Ethnic differences in drug disposition and responsiveness

Genetic diversity of variants involved in drug response among Tunisian and Italian populations toward personalized medicine

Adverse drug reactions (ADR) represent a significant contributor to morbidity and mortality, imposing a substantial financial burden. Genetic ancestry plays a crucial role in drug response. The aim of this study is to characterize the genetic variability of selected pharmacogenes involved with ADR in Tunisians and Italians, with a comparative analysis against global populations. A cohort of 135 healthy Tunisians and 737 Italians were genotyped using a SNP array. Variants located in 25 Very Important Pharmacogenes implicated in ADR were extracted from the genotyping data. Distribution analysis of common variants in Tunisian and Italian populations in comparison to 24 publicly available worldwide populations was performed using PLINK and R software. Results from Principle Component and ADMIXTURE analyses showed a high genetic similarity among Mediterranean populations, distinguishing them from Sub-Saharan African and Asian populations. The Fst comparative analysis identified 27 variants exhibiting significant differentiation between the studied populations. Among these variants, four SNPs rs622342, rs3846662, rs7294, rs5215 located in SLC22A1, HMGCR, VKORC1 and KCNJ11 genes respectively, are reported to be associated with ethnic variability in drug responses. In conclusion, correlating the frequencies of genotype risk variants with their associated ADRs would enhance drug outcomes and the implementation of personalized medicine in the studied populations.

β1-adrenergic receptor polymorphisms: a possible genetic predictor of bisoprolol response in acute coronary syndrome

Aim

To investigate the association between beta1-adrenergic receptor (ADRB1) polymorphisms and response to bisoprolol treatment in beta-blocker naive patients with acute coronary syndrome (ACS).

Patients & methods

Seventy-seven patients received bisoprolol for four weeks. Blood pressure and heart rate were measured at baseline and during treatment. TaqMan allelic discrimination method was utilized for ADRB1 Ser49Gly and Arg389Gly genotyping.

Results

Arg389Arg carriers showed greater reductions in systolic and diastolic blood pressure (-8.5% ± 7.8% vs -0.76% ± 8.7%, p = 0.000218), and (-9.5% ± 9.7% vs -0.80% ± 11.5%, p = 0.000149), respectively, compared with Gly389 carriers. No statistical difference was found for study's outcomes based on codon 49.

Conclusion

Arg389Gly polymorphism is a promising bisoprolol response predictor in ACS patients.

Pharmacokinetics and Comparative Bioavailability of Test or Reference Capecitabine and Discrepant Pharmacokinetics Among Various Tumors in Chinese Solid Cancer Patients

The main objective of this study was to compare the pharmacokinetic (PK) bioequivalence of two capecitabine tablets and explore the different PK profiles of various tumors in Chinese patients with cancer. All 76 patients with a confirmed cancer diagnosis were included in this study. A single dose of 2000 mg of test or reference capecitabine (Xeloda, Hoffmann-La Roche) was orally administered postprandially. After 24 hours of washout, the patients were administered the test or the reference capecitabine alternately. PK samples were taken at the time of predose up to 6 hours postdose. Bioequivalence evaluation was performed using the geometric mean ratios of peak concentration in plasma (C_max) , area under the concentration-time curve from time 0 to 6 h (AUC_0-t) , and area under the concentration-time curve from time 0 to infinity (AUC_0-∞ ) for capecitabine and 5-fluorouracil (5-FU). In this study, 90% confidence intervals of test/reference mean ratios of C_max , AUC_0-t , AUC_0-∞ of capecitabine and 5-FU were in the range of 80%-125%. Both the test and reference capecitabine regimens were well tolerated in this study. Furthermore, we found that patients with esophageal-gastrointestinal cancers had higher exposure to capecitabine and a shorter time to C_max (T_max) than those with breast cancer. In conclusion, a single oral dose of 2000 mg of test capecitabine tablets after postprandial administration was bioequivalent to the reference drug.

Comparability of Foslevodopa/Foscarbidopa Pharmacokinetics in Healthy Asian and White Participants

This phase 1 study assessed the safety, tolerability, and pharmacokinetics of a single 24-hour continuous subcutaneous dose of foslevodopa/foscarbidopa in healthy adult Japanese (N = 24), Han Chinese (N = 8), and White (N = 24) participants. Three doses of foslevodopa/foscarbidopa were evaluated in healthy participants for this study: 480/24, 960/48, and 1440/72 mg/day. Serial blood samples for measurement of levodopa, carbidopa, foslevodopa, foscarbidopa, and 3-O-methyldopa concentrations were collected for 48 hours after foslevodopa/foscarbidopa administration. Safety and tolerability were assessed throughout the study. Point estimates for ratios of central values indicated that the exposure difference between Japanese and White participants was <10%. The maximum concentration and area under the plasma concentration-time curve for both LD and CD following foslevodopa/foscarbidopa continuous subcutaneous infusion were comparable between Han Chinese and White participants. Point estimates for ratios of central values indicated that the exposure difference between Han Chinese and White participants was <14%. The regimens tested were generally well tolerated, and no new safety issues were identified in this study. There were no clinically meaningful differences in LD and CD exposures or pharmacokinetics following administration of foslevodopa/foscarbidopa among White, Japanese, and Han Chinese participants.

Does Ethnicity Influence Recruitment into Clinical Trials of Parkinson's Disease?

BACKGROUND

Lack of participation of black and minority ethnic communities (BAME) in registered clinical trials is a concern as data emerging from these studies are used to licence new drugs or other interventions, even though findings made in such selected study populations have limited external validity in the aforesaid ethnic groups.

OBJECTIVE

We used Parkinson's disease (PD), the fastest rising neurodegenerative disorder in the world, as an exemplar condition to test our hypothesis that participants from BAME communities are underrepresented in clinical trials.

METHODS

A systematic search of clinical trials registered on a Clinicaltrials.gov database which queried for PD with racial distribution data from 2017 to 2021.

RESULTS

Out of 266 trials considered, 54 trials were published in peer reviewed journals. Among these, only 23 (42.65%) publications reported data regarding the racial distribution of the participants. Out of these, five studies involved mixed racial participation and two trials included black subjects.

CONCLUSION

We found that inclusion of under-represented BAME groups in recently published clinical trials is low, at only 21.57%, and is not even considered in most studies. Out of the reviewed trials, only 5 (21.75%) studies reported detailed demographic categories with black minorities enrolment. This constitutes a severe under-representation when compared to the proportion of Black or African American in the UK population (3%). Results of this study identified the need for better reporting of racial composition in clinical trials. We strongly recommend that future studies should consider ethnicity and other issues around diversity when designing and implementing the clinical trials, not only in the PD field but also beyond.

