvenlafaxine (NDV), paroxetine, and risperidone. 6-acetylmorphine was also identified in urine. VEN, paroxetine and risperidone were quantified at supra-therapeutic or toxic blood concentrations. NDV was not quantified. The metabolic ratio of VEN (ODV to VEN) was exceptionally low (about 0.7). Pharmacogenetics testing showed that the patient was heterozygous for the CYP2C19*2 loss-of-function allele, which predict an intermediate metabolism for CYP2C19. None of the deficient CYP2D6 alleles investigated were identified. Those results suggest an extensive CYP2D6-metabolism phenotype. CONCLUSION: A discrepancy was seen between the results of the genomic evaluation and the observed metabolic ratio of VEN. This tends to exclude a genetic origin and lead us to formulate other hypotheses, such as phenoconversion that may have been induced by drug interaction involving patients' regular medications. Phenoconversion is as a complex phenomenon that leads to genotype-phenotype mismatch without any genetic abnormality particularly described for cytochromes P450 2D6 and 2C19. Although transient, phenoconversion can have a significant impact on the analysis and interpretation of genotype-focused clinical outcomes correlation and in forensic toxicology conclusions.

Chronic treatment with a tryptophan-rich protein hydrolysate improves emotional processing, mental energy levels and reaction time in middle-aged women.

Common pharmacological treatments of mood disorders aim to modulate serotonergic neurotransmission and enhance serotonin levels in the brain. Brain serotonin levels are dependent on the availability of its food-derived precursor essential amino acid tryptophan (Trp). We tested the hypothesis that delivery of Trp via food may serve as an alternative treatment, and examined the effects of a Trp-rich, bioavailable dietary supplement from egg protein hydrolysate on cognitive and emotional functions, mood state, and sleep quality. In a randomised, placebo-controlled, parallel trial, fifty-nine mentally and physically healthy women aged 45-65 years received placebo (n 30) or the supplement (n 29) (both as 0.5 g twice per d) for 19 d. Emotional processing was significantly changed by supplementation, exhibiting a shift in bias away from negative stimuli. The results for the Affective Go/No-Go Task exhibited a slowing of responses to negative words, suggesting reduced attention to negative emotional stimuli. The results for the Facial Emotional Expression Rating Task also supported a shift away from attention to negative emotions and a bias towards happiness. An increase in arousal-like symptoms, labelled 'high energy', shorter reaction times and a slight benefit to sustained attention were observed in the treated subjects. Finally, when the supplement was taken 60-90 min before bedtime, a feeling of happiness before going to bed was consistently reported. In summary, daily consumption of a low-dose supplement containing bioavailable Trp may have beneficial effects on emotional and cognitive functions.

Food-derived serotonergic modulators: effects on mood and cognition.

The most frequently described drugs in the treatment of mood disorders are selective serotonin reuptake and monoamine oxidase (MAO) inhibitors, enhancing serotonin levels in the brain. However, side-effects have been reported for these drugs. Because serotonin levels in the brain are dependent on the availability of the food-derived precursor tryptophan, foods such as chicken, soyabeans, cereals, tuna, nuts and bananas may serve as an alternative to improve mood and cognition. Here we discuss the effects of high- or low-tryptophan-containing food, as well as plant extracts with a modest monoamine reuptake and MAO-A inhibition functional profile, on mood and cognition in healthy and vulnerable human subjects and rodents. Together the studies suggest that there is an inverted U-shaped curve for plasma tryptophan levels, with low and too high tryptophan levels impairing cognition, and moderate to high tryptophan levels improving cognition. This relationship is found for both healthy and vulnerable subjects. Whereas this relationship may also exist for mood, the inverted U-shaped curve for plasma tryptophan levels and mood may be based on different tryptophan concentrations in healthy v. vulnerable individuals. Animal studies are emerging and allow further understanding of effects and the mode of action of food-derived serotonergic components on mood, cognition and mechanisms. Ultimately, insight into the concentrations of tryptophan and other serotonergic components in food having beneficial effects on mood and cognition in healthy, but particularly vulnerable, subjects may support well-being in our highly demanding society.

