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Background: Genetic polymorphisms play an important role in the response to a drug regimen, based on the metabolic rate, which determines the interindividual variability. Quantitative differences in the cytochrome P450 expression, specially CYP2D6, can be assayed by means of a drug metabolism such as that of dextromethorphan. Aim: To characterize the oxidative phenotype of a pediatric population in Tlaltizapan, Morelos, using dextromethorphan as a metabolic probe. Materials and methods: This prospective, transversal, descriptive and experimental study was performed in a Mexican Rural Research Centre, located in Tlaltizapan, Morelos, a dependence of the National Institute of Pediatrics. It includes the phenotyping of a healthy pediatric population by evaluating their urinary excretion of dextromethorphan and its metabolites. Results: Five children (29%) of the 17-subject population evaluated, were slow metabolizers, while the remaining 12 children (71%) were non-slow or fast metabolizers. Conclusion: Clinically the type of metabolism within a population, whether slow or fast, indicates that individuals in both extremes of the histogram are in high risk of having adverse reactions to drugs, or poor developing or failed therapeutic response receiving when CYP2D6-metabolized drugs. [ABSTRACT FROM AUTHOR]

Background: The lack of pediatric drug formulations is a problem that has limited the prescription in that population in the long term, resulting errors in drug administration by patients. Objetive: To determine the frequency of drug consumption at a National Pediatrics Institute in a six year-period, and identify those medications for which there is no available pediatric formulation. Methods: The frequency of consumption of medications was investigated, using the data base at the Pharmacy of the National Pediatrics Institute during the period from January 2001 to June 2006. Drugs were grouped according to their frequency, identifying those not available for pediatric use which are nevertheless prescribed. Results:. About 85 different drugs were used to attend hospital demands, which were prescribed on 7514 occasions within the period of study. The most frequently used drugs were: ranitidine (4.7%), paracetamol (3.8%) and midazolam (3.7%). Our results showed that midazolam, furosemide, phenobarbital, omeprazole, prednisone and captopril were the most prescribed drugs for which there are no pediatric formulations commercially available. Conclusion: This article reports the frequency of drug consumption at a pediatric hospital and discusses it in view of the lack of adequate formulations for pediatric patients in our country. [ABSTRACT FROM AUTHOR]

Metabolic polymorphism can alter the efficiency of a treatment or influence the occurrence of adverse reactions. Cytochrome 450, includes CYP2D6 which metabolizes 20% of drugs such as antipsychotic and antidepressive. Several studies have shown significant racial differences in the prevalence of phenotypes of CYP2D6, but there is not enough information on this subject in pediatric populations. Polymorphism of cytochrome is of great importance in pediatric pharmacotherapy, because of its therapeutic limitations are due to the lack of knowledge of metabolic characterization as well as, the lack of monitoring of the treatment results. Pharmacogenetic techniques are important inasmuch as they help physicians to prescribe more adequate doses of antipsychotic drugs which are currently effective only in 30% of the patients. "Personalized medicine" is important in psychiatry in order to optimize the dose of psychoactive drugs, by means of the use of CYP2D6 phenotyping, which allows to classify patients as slow, fast, intermediate and ultrarapid metabolizers. Phenotyping is done with the use of dextromethorphan as an indicator of the metabolism of CYP2D6. After oral administration of a single 0.5 mg/kg dose of DM, its urinary concentration and that of its metabolite (dextrorphan) are measured with HPLC method for fluorescence detection. [ABSTRACT FROM AUTHOR]