Inter-ethnic differences in pharmacokinetics-is there more that unites than divides?

Inter-ethnic variability in pharmacokinetics (PK) has been attributed to several factors ranging from genetic to environmental. It is not clear how current teaching in higher education (HE) reflects what published literature suggests on this subject. This study aims to gain insights into current knowledge about inter-ethnic differences in PK based on reports from published literature and current teaching practices in HE. A systematic literature search was conducted on PubMed and Scopus to identify suitable literature to be reviewed. Insights into inter-ethnic differences in PK teaching among educators in HE and industry were determined using a questionnaire. Thirty-one percent of the studies reviewed reported inter-ethnic differences in PK, of these, 37% of authors suggested genetic polymorphism as possible explanation for the inter-ethnic differences observed. Other factors authors proposed included diet and weight differences between ethnicities. Most respondents (80%) who taught inter-ethnic difference in PK attributed inter-ethnic differences to genetic polymorphism. While genetic polymorphism is one source of variability in PK, the teaching of genetic polymorphism is better associated with interindividual variabilities rather than inter-ethnic differences in PK as there are no genes with PK implications specific to any one ethnic group. Nongenetic factors such as diet, weight, and environmental factors, should be highlighted as potential sources of interindividual variation in the PK of drugs.

Pharmacodynamic and -kinetic Behavior of Low-, Intermediate-, and High-Dose Landiolol During Long-Term Infusion in Whites

Pharmacokinetics, pharmacodynamics, safety, and tolerability of long-term administration of landiolol, a fast-acting cardioselective β-blocker, were investigated for the first time in white subjects in a prospective clinical trial. Blood concentrations of landiolol and its metabolites, heart rate (HR), blood pressure (BP), and electrocardiogram parameters were studied in 12 healthy volunteers receiving continuous infusions of a new 12-mg/mL formulation of landiolol using a dose-escalation regimen (10 μg/kg BW/min for 2 hours, 20 μg/kg BW/min for 2 hours, 40 μg/kg BW/min for 20 hours, 6 hours follow-up). Landiolol blood concentrations were dose proportional. Time until steady state decreased with increasing doses. Pharmacokinetic parameters were t1/2 = 4.5 minutes, VD = 366 mL/kg, and total body clearance = 53 mL·kg·min. Maximal blood concentrations of the inactive main metabolite M1 were 10-fold higher than those of landiolol, with t1/2 = 126 minutes, VD = 811 mL/kg, and total body clearance = 4.5 mL·kg·min. HR reduction from baseline was fast (significant after 16 minutes) and sustained throughout the administration period. Systolic and diastolic BP reductions and electrocardiogram parameter changes were less pronounced and became significant only occasionally. Recovery after discontinuation of infusion was fast with little (HR) or no (BP) rebound. The new formulation showed excellent local and general tolerability.

Skepticism and pharmacophobia toward medication may negatively impact adherence to psychiatric medications: a comparison among outpatient samples recruited in Spain, Argentina, and Venezuela

BACKGROUND

Cultural differences in attitudes toward psychiatric medications influence medication adherence but transcultural studies are missing. The objective of this study was to investigate how attitudes and beliefs toward psychotropic medications influence treatment adherence in psychiatric outpatients in Spain, Argentina, and Venezuela.

METHODS

A cross-sectional, cross-cultural psychopharmacology study was designed to assess psychiatric outpatients' attitudes toward their prescribed medication. Patients completed the Drug Attitude Inventory - 10 Item (DAI-10), the Beliefs about Medicines Questionnaire - Specific Scale (BMQ-Specific), the Sidorkiewicz adherence tool, and sociodemographic and clinical questionnaires. The study included 1,291 adult psychiatric outpatients using 2,308 psychotropic drugs from three Spanish-speaking countries, the Canary Islands (Spain) (N=588 patients), Argentina (N=508), and Venezuela (N=195).

RESULTS

The univariate analyses showed different mean scores on the DAI-10 and the BMQ - Necessity and Concerns subscales but, on the other hand, the percentages of non-adherent and skeptical patients were relatively similar in three countries. Argentinian patients had a very low level of pharmacophobia. Multivariate analyses (logistic regression and chi-squared automatic interaction detector segmentation) showed that pharmacophobia in general and skepticism about specific medications (high concern about adverse reactions and low belief in their necessity) were associated with non-adherence. Pharmacophobia was the major factor associated with non-adherence (Spain and Venezuela) but when pharmacophobia was rare (Argentina), skepticism was the most important variable associated with non-adherence.

CONCLUSION

Psychiatric patients' attitudes and beliefs about their psychiatric treatment varied in these three Spanish-speaking countries, but pharmacophobia and skepticism appeared to play a consistent role in lack of adherence.

Pharmacogenomics of platinum-based chemotherapy response in NSCLC: a genotyping study and a pooled analysis

Published data showed inconsistent results about associations of extensively studied polymorphisms with platinum-based chemotherapy response. Our study aimed to provide reliable conclusions of these associations by detecting genotypes of the SNPs in a larger sample size and summarizing a comprehensive pooled analysis. 13 SNPs in 8 genes were genotyped in 1024 NSCLC patients by SequenomMassARRAY. 39 published studies and our study were included in meta-analysis. Patients with GA or GG genotypes of XRCC1 G1196 had better response than AA genotype carriers (Genotyping study: OR = 0.72, 95%CI: 0.53-0.96, P = 0.028; Meta-analysis: OR = 0.74, 95%CI: 0.62-0.89, P = 0.001). Patients carrying CT or TT genotypes of XRCC1 C580T could be more sensitive to platinum-based chemotherapy compared to patients with CC genotype (OR = 0.54, 95%CI: 0.37-0.80, P = 0.002). CC genotype of XRCC3 C18067T carriers showed more resistance to platinum-based chemotherapy when compared to those with CT or TT genotypes (OR = 0.69, 95%CI: 0.52-0.91, P = 0.009). Our study indicated that XRCC1 G1196A/C580T and XRCC3 C18067T should be paid attention for personalized platinum-based chemotherapy in NSCLC patients.

Gender-based personalized pharmacotherapy: a systematic review

PURPOSE

In general, male and female are prescribed the same amount of dosage even if most of the cases female required less dosage than male. Physicians are often facing problem on appropriate drug dosing, efficient treatment, and drug safety for a female in general. To identify and synthesize evidence about the effectiveness of gender-based therapy; provide the information to patients, providers, and health system intervention to ensure safety treatment; and minimize adverse effects.