4-Methyl-amphetamine: a health threat for recreational amphetamine users.

4-Methylamphetamine (4-MA) was originally developed as an appetite suppressant, but development was halted due to side effects. It has recently resurfaced as a new psychoactive substance in Europe, and is mostly found together with amphetamine. Around 11.5% of tested Dutch speed samples were positive for 4-MA. In Belgium, 4-MA was also found in speed samples. In 2011 and 2012, several fatal incidents after amphetamine use were observed in Belgium, the United Kingdom and The Netherlands. In all victims, toxicological analysis confirmed the presence of 4-MA, in addition to amphetamine. The observed blood amphetamine levels were too low to be fatal. Contrary to amphetamine, which displays noradrenergic and dopaminergic activity, 4-MA also shows serotonergic activity, which may contribute to the observed toxicity. Other mechanisms of toxicity are put forward in this paper as well. To conclude, the observed toxicity is most likely the result of the combined dopaminergic activity of amphetamine and the serotonergic activity of 4-MA. In addition, the presence of 4-MA may have dampened the psychoactive effects of amphetamine by attenuation of the amphetamine-induced dopamine release, potentially inclining users to ingest higher doses of contaminated speed. Also, slower metabolism of 4-MA and its MAO-inhibiting properties can also contribute to the unusual high toxicity of 4-MA.

Single oral doses of (±) 3,4-methylenedioxymethamphetamine ('Ecstasy') produce lasting serotonergic deficits in non-human primates: relationship to plasma drug and metabolite concentrations.

Repeated doses of the popular recreational drug methylenedioxymethamphetamine (MDMA, 'Ecstasy') are known to produce neurotoxic effects on brain serotonin (5-HT) neurons but it is widely believed that typical single oral doses of MDMA are free of neurotoxic risk. Experimental and therapeutic trials with MDMA in humans are underway. The mechanisms by which MDMA produces neurotoxic effects are not understood but drug metabolites have been implicated. The aim of the present study was to assess the neurotoxic potential of a range of clinically relevant single oral doses of MDMA in a non-human primate species that metabolizes MDMA in a manner similar to humans, the squirrel monkey. A secondary objective was to explore the relationship between plasma MDMA and metabolite concentrations and lasting serotonergic deficits. Single oral doses of MDMA produced lasting dose-related serotonergic neurochemical deficits in the brains of squirrel monkeys. Notably, even the lowest dose of MDMA tested (5.7 mg/kg, estimated to be equivalent to 1.6 mg/kg in humans) produced significant effects in some brain regions. Plasma levels of MDMA engendered by neurotoxic doses of MDMA were on the order of those found in humans. Serotonergic neurochemical markers were inversely correlated with plasma concentrations of MDMA, but not with those of its major metabolites, 3,4-dihydroxymethamphetamine and 4-hydroxy-3-methoxymethamphetamine. These results suggest that single oral doses of MDMA in the range of those used by humans pose a neurotoxic risk and implicate the parent compound (MDMA), rather than one of its metabolites, in MDMA-induced 5-HT neural injury.

Clinical pharmacology of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy"): the influence of gender and genetics (CYP2D6, COMT, 5-HTT).