METHODS

We performed a systematic review to evaluate the effect of gender difference on pharmacotherapy. Published articles from January 1990 to December 2015 were identified using specific term in MEDLINE (PubMed), EMBASE, and the Cochrane library according to search strategies that strengthen the reporting of observational and clinical studies.

RESULTS

Twenty-six studies fulfilled the inclusion criteria for this systematic review, yielding a total of 6309 subjects. We observed that female generally has a lower the gastric emptying time, gastric PH, lean body mass, and higher plasma volume, BMI, body fat, as well as reduce hepatic clearance, difference in activity of Cytochrome P450 enzyme, and metabolize drugs at different rate compared with male. Other significant factors such as conjugation, protein binding, absorption, and the renal elimination could not be ignored. However, these differences can lead to adverse effects in female especially for the pregnant, post-menopausal, and elderly women.

CONCLUSION

This systematic review provides an evidence for the effectiveness of dosage difference to ensure safety and efficient treatment. Future studies on the current topic are, therefore, recommended to reduce the adverse effect of therapy.

Efficacy and safety of levodopa-carbidopa intestinal gel from a study in Japanese, Taiwanese, and Korean advanced Parkinson's disease patients

In a previous multinational, randomized, double-blind, double-dummy study, levodopa–carbidopa intestinal gel (LCIG) was tolerable and significantly improved ‘off’ time in advanced Parkinson’s disease (PD) patients. However, efficacy and safety in the Asian population has not yet been demonstrated. In this open-label study, efficacy and safety of LCIG were assessed in Japanese, Korean, and Taiwanese advanced PD patients with motor complications not adequately controlled by available PD medication. The patients were treated with LCIG monotherapy for 12 weeks. The primary end point was the mean change from baseline to week 12 in ‘off’ time, as reported in the PD Symptom Diary, normalized to a 16 h waking day and analyzed by a mixed-model repeated-measures analysis. Adverse events (AEs) were recorded. Thirty-one patients were enrolled (23 Japanese, 4 Taiwanese, 4 Korean) and 28 (90%) completed the study. For those who completed the study, the mean (s.d.) total daily levodopa dose from LCIG was 1,206.3 (493.6) mg/day at final visit (n=28); last observation carried forward (n=30) was 1,227.6 (482.8) mg/day. There was a significant mean change (s.d.) of −4.6 (3.0) hours of ‘off’ time from baseline (mean (s.d.)=7.4 (2.3)) to week 12 (n=29), P<0.001. All the patients had an AE, with the most frequently reported being incision site pain (42%); 1 (3.2%) discontinued treatment because of an AE and later died because of sepsis, which the investigator considered unrelated to LCIG treatment. These results suggest that LCIG is efficacious and tolerable in Japanese, Taiwanese, and Korean advanced PD patients.

Jejunal Infusion of levodopa-carbidopa intestinal gel versus oral administration of levodopa-carbidopa tablets in japanese subjects with advanced Parkinson's disease: pharmacokinetics and pilot efficacy and safety

Background and Objective

Oral levodopa-carbidopa (LC-oral) treatment in advanced Parkinson’s disease (PD) is associated with motor complications due to large fluctuations in levodopa plasma concentrations. Levodopa–carbidopa intestinal gel (LCIG) provides individualized continuous levodopa–carbidopa delivery through intrajejunal infusion. This study evaluated the pharmacokinetics, safety, and efficacy of LCIG relative to LC-oral in Japanese subjects with advanced PD.

Methods

Subjects with advanced PD were converted from their anti-PD medications to individually optimized doses of LC-oral (10:1 levodopa:carbidopa ratio) for 28 days (baseline; period 1) followed by switching to intrajejunal infusion of LCIG (4:1 ratio) for 21 days (period 2). Pharmacokinetics, adverse events (AEs), and efficacy were assessed.

Results

Eight patients were enrolled. Six received LCIG and four reported at least one AE [most common: fall (33.3 %), dyskinesia (33.3 %)]; one discontinued due to an AE. The average daily dose was 1230/123 and 1370/342 mg levodopa/carbidopa for LC-oral and LCIG, respectively, at the end of each period. The degree of fluctuation and intra-subject variability of levodopa plasma concentrations were 5.5- and 4-fold lower, respectively, with LCIG than with LC-oral. Levodopa bioavailability was 99 % for LCIG relative to LC-oral. Compared with baseline, LCIG decreased “Off” time (2.68 h, P = 0.002) and increased “On” time without troublesome dyskinesia (2.35 h, P = 0.006) in the PD Diary^©. With the small sample size, no statistically significant changes were seen on other efficacy endpoints.

Conclusions

In Japanese subjects with advanced PD, LCIG resulted in an improved pharmacokinetic profile that appeared to be associated with reduced motor complications compared with LC-oral. These results extend previous findings in mainly Caucasian populations.

Impact of the β-1 adrenergic receptor polymorphism on tolerability and efficacy of bisoprolol therapy in Korean heart failure patients: association between β adrenergic receptor polymorphism and bisoprolol therapy in heart failure (ABBA) study

BACKGROUND/AIMS

We evaluated the association between coding region variants of adrenergic receptor genes and therapeutic effect in patients with congestive heart failure (CHF).

METHODS

One hundred patients with stable CHF (left ventricular ejection fraction [LVEF] < 45%) were enrolled. Enrolled patients started 1.25 mg bisoprolol treatment once daily, then up-titrated to the maximally tolerable dose, at which they were treated for 1 year.

RESULTS

Genotypic analysis was carried out, but the results were blinded to the investigators throughout the study period. At position 389 of the β-1 adrenergic receptor gene (ADRB1), the observed minor Gly allele frequency (Gly389Arg + Gly389Gly) was 0.21, and no deviation from Hardy-Weinberg equilibrium was observed in the genotypic distribution of Arg389Gly (p = 0.75). Heart rate was reduced from 80.8 ± 14.3 to 70.0 ± 15.0 beats per minute (p < 0.0001). There was no significant difference in final heart rate across genotypes. However, the Arg389Arg genotype group required significantly more bisoprolol compared to the Gly389X (Gly389Arg + Gly389Gly) group (5.26 ± 2.62 mg vs. 3.96 ± 2.05 mg, p = 0.022). There were no significant differences in LVEF changes or remodeling between two groups. Also, changes in exercise capacity and brain natriuretic peptide level were not significant. However, interestingly, there was a two-fold higher rate of readmission (21.2% vs. 10.0%, p = 0.162) and one CHF-related death in the Arg389Arg group.

CONCLUSIONS

The ADRB1 Gly389X genotype showed greater response to bisoprolol than the Arg389Arg genotype, suggesting the potential of individually tailoring β-blocker therapy according to genotype.

Interethnic differences in pharmacokinetics of antibacterials

BACKGROUND

Optimal antibacterial dosing is imperative for maximising clinical outcome. Many factors can contribute to changes in the pharmacokinetics of antibacterials to the extent where dose adjustment may be needed. In acute illness, substantial changes in important pharmacokinetic parameters such as volume of distribution and clearance can occur for certain antibacterials. The possibility of interethnic pharmacokinetic differences can further complicate attempts to design an appropriate dosing regimen. Factors of ethnicity, such as genetics, body size and fat distribution, contribute to differences in absorption, distribution, metabolism and elimination of drugs. Despite extensive previous work on the altered pharmacokinetics of antibacterials in some patient groups such as the critically ill, knowledge of interethnic pharmacokinetic differences for antibacterials is limited.

OBJECTIVES

This systematic review aims to describe any pharmacokinetic differences in antibacterials between different ethnic groups, and discuss their probable mechanisms as well as any clinical implications.

METHODS

We performed a structured literature review to identify and describe available data of the interethnic differences in the pharmacokinetics of antibacterials.

RESULTS

We found 50 articles that met our inclusion criteria and only six of these compared antibacterial pharmacokinetics between different ethnicities within the same study. Overall, there was limited evidence available. We found that interethnic pharmacokinetic differences are negligible for carbapenems, most β-lactams, aminoglycosides, glycopeptides, most fluoroquinolones, linezolid and daptomycin, whereas significant difference is likely for ciprofloxacin, macrolides, clindamycin, tinidazole and some cephalosporins. In general, subjects of Asian ethnicity achieve drug exposures up to two to threefold greater than Caucasian counterparts for these antibacterials. This difference is caused by a comparatively lower volume of distribution and/or drug clearance.

CONCLUSION

Interethnic pharmacokinetic differences of antibacterials are likely; however, the clinical relevance of these differences is unknown and warrants further research.

Applying genome-wide gene-based expression quantitative trait locus mapping to study population ancestry and pharmacogenetics

BACKGROUND

Gene-based analysis has become popular in genomic research because of its appealing biological and statistical properties compared with those of a single-locus analysis. However, only a few, if any, studies have discussed a mapping of expression quantitative trait loci (eQTL) in a gene-based framework. Neither study has discussed ancestry-informative eQTL nor investigated their roles in pharmacogenetics by integrating single nucleotide polymorphism (SNP)-based eQTL (s-eQTL) and gene-based eQTL (g-eQTL).

RESULTS

In this g-eQTL mapping study, the transcript expression levels of genes (transcript-level genes; T-genes) were correlated with the SNPs of genes (sequence-level genes; S-genes) by using a method of gene-based partial least squares (PLS). Ancestry-informative transcripts were identified using a rank-score-based multivariate association test, and ancestry-informative eQTL were identified using Fisher's exact test. Furthermore, key ancestry-predictive eQTL were selected in a flexible discriminant analysis. We analyzed SNPs and gene expression of 210 independent people of African-, Asian- and European-descent. We identified numerous cis- and trans-acting g-eQTL and s-eQTL for each population by using PLS. We observed ancestry information enriched in eQTL. Furthermore, we identified 2 ancestry-informative eQTL associated with adverse drug reactions and/or drug response. Rs1045642, located on MDR1, is an ancestry-informative eQTL (P = 2.13E-13, using Fisher's exact test) associated with adverse drug reactions to amitriptyline and nortriptyline and drug responses to morphine. Rs20455, located in KIF6, is an ancestry-informative eQTL (P = 2.76E-23, using Fisher's exact test) associated with the response to statin drugs (e.g., pravastatin and atorvastatin). The ancestry-informative eQTL of drug biotransformation genes were also observed; cross-population cis-acting expression regulators included SPG7, TAP2, SLC7A7, and CYP4F2. Finally, we also identified key ancestry-predictive eQTL and established classification models with promising training and testing accuracies in separating samples from close populations.

CONCLUSIONS

In summary, we developed a gene-based PLS procedure and a SAS macro for identifying g-eQTL and s-eQTL. We established data archives of eQTL for global populations. The program and data archives are accessible at http://www.stat.sinica.edu.tw/hsinchou/genetics/eQTL/HapMapII.htm. Finally, the results from our investigations regarding the interrelationship between eQTL, ancestry information, and pharmacodynamics provide rich resources for future eQTL studies and practical applications in population genetics and medical genetics.

A randomized placebo-controlled polysomnographic study of eszopiclone in Japanese patients with primary insomnia

OBJECTIVES

To evaluate the efficacy and dose-response effect of eszopiclone on sleep latency and sleep maintenance in Japanese patients with primary insomnia.

METHODS

In this randomized, double-blind, five-way crossover study, 72 patients received placebo, eszopiclone 1mg, 2mg, and 3mg, and zolpidem 10mg in random order for two consecutive nights with a washout period between treatments. Objective sleep measures from polysomnography (PSG) and subjective patient reports were collected.

RESULTS

All active treatments produced significant improvement in objective and subjective sleep latency compared with placebo (P<0.05 for all comparisons); linear dose-response relationships were observed for eszopiclone. PSG-determined wake time after sleep onset (WASO), sleep efficiency, and number of awakenings (NA), and patient-reported measures of WASO, NA, sleep quality, sleep depth, and daytime functioning significantly improved following treatment with eszopiclone 2mg and 3mg and zolpidem 10mg versus placebo (P<0.05). Eszopiclone at all doses increased total sleep time and stage 2 sleep time (P<0.001 for both comparisons), but did not alter REM or slow-wave sleep. Eszopiclone was generally well tolerated; the most frequently reported adverse event was mild dysgeusia.

CONCLUSIONS

In Japanese patients with primary insomnia, eszopiclone 2mg and 3mg significantly improved PSG-determined and patient-reported sleep latency and sleep maintenance relative to placebo.