UNLABELLED: The synthetic psychostimulant MDMA (± 3,4-methylenedioxymethamphetamine, ecstasy) acts as an indirect serotonin, dopamine, and norepinephrine agonist and as a mechanism-based inhibitor of the cytochrome P-450 2D6 (CYP2D6). It has been suggested that women are more sensitive to MDMA effects than men but no clinical experimental studies have satisfactorily evaluated the factors contributing to such observations. There are no studies evaluating the influence of genetic polymorphism on the pharmacokinetics (CYP2D6; catechol-O-methyltransferase, COMT) and pharmacological effects of MDMA (serotonin transporter, 5-HTT; COMT). This clinical study was designed to evaluate the pharmacokinetics and physiological and subjective effects of MDMA considering gender and the genetic polymorphisms of CYP2D6, COMT, and 5-HTT. A total of 27 (12 women) healthy, recreational users of ecstasy were included (all extensive metabolizers for CYP2D6). A single oral weight-adjusted dose of MDMA was administered (1.4 mg/kg, range 75-100 mg) which was similar to recreational doses. None of the women were taking oral contraceptives and the experimental session was performed during the early follicular phase of their menstrual cycle. Principal findings show that subjects reached similar MDMA plasma concentrations, and experienced similar positive effects, irrespective of gender or CYP2D6 (not taking into consideration poor or ultra-rapid metabolizers) or COMT genotypes. However, HMMA plasma concentrations were linked to CYP2D6 genotype (higher with two functional alleles). Female subjects displayed more intense physiological (heart rate, and oral temperature) and negative effects (dizziness, sedation, depression, and psychotic symptoms). Genotypes of COMT val158met or 5-HTTLPR with high functionality (val/val or l/*) determined greater cardiovascular effects, and with low functionality (met/* or s/s) negative subjective effects (dizziness, anxiety, sedation). In conclusion, the contribution of MDMA pharmacokinetics following 1.4 mg/kg MDMA to the gender differences observed in drug effects appears to be negligible or even null. In contrast, 5-HTTLPR and COMT val158met genotypes play a major role. TRIAL REGISTRATION: ClinicalTrials.gov NCT01447472.

The neuropharmacology of prolactin secretion elicited by 3,4-methylenedioxymethamphetamine ("ecstasy"): a concurrent microdialysis and plasma analysis study.

3,4-methylenedioxymethamphetamine (MDMA) is a substituted phenethylamine that is widely abused as the street drug "ecstasy". Racemic MDMA (S,R(+/-)-MDMA) and its stereoisomers elicit complex spectrums of psychobiological, neurochemical, and hormonal effects. In this regard, recent findings demonstrated that S,R(+/-)-MDMA and its stereoisomer R(-)-MDMA elicit increases in striatal extracellular serotonin levels and plasma levels of the hormone prolactin in rhesus monkeys. In the present mechanistic study, we evaluated the role of the serotonin transporter and the 5-HT(2A) receptor in S,R(+/-)-MDMA- and R(-)-MDMA-elicited prolactin secretion in rhesus monkeys through concurrent microdialysis and plasma analysis determinations and drug interaction experiments. Concurrent neurochemical and hormone determinations showed a strong positive temporal correlation between serotonin release and prolactin secretion. Consistent with their distinct mechanisms of action and previous studies showing that the serotonin transporter inhibitor fluoxetine attenuates the behavioral and neurochemical effects of S,R(+/-)-MDMA, pretreatment with fluoxetine attenuated serotonin release elicited by either S,R(+/-)-MDMA or R(-)-MDMA. As hypothesized, at a dose that had no significant effects on circulating prolactin levels when administered alone, fluoxetine also attenuated prolactin secretion elicited by S,R(+/-)-MDMA. In contrast, combined pretreatment with both fluoxetine and the selective 5-HT(2A) receptor antagonist M100907 was required to attenuate prolactin secretion elicited by R(-)-MDMA, suggesting that this stereoisomer of S,R(+/-)-MDMA elicits prolactin secretion through both serotonin release and direct agonism of 5-HT(2A) receptors. Accordingly, these findings inform our understanding of the neuropharmacology of both S,R(+/-)-MDMA and R(-)-MDMA and the regulation of prolactin secretion.

Deaths involving MDMA and the concomitant use of pharmaceutical drugs.

The increasing use of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") and tendency of users to combine MDMA with pharmaceutical agents (especially serotonergic medication) warrants a thorough understanding of MDMA's toxicity profile and potential for drug interactions. This study examined the involvement of MDMA and concurrently administered pharmaceutical drugs in cases reported to the Victorian State Coroner. The National Coroners Information System was used to conduct a comprehensive search and examination of all closed cases between 2002 and 2008 where MDMA was detected. Pathology, toxicology, and Coroners' findings were considered in all cases. In all, 106 fatalities were identified, of which 43 (41%) cases involved the concomitant use of MDMA with other drugs, including pharmaceuticals that were likely to result in an adverse drug reaction or varying risks (4 high-risk cases involved moclobemide and MDMA, in addition to 10 moderate-risk cases, and 5 minor-risk cases). These findings highlight the importance of recognizing and publicizing potential drug interactions between MDMA and pharmaceutical preparations that may result in lethal toxicity, in particular serotonin toxicity.