Exploring differences in drug doses between Japan and Western countries

Japan is unique among Asian countries in that it requires inclusion of substantial domestic clinical trial data in new drug application data packages. Some question the need for this and call for globalization of approved doses. The current study examines international differences in maximum daily dose of drugs approved in Japan between 2001 and 2007, and for all cardiovascular system (CVS) and central nervous system (CNS) drugs marketed in Japan. For 32% of the drugs approved in Japan between 2001 and 2007, the maximum recommended dose in the United States was > or =2 times higher than the maximum dose approved in Japan. Dose differences were rare for antitumor and antiviral drugs and also for priority-review and orphan drugs. Of all the price-listed CVS drugs currently available in Japan, 65% had maximum doses that were > or =2 times higher in the Netherlands than in Japan; similarly, 57% of the drugs had maximum doses that were > or =2 times higher in the United States than in Japan. For CNS drugs, these figures were 32% (the Netherlands) and 29% (United States). These results underscore the necessity to carry out quantitative analyses to determine the causes of these differences.

Pharmacokinetics of indinavir in Koreans and Caucasians

We evaluated whether the pharmacokinetic parameters of indinavir differ in Koreans and Caucasians. Indinavir was administered orally to 8 healthy Koreans and 4 healthy Caucasians, and plasma indinavir levels were quantified by high performance liquid chromatography. No significant differences were observed in terms of its pharmacokinetic parameters; however, the AUC difference between the 2 groups may be significant for larger sample sizes.

Determination of phenobarbitone population clearance values for physically and mentally handicapped Chinese children with epilepsy

OBJECTIVE

To estimate population clearance values of phenobarbitone in epileptic children of Chinese origin in Hong Kong.

METHOD

Steady-state concentration data were gathered during routine care at a special chronic centre for the physically and mentally handicapped. Age, gender, body weight and concurrent medication (taking additional carbamazepine (CBZ) or phenytoin (PTO)) were the four fixed effects tested simultaneously for their influence on the population mean of phenobarbitone clearance, using the nonlinear mixed-effects model.

RESULTS

No age or gender-related effect was found. Both body weight and concurrent medication were the important determinants of phenobarbitone clearance. The population mean values of phenobarbitone clearance obtained were 0.250 litres/day/kg for children on phenobarbitone only and 0.208 litres/day/ kg for those on concomitant CBZ or PTO. Their corresponding interindividual and intraindividual variability values were 34.9% and 15.1% for mono-pharmacy and 29.3% and 7.84% for polypharmacy patient groups.

CONCLUSION

The correlation between phenobarbitone clearance and body weight found may allow dosage adjustment to be made to achieve target steady-state plasma concentrations.

Distribution of gemcitabine pathway genotypes in ethnic Asians and their association with outcome in non-small cell lung cancer patients

OBJECTIVE

Pharmacogenetics suggests variants of genes involved in gemcitabine pharmacology could be useful markers for predicting inter-ethnic and inter-patient outcomes from treatment with the agent. Here, we have characterized the distribution of variants of genes involved in gemcitabine pharmacology in ethnic Asian populations and their association with non-small cell lung cancer (NSCLC) patient outcome.

METHODS

All genes involved in gemcitabine transport, metabolism and activity were screened for suitable variants for analysis using publications and public databases. By pyrosequencing, the frequency of qualifying variants was characterized from germline DNA of 94 healthy Asian donors and 53 NSCLC patients receiving gemcitabine-based chemotherapy.

RESULTS

Significant differences in genotype distribution between Caucasians and Asians were seen at 10/25 (45%) variant loci. In NSCLC patients, CDA+435 C>T variants were associated with response (p=0.026) and time to progression (p=0.016) and SLC28A1+1561 G>A variants were associated with neutropenia (p=0.030) and thrombocytopenia nadir (p=0.037).

CONCLUSIONS

Many genotypes in gemcitabine pharmacology vary in their frequency between Caucasians and Asians. CDA+435, and SLC28A1+1561 are worthy of further investigation as potential indicators of patient outcome after gemcitabine treatment.

Interethnic Differences in Drug Response: The Contribution of Genetic Variability in β Adrenergic Receptor and Cytochrome P4502C9

Ethnic differences in drug response have been extensively reported, and ethnicity has been suggested to be useful clinically as a predictor of drug response. Genetic polymorphisms in the genes encoding beta(1) adrenergic receptor (AR) and beta(2) AR, targets of beta AR antagonists, and in cytochrome P4502C9, the enzyme involved in warfarin metabolism, have the potential to explain some of the observed ethnic variability in drug response and to improve clinical practice.

Ethnopharmacology: understanding how ethnicity can affect drug response is essential to providing culturally competent care

Ethnopharmacologic research has revealed that ethnicity significantly affects drug response. Genetic or cultural factors, or both, may influence a given drug's pharmacokinetics (its absorption, metabolism, distribution, and elimination) and pharmacodynamics (its mechanism of action and effects at the target site), as well as patient adherence and education. In addition, the tremendous variation within each of the broader racial and ethnic categories defined by the U.S. Census Bureau (categories often used by researchers) must be considered. Nurses need to become knowledgeable about drugs that are likely to elicit varied responses in people with different ethnic backgrounds, as well as the potential for adverse effects. The existing ethnopharmacologic research focuses primarily on psychotropic and antihypertensive agents, as does this article. Cultural assessment of every patient is vital; thus Leininger's Sunrise Model and Giger and Davidhizar's Transcultural Assessment Models are briefly described as well.

Association of race, heart failure and chronic kidney disease

Heart failure and kidney disease are two important emerging epidemics. The importance of pre-end stage kidney disease was introduced in the 2002 publication of the National Kidney Foundation's Chronic Kidney Disease Guidelines. One in nine US adults has some degree of kidney disease, many of whom also have heart failure. Among all patients with heart failure, approximately half have significant kidney disease. The distribution of etiologies of these conditions varies among races; blacks tend to have heart and kidney disease predominantly due to hypertension, while whites tend to be affected by ischemic heart disease and Hispanics by diabetic kidney disease. The burden of disease is disproportionately borne by minorities, the cause of which remains to be fully elucidated. The bulk of knowledge of these diseases is based on studies involving predominantly white subjects. Recent studies have suggested that there are racial differences in patients' responsiveness to various classes of drugs. Designs of future studies should take into account these differences.