Deaths involving serotonergic drugs.

Serotonin-active drugs are detected relatively frequently in Victorian deaths. During 2002-2008, there were 1123 fatalities where one or more of the serotonin-active drugs tramadol, venlafaxine, fluoxetine, sertraline, citalopram, paroxetine and MDMA, were detected. These deaths were reviewed using pathology, toxicology and police reports, to determine the contribution of these drugs to the cause of death, particularly if serotonin toxicity was the mechanism of death. There were 28 cases of most interest to this research because of the presence of the target drugs and the circumstances suggesting the likelihood of serotonin toxicity involvement in death. There were 5 cases of reported serotonin toxicity and 23 other deaths suspected to have involved this form of toxicity. Tramadol featured most commonly out of the seven target drugs and was frequently detected in combination with serotonergic antidepressants. MDMA was also detected relatively commonly and was associated with moclobemide in 4 cases of confirmed serotonin toxicity. There were an additional 1095 cases where natural disease, external injury or the misuse of other drugs caused death, of which 2 reported the incidental contribution of serotonin toxicity.

Ambient temperature effects on 3,4-methylenedioxymethamphetamine-induced thermodysregulation and pharmacokinetics in male monkeys.

Changes in ambient temperature are known to alter both the hyperthermic and the serotonergic consequences of 3,4-methylenedioxymethamphetamine (MDMA). Metabolism of MDMA has been suggested to be a requisite for these neurotoxic effects, whereas the hyperthermic response is an important contributing variable. The aim of the present study was to investigate the interaction between ambient temperature, MDMA-induced thermodysregulation, and its metabolic disposition in monkeys. MDMA (1.5 mg/kg i.v.) was administered noncontingently at cool (18 degrees C; n = 5), room (24 degrees C; n = 7), and warm (31 degrees C; n = 7) ambient temperatures. For 240 min following MDMA administration, core temperature was recorded and blood samples were collected for analysis of MDMA and its metabolites 3,4-dihydroxymethamphetamine (HHMA), 3,4-dihydroxyamphetamine, and 3,4-methylenedioxyamphetamine (MDA). A dose of 1.5 mg/kg MDMA induced a hypothermic response at 18 degrees C, a hyperthermic response at 31 degrees C, and did not significantly change core temperature at 24 degrees C. Regardless of ambient temperature, plasma MDMA concentrations reached maximum within 5 min, and HHMA was a major metabolite. Curiously, the approximate elimination half-life (t(1/2)) of MDMA at 18 degrees C (136 min) and 31 degrees C (144 min) was increased compared with 24 degrees C (90 min) and is most likely because of volume of distribution changes induced by core temperature alterations. At 18 degrees C, there was a significantly higher MDA area under the concentration-time curve (AUC) and a trend for a lower HHMA AUC compared with 24 degrees C and 31 degrees C, suggesting that MDMA disposition was altered. Overall, induction of hypothermia in a cool environment by MDMA may alter its disposition. These results could have implications for MDMA-induced serotonergic consequences.

Elevated childhood serotonergic function protects against adolescent aggression in disruptive boys.

OBJECTIVE: This longitudinal study examined whether responsiveness of the neurotransmitter serotonin (5-HT) in childhood predicts adolescent aggression. METHOD: Boys (N = 33) with disruptive behavior disorders who received assessments of central 5-HT function via the prolactin response to fenfluramine between 1990 and 1994 when they were 7 to 11 years old were re-evaluated clinically on average 6.7 years later. RESULTS: After accounting for baseline aggression, early 5-HT function accounted for a significant proportion of variance in adolescent aggression. This prospective relationship of childhood 5-HT function with adolescent aggression (r = -0.71) and antisocial behavior (r = -0.59) was found primarily in adolescents who were aggressive during childhood. Irrespective of childhood aggression, no child with high 5-HT function was particularly aggressive at follow-up. CONCLUSIONS: Low childhood 5-HT function appears important, but not sufficient, for the emergence of adolescent aggression. However, early high 5-HT function may protect against adolescent violence and aggression.

Fast onset medications through thermally generated aerosols.

Smoking involves heating a drug to form a mixture of drug vapor and gaseous degradation products. These gases subsequently cool and condense into aerosol particles that are inhaled. Here, we demonstrate rapid and reliable systemic delivery of pure pharmaceutical compounds without degradation products through a related process that also involves inhalation of thermally generated aerosol. Drug is coated as a thin film on a metallic substrate and vaporized by heating the metal. The thin nature of the drug coating minimizes the length of time during which the drug is exposed to elevated temperatures, thereby preventing its thermal decomposition. The vaporized, gas-phase drug rapidly condenses and coagulates into micrometer-sized aerosol particles. For the commonly prescribed antimigraine drug rizatriptan, inhalation of these particles results in nearly instantaneous systemic drug action.

Moclobemide poisoning: toxicokinetics and occurrence of serotonin toxicity.

AIMS: To investigate the spectrum of toxicity of moclobemide overdose, the occurrence of serotonin toxicity, and to estimate toxicokinetic parameters. METHODS: All moclobemide overdoses presenting over a 10-year period to the Hunter Area Toxicology Service were reviewed. Clinical features, complications, length of stay (LOS) and intensive care (ICU) admission rate were extracted from a standardized, prospectively collected database. Comparisons were made between moclobemide alone and moclobemide with a serotonergic coingestant poisoning. Serotonin toxicity was defined by a combination of Sternbach's criteria and a clinical toxicologist's diagnosis. In five patients serial moclobemide concentrations were measured. Time to maximal plasma concentration (Tmax), peak plasma concentration (Cmax) and terminal elimination half-lives were estimated. RESULTS: Of 106 included patients, 33 ingested moclobemide alone, 21 ingested moclobemide with another serotonergic agent (in some cases in therapeutic doses) and 52 ingested moclobemide with a nonserotonergic agent. Eleven (55%) of 21 patients coingesting a serotonergic drug developed serotonin toxicity, which was significantly more than one (3%) of 33 moclobemide-alone overdoses (odds ratio 35, 95% confidence interval 4, 307; P < 0.0001). In six of these 21 cases severe serotonin toxicity developed with temperature >38.5 degrees C and muscle rigidity requiring intubation and paralysis. The 21 patients had a significantly increased LOS (34 h) compared with moclobemide alone overdoses (12 h) (P < 0.0001) and a significantly increased ICU admission rate of 57% vs. 3% (P < 0.0001). Time to peak plasma concentration was delayed in two patients where prepeak samples were obtained. Cmax increased slightly with dose, but all three patients ingesting > or = 6 g vomited or had charcoal. The mean elimination half-life of moclobemide in the five patients in whom serial moclobemide concentrations were measured was 6.3 h and elimination was first order in all cases. There was no evidence of a dose-dependent increase in half-life. CONCLUSIONS: The effects of moclobemide alone in overdose are minor, even with massive ingestions. However, moclobemide overdose in combination with a serotonergic agent (even in normal therapeutic doses) can cause severe serotonin toxicity. The elimination half-life is prolonged by two to four times in overdose, compared with that found in healthy volunteers given therapeutic doses. This may be a result of wide interindividual variation in overall elimination, also seen with therapeutic doses, but appears not to be due to saturation of normal elimination pathways.

Death following ingestion of MDMA (ecstasy) and moclobemide.

Four deaths following the ingestion of moclobemide and MDMA ('ecstasy') are described. The probable cause of death in each case was serotonin syndrome as a result of an interaction between the two drugs. As none of the victims had been prescribed moclobemide it seems that each had taken the drug to enhance the effects of MDMA, with fatal consequences. Warnings are needed against misinformed attempts to potentiate the pharmacological effects of illicit drugs.

LC-MS analysis of serotonergic drugs.