Ethnic or Racial Differences Revisited

Ethnic or racial differences in pharmacokinetics and pharmacodynamics have been attributed to the distinctions in the genetic, physiological and pathological factors between ethnic/racial groups. These pharmacokinetic/pharmacodynamic differences are also known to be influenced by several extrinsic factors such as socioeconomic background, culture, diet and environment. However, it is noted that other factors related to dosage regimen and dosage form have largely been ignored or overlooked when conducting or analysing pharmacokinetic/pharmacodynamic studies in relation to ethnicity/race. Potential interactions can arise between the characteristics of ethnicity/race and a unique feature of dosage regimen or dosage form used in the study, which may partly account for the observed pharmacokinetic/pharmacodynamic differences between ethnic/racial groups. Ethnic/racial differences in pharmacokinetics/pharmacodynamics can occur from drug administration through a specific route that imparts distinct pattern of absorption, distribution, transport, metabolism or excretion. For example, racial differences in the first-pass metabolism of a drug following oral administration may not be relevant when the drug is applied to the skin. On the other hand, ethnic/racial difference in pharmacokinetics/pharmacodynamics can also happen via two different routes of drug delivery, with varying levels of dissimilarity between routes. For example, greater ethnic/racial differences were observed in oral clearance than in systemic clearance of some drugs, which might be explained by the pre-systemic factors involved in the oral administration as opposed to the intravenous administration. Similarly, changes in the dose frequency and/or duration may have profound impact on the ethnic/racial differences in pharmacokinetic/pharmacodynamic outcome. Saturation of enzymes, transporters or receptors at high drug concentrations is a possible reason for many observed ethnic/racial discrepancies between single- and multiple-dose regimens, or between low- and high-dose administrations. The presence of genetic polymorphism of enzymes and/or transporters can further complicate the analysis of pharmacokinetic/pharmacodynamic data in ethnic/racial populations. Even within the same dosage regimen, the use of different dosage forms may trigger significantly different pharmacokinetic/pharmacodynamic responses in various ethnic/racial groups, given that different dosage forms may exhibit different rates of drug release, may release the drug at different sites, and/or have different retention times at specific sites of the body. It is thus cautioned that the pharmacokinetic/pharmacodynamic data obtained from different ethnic/racial groups cannot be indiscriminately compared or combined for analysis if there is a lack of homogeneity in the apparent 'extrinsic' factors, including dosage regimen and dosage form.

Ethnopharmacology

Ethnopharmacologic research has revealed that ethnicity significantly affects drug response. Genetic or cultural factors, or both, may influence a given drug's pharmacokinetics (its absorption, metabolism, distribution, and elimination) and pharmacodynamics (its mechanism of action and effects at the target site), as well as patient adherence and education. In addition, the tremendous variation within each of the broader racial and ethnic categories defined by the U.S. Census Bureau (categories often used by researchers) must be considered. Nurses need to become knowledgeable about drugs that are likely to elicit varied responses in people with different ethnic backgrounds, as well as the potential for adverse effects. The existing ethnopharmacologic research focuses primarily on psychotropic and anti-hypertensive agents, as does this article. Cultural assessment of every patient is vital; thus Leininger's Sunrise Model and Giger and Davidhizar's Transcultural Assessment Models are briefly described as well.

Population characteristics in cervical cancer trials: search for external validity

OBJECTIVE

The purpose of this study was to compare the characteristics of patients with cervical cancer who were enrolled in cooperative group trials with characteristics of the cervical cancer population of the United States and to determine the generalizability of the results of those trials to the disease population in the United States.

STUDY DESIGN

Phase III trials in cervical cancer that were conducted by cooperative groups in the United States from 1981 through 1997 were identified. These groups were placed into 4 categories on the basis of disease stage and primary treatment modality: Stage IB, negative pelvic nodes that were treated with radical hysterectomy (n = 277 patients); Stage IB-IIA, positive pelvic nodes that were treated with radical hysterectomy (n = 239 patients); Stage IB 2 , negative pelvic and para-aortic nodes that were treated with radiation therapy (n = 369 patients); and Stage IIB-IVA, negative para-aortic nodes that were treated with radiation therapy (n = 1190 patients). For each category, comparable patients from the Surveillance, Epidemiology, and End Results (SEER) database were identified. The age and ethnic distributions of each study population and the distributions of the SEER program were compared.

RESULTS

The age distributions were equivalent, except for patients with IB 2 disease that was treated with radiation therapy where cooperative group subjects were more likely to be younger than 50 years, (odds ratio, 0.17; 95% CI, 0.11-0.26). A statistically significant higher proportion of black and Hispanic women enrolled in cooperative group studies in comparison with surveillance, epidemiology, and end results.

CONCLUSION

Hispanic and black women were recruited proportionately to cooperative group randomized cervical cancer trials in comparison to the United States population. The age distribution of the clinical trial population is also comparable to that of the general population.

Differences in drug pharmacokinetics between East Asians and Caucasians and the role of genetic polymorphisms

Interethnic variability in pharmacokinetics can cause unexpected outcomes such as therapeutic failure, adverse effects, and toxicity in subjects of different ethnic origin undergoing medical treatment. It is important to realize that both genetic and environmental factors can lead to these differences among ethnic groups. The International Conference on Harmonization (ICH) published a guidance to facilitate the registration of drugs among ICH regions (European Union, Japan, the United States) by recommending a framework for evaluating the impact of ethnic factors on a drug's effect, as well as its efficacy and safety at a particular dosage and dosage regimen. This review focuses on the pharmacokinetic differences between East Asians and Caucasians. Differences in metabolism between East Asians and Caucasians are common, especially in the activity of several phase I enzymes such as CYP2D6 and the CYP2C subfamily. Before drug therapy, identification of either the genotype and/or the phenotype for these enzymes may be of therapeutic value, particularly for drugs with a narrow therapeutic index. Furthermore, these differences are relevant for international drug approval when regulatory agencies must decide if they accept results from clinical trials performed in other parts of the world.

Toward individualized pharmaceutical care of East Asians: the value of genetic testing for polymorphisms in drug-metabolizing genes

Research into the relationship between genetics and drug response has focused on polymorphisms in genes that encode drug-metabolizing enzymes, particularly the genes of cytochrome P450 superfamily 2, which affect the clearance of the anticoagulant warfarin, proton pump inhibitors, tricyclic antidepressants, and many other clinically relevant drugs. Much of this work has targeted East Asians, a genetically distinguishable and populous group. Researchers have identified polymorphisms that inactivate gene function, compared polymorphism frequencies in East-Asian and Caucasian populations, and determined the effects on the pharmacokinetic parameters of drugs. Detection in an individual of polymorphisms known to inactivate a drug-metabolizing enzyme is predictive of poor metabolism of drugs processed by that pathway, which itself may be predictive of an atypical drug response. Genetic tests can be used to screen for individuals with poor metabolizer phenotypes, with the ultimate goal of predicting the clinical effects of drugs.

Pharmacokinetics and Metabolic Rates of Acetyl Salicylic Acid and Its Metabolites in an Otomi Ethnic Group of Mexico

The objective of this study was to determine pharmacokinetic differences of acetyl salicylic acid (ASA) and its metabolites: gentisic acid (GA), salicylic acid (SA) and salicyluric acid (SUA) between Otomies and Mesticians healthy subjects. Design. Ten Otomies and 10 Mesticians were included. After a single dose of aspirin given orally (15 mg/kg), blood and urine samples were collected at different times. Results. Pharmacokinetic parameters of salicylates showed significant differences, except distribution volume of SA, and elimination half-life of SUA. Metabolic rates of ASA showed significant differences for all rates between both groups. On the other hand, percentages of dose excreted were more reduced for SA and SUA for the Otomies than for the Mesticians. Conclusion. Results reflect differences in the hydrolysis way i.e. from ASA to SA and aromatic hydroxylation i.e. from SA to GA, which were slower in Otomies subjects, showing a possible pharmacokinetic differences about the capabilities of ASA biotransformation as a consequence of ethnic differences.

A review and assessment of potential sources of ethnic differences in drug responsiveness

The International Conference on Harmonization (ICH) E5 guidelines were developed to provide a general framework for evaluating the potential impact of ethnic factors on the acceptability of foreign clinical data, with the underlying objective to facilitate global drug development and registration. It is well recognized that all drugs exhibit significant inter-subject variability in pharmacokinetics and pharmacologic response and that such differences vary considerably among individual drugs and depend on a variety of factors. One such potential factor involves ethnicity. The objective of the present work was to perform an extensive review of the world literature on ethnic differences in drug disposition and responsiveness to determine their general significance in relation to drug development and registration. A few examples of suspected ethnic differences in pharmacokinetics or pharmacodynamics were identified. The available literature, however, was found to be heterologous, including a variety of study designs and research methodologies, and most of the publications were on drugs that were approved a long time ago.

CYP3A4*1B and NAT2*14 alleles in a native African population

Single nucleotide polymorphisms were examined in the cytochrome 450 3A4 (CYP3A4) and N-acetyltransferase 2 (NAT2) genes, which code for major mediators of the metabolism of a wide variety of therapeutic drugs, as well as xenobiotics. We determined, in a population from Guinea-Bissau, the frequencies of CYP3A4 and NAT2 variants expected to be prevalent among Africans, due to the high frequency previously observed in African Americans. The observed frequencies were 72% for CYP3A4*1B and 19.2% for the NAT2 191 G>A variant. The high frequency found for these potentially function-altering polymorphisms suggests the possibility of impaired metabolism through CYP3A4 and NAT2 in this population. Strikingly, the frequency observed for the NAT2 191 G>A single nucleotide polymorphism (SNP), associated with the slow acetylator phenotype, was significantly higher than found in other African populations, suggesting the existence of a west to east gradient across Sub-Saharan Africa. The prevalence of these variants may be relevant with regard to therapeutic efficacy in African populations for it may potentially affect drug clearance and consequently, increase the incidence of side effects and drug-drug interactions.

Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.

Treatment choices and response rates in African-American women with breast carcinoma

BACKGROUND

Breast cancer mortality rates are higher among African-American women compared with white American women, yet little is known regarding ethnicity-related variation in patterns of primary surgical treatment, locoregional recurrence rates, and response to induction chemotherapy.

METHODS

The available literature was reviewed to evaluate outcome from breast-conservation therapy in African-American women and response rates to systemic therapy.

RESULTS

Breast-conservation therapy appears to be underused among African-American women, a pattern that is noted also among white women with breast carcinoma. Higher rates of locoregional recurrence are seen among African-American women regardless of whether they receive breast-conserving treatment or undergo mastectomy, and this appears to be a function of primary tumor biology. Response rates to appropriately delivered systemic therapy are similar for African-American patients and white patients.

CONCLUSIONS

Despite the apparent increased aggressiveness of disease seen in African-American women with breast carcinoma, patterns of response to local and systemic therapy are similar to the patterns seen in white women with breast carcinoma.

The molecular and enzyme kinetic basis for the diminished activity of the cytochrome P450 2D6.17 (CYP2D6.17) variant. Potential implications for CYP2D6 phenotyping studies and the clinical use of CYP2D6 substrate drugs in some African populations

In this study, the basis for the diminished capacity of CYP2D6.17 to metabolise CYP2D6 substrate drugs and the possible implications this might have for CYP2D6 phenotyping studies and clinical use of substrate drugs were investigated in vitro. Enzyme kinetic analyses were performed with recombinant CYP2D6.1, CYP2D6.2, CYP2D6.17 and CYP2D6.T107I using bufuralol, debrisoquine, metoprolol and dextromethorphan as substrates. In addition, the intrinsic clearance of 10 CYP2D6 substrate drugs by CYP2D6.1 and CYP2D6.17 was determined by monitoring substrate disappearance. CYP2D6.17 exhibited generally higher K(m) values compared to CYP2D6.1. The V(max) values were generally not different except for metoprolol alpha-hydroxylation with the V(max) value for CYP2D6.17 being half that of CYP2D6.1. CYP2D6.1 and CYP2D6.2 displayed similar kinetics with all probe drugs except for dextromethorphan O-demethylation with the intrinsic clearance value of CYP2D6.2 being half that of CYP2D6.1. CYP2D6.17 exhibited substrate-dependent reduced clearances for the 10 substrates studied. In a clinical setting, the clearance of some drugs could be affected more than others in individuals with the CYP2D6(*)17 variant. The CYP2D6(*)17 allele might, therefore, contribute towards the poor correlation of phenotyping results when using different probe drugs in African populations. To investigate effects of CYP2D6(*)17 mutations on the structure of the enzyme, a homology model of CYP2D6 was built using the CYP2C5 crystal structure as a template. The results suggest an alteration in position of active-site residues in CYP2D6.17 as a possible explanation for the reduced activity of the enzyme.

Extrapyramidal symptom profiles in Japanese patients with schizophrenia treated with olanzapine or haloperidol

Previous clinical trials have clearly shown the superiority of olanzapine to haloperidol in the improvement of extrapyramidal symptoms (EPS) in schizophrenic patients. The primary purpose of this study was to compare EPS profiles in Japanese schizophrenic patients treated with an atypical antipsychotic, olanzapine, or a typical antipsychotic, haloperidol, as measured by the Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). The DIEPSS, which consists of eight individual parameters and one global assessment (overall severity), was used to evaluate 182 patients enrolled in this 8-week study. The primary safety analysis was maximum change (that could be either a decrease or increase) from baseline in DIEPSS total score. Secondary analyses included change from baseline to maximum in DIEPSS total score, change from baseline to endpoint (LOCF) in DIEPSS total score, and the rank sum of the maximum change (that could be either a decrease or increase) from baseline in the DIEPSS individual items. Incidence of treatment-emergent EPS adverse events using the DIEPSS scale was also analyzed. The olanzapine group showed statistically significant superiority to the haloperidol group on the primary analysis (p<0.001). Secondary analyses also demonstrated olanzapine's superiority in DIEPSS total, parkinsonism, akathisia and overall severity scores (all p< or =0.014). Categorical analysis of treatment-emergent akathisia and parkinsonism syndromes at endpoint showed improvement in the olanzapine group but worsening in the haloperidol group. The results from this study suggest that olanzapine, as in Caucasian populations, is a safe treatment in Japanese patients chronically ill with schizophrenia.