Separating drugs which are both polar and basic has long been difficult because of the limited operating pH range of conventional HPLC columns. This paper describes a liquid chromatographic method capable of being used with either diode-array or mass spectrometric detection for the identification and quantitation of 10 antidepressant and 2 antipsychotic drugs, all of which have serotonergic activity. In developing the method, the effects of varying buffers and mobile phase pH and of adding modifying agents on resolution and capacity factors were investigated. The organic buffers ammonia, glycine, and triethylamine were each used in a mobile phase made up of 32.5% buffer/67.5% methanol (v/v) at a pH of 10.0. Additionally, four different concentrations each of tetrahydrofuran and acetonitrile were added to investigate the effect of a modifying agent on resolution and retention. In general, decreasing mobile phase pH reduced retention times and decreased resolution. Adding tetrahydrofuran in place of the same amount of methanol tended to decrease retention times, and adding acetonitrile tended to slightly increase retention times. However, addition of both marginally improved resolution. This method has been used to satisfactorily analyze brain, blood, liver, urine, vitreous fluid, and stomach contents in subjects known to have used these drugs.

Enantioselective metabolism of the designer drugs 3,4-methylenedioxymethamphetamine ('ecstasy') and 3,4-methylenedioxyethylamphetamine ('eve') isomers in rat brain and blood.

The metabolism of MDA (3,4-methylenedioxyamphetamine), HMMA (3-hydroxy-4-methoxymethylamphetamine) and HME (3-hydroxy-4-methoxyethylamphetamin) of the popular designer drugs MDMA ('ecstasy', 3,4-methylenedioxymethamphetamine) and MDE ('eve', 3,4-methylenedioxyethylamphetamine) was determined in rat serum, whole blood and urine, as well as in whole brain structures (cortex and striatum) after subcutaneous administration of 20 mg/kg MDMA and MDE, respectively. MDMA and MDE were extracted from serum and homogenized brain structures using a solid-phase extraction procedure. The extracts were examined by a validated high-performance liquid chromatography procedure coupled with fluorimetric detection. Our results demonstrate that MDMA is metabolized to a higher degree than MDE, resulting in a higher concentration of neurotoxic dihydroxymetabolites and (S)-MDA. There was no difference between the metabolism of MDMA and MDE and its respective isomers. Different concentrations of the respective isomers of MDMA and MDE let us suggest an enantioselective metabolism for both MDMA and MDE.

Neuroendocrine abnormalities in recreational ecstasy (MDMA) users: is it ecstasy or cannabis?

BACKGROUND: The purpose of this study was to investigate neuroendocrine function in ecstasy (3,4-methylenedioxymethamphetamine = MDMA) users and controls. METHODS: Prolactin response to d-fenfluramine was assessed in abstinent ecstasy users with concomitant use of cannabis only (n = 24, male/female 13/11) and in two control groups: healthy nonusers (n = 13, female) and exclusive cannabis users (n = 7, male). RESULTS: Prolactin response to d-fenfluramine was slightly blunted in female ecstasy users. Both male user samples exhibited a weak prolactin response to d-fenfluramine, but this was weaker in the group of cannabis users. Baseline prolactin and prolactin response to d-fenfluramine were associated with the extent of previous cannabis use. CONCLUSIONS: Endocrinological abnormalities of ecstasy users may be closely related to their coincident cannabis use. Cannabis use may be an important confound in endocrinological studies of ecstasy users and should be looked for more systematically in future studies.

Liquid chromatographic method with electrochemical detection for determination of cisapride in serum.

A sensitive liquid chromatographic (LC) method using electrochemical detection was developed for the identification and quantitation of cisapride in serum. The serum samples were deproteinized by a simple acetonitrile precipitation technique followed by n-hexane extraction. Cisapride in the deproteinized serum was separated by an isocratic elution with an ODS Hypersil LC column (150 x 4.6 mm) using a mobile phase consisting of 0.05M Na2HPO4-acetonitrile (60 + 40), pH 8.4. Cisapride eluted from the column was detected by a Coulochem II electrochemical detector. The precision of this assay method was determined by intra- and inter-day analyses of cisapride-free fetal bovine serum samples that were spiked with 25, 50, and 100 ng/mL cisapride. For the intra-day assay, recoveries were 94.3 +/- 1.4, 90.1 +/- 2.9, and 103.2 +/- 9.2%, respectively. This electrochemical detection LC method could be very useful in monitoring plasma levels of cisapride.