Effect of race and sex on single and multiple dose pharmacokinetics of desloratadine

OBJECTIVE

This study was designed to characterise the single and multiple dose pharmacokinetic profile of desloratadine, a new antihistamine, and its main metabolite, 3-hydroxy (3-OH) desloratadine, in healthy volunteers differing in sex and race.

DESIGN

An open-label, parallel-group, single- and multiple-dose pharmacokinetic trial.

INTERVENTION

A single 7.5mg oral tablet of desloratadine on day 1, followed by 7.5mg daily doses on days 4 to 17.

PARTICIPANTS

48 healthy, nonsmoking volunteers (12 White men, 12 Black men, 12 White women, 12 Black women).

MAIN OUTCOME MEASURES

AUC(24h) and C(max) determined from serial blood samples of desloratadine and 3-OH desloratadine.

RESULTS

There were no clinically relevant differences between men and women or Black participants and White participants for desloratadine and 3-OH desloratadine maximum plasma concentrations (C(max)) and area under the plasma concentration-time curve (AUC). Following multiple doses, the geometric mean C(max) was 5.17 microg/L in men, 5.68 microg/L in women, 5.87 microg/L in Black participants and 5.00 microg/L in White participants; the corresponding AUC from 0 to 24 hours (AUC(24h)) values were 77.9, 80.0, 90.6 and 68.8 micro g/L x h. Corresponding 3-OH desloratadine geometric mean C(max) values were 1.93, 2.79, 2.20 and 2.45 microg/L, and the AUC(24h) values were 32.1, 47.5, 37.1 and 41.1 microg/L. h.

CONCLUSIONS

Oral administration of multiple doses of desloratadine 7.5mg, a dose 50% higher than the recommended 5mg clinical dose, was well tolerated by healthy adults differing in sex and race. Comparison of the C(max) and AUC values following 14 days of treatment with desloratadine indicates that no dosage adjustment is needed on the basis of sex or race.

Slower metabolism and reduced intake of nicotine from cigarette smoking in Chinese-Americans

BACKGROUND

Lung cancer rates are lower in Asians and Latinos than in whites. Ethnic differences in nicotine metabolism might explain, in part, ethnic differences in cigarette consumption and/or nicotine intake per cigarette and resultant tobacco-related cancer risk. We compared the rate of nicotine metabolism and the intake of nicotine per cigarette smoked among smokers of different ethnicities.

METHODS

Healthy volunteer smokers, including 37 Chinese-Americans, 40 Latinos, and 54 whites, received simultaneous infusions of deuterium-labeled nicotine and cotinine, a metabolite of nicotine. From blood and urine measurements, the disposition kinetics and daily intake of nicotine from smoking were determined. All statistical tests were two-sided.

RESULTS

Total and nonrenal clearance of nicotine and cotinine and metabolic clearance of nicotine via the cotinine pathway were similar in Latinos and whites and statistically significantly lower in Chinese-Americans. Intake of nicotine per cigarette by Chinese-Americans (0.73 mg; 95% confidence interval [CI] = 0.53 to 0.94 mg) was statistically significantly lower than that by Latinos (1.05 mg; 95% CI = 0.85 to 1.25 mg) or whites (1.10 mg; 95% CI = 0.91 to 1.30 mg; P =.039). Among all of the participants, there was a statistically significant positive correlation between nicotine clearance and daily intake of nicotine from cigarette smoking and between nicotine clearance and nicotine intake per cigarette (r =.41 and r =.39, respectively) (P<.001 for both).

CONCLUSIONS

The lower nicotine (and, therefore, tobacco smoke) intake per cigarette and the fewer cigarettes smoked per day, which may result, in part, from slower clearance of nicotine, may explain lower lung cancer rates in Chinese-Americans. Lower lung cancer rates among Latinos compared with whites, given their similar nicotine intake per cigarette, are probably due to smoking fewer cigarettes. The results with Chinese-Americans may have implications for dosing with nicotine medications to aid smoking cessation in Chinese- American smokers and perhaps in other Asian smokers.

Cultural competence: cardiovascular medications

Interethnic or racial differences are associated with enzyme polymorphisms, which are tiny variations in individuals in the physiology, absence, or presence of drug-metabolizing enzymes. The largest class of cardiovascular drugs investigated in pharmacogenetic studies is the antihypertensives. A number of studies have examined the best choices of antihypertensives for individuals within selected racial and ethnically defined populations. There is a fairly strong consensus about the pattern of antihypertensive treatment for black patients, but clear treatment directives for antihypertensive patients with other cultural affiliations have not emerged. Less information is reported about racial, ethnic, or cultural differences in effectiveness for other cardiovascular drugs. Nurses should consider whether the ethnic or racial affiliation of the patient places him or her more at risk for impaired drug metabolism. This article contains a guide for nursing assessment of culturally important factors related to polymorphisms.

SERMs, ethnicity, and clinical trials: opportunities and challenges

Selective estrogen receptor modulators (SERMs) are an exciting new class of pharmacotherapeutics that may have application in a wide variety of disease states. The science, both basic and clinical, that would guide the usage of these agents is in some respects at a relatively early developmental stage. Thus, the research community has an opportunity, before their use becomes widespread, to structure clinical trials such that the most complete profiles of benefits and risks are described. Tamoxifen is the SERM that has been most extensively studied and for which there are indications for both treatment and prevention of breast cancer based on trials involving more than 50,000 women. Despite this seemingly adequate sample size, an extremely important question remains unanswered--namely, whether there are ethnic differences in benefit and adverse effects of SERMs. It has generally been the case that new pharmacologic agents are tested in relatively small numbers of subjects, often only male, in North America and western Europe. While the populations are multi-ethnic, clinical trial subjects are most often not representative of the ethnic variability of these areas. Guidelines for usage of new drugs based on data from small, ethnically limited population groups are then generalized to other population groups, without consideration that differences in drug metabolism and/or responsiveness might exist.