An Investigation in the Comparability of the Exposure and Recommended Dose of Selected Pfizer Drugs in East Asian Countries: Is Mutual Usage of Clinical Data Among East Asian Countries Feasible?

The current regulatory path for new drug registration in East Asian countries has led to significant delay of the new medicines in these countries. A unified regulatory path and allowance of mutual usage of clinical data in East Asian countries would lead to cost saving in drug development and expedite the new drug registration in these countries. The objectives of the present analysis are to compare the approval dates of a selection of products developed by Pfizer in the United States and East Asian countries (China, Japan, Korea) and compare the pharmacokinetics and recommended doses of these products in East Asian countries. Eighteen products (20 drugs, 2 products with 2 combination drugs) with exposure data available in at least 2 of the 3 East Asian countries across different therapeutic areas were included in the analyses. The results showed that most products had delayed approval in East Asian countries (up to 8 years) after US or EU approval. No distinct differences were observed in the drug exposure and recommended doses for the selected products in East Asian countries. These results together with literature data of genetic similarity of the East Asian populations support the mutual usage of the clinical data in the East Asian countries for expedited regulatory submission and approval.

Implications of a defined daily dose fixed database for drug utilization research studies: The case of statins in Portugal

AIMS

Given the discrepancies between PDDs (prescribed daily doses) and DDDs (defined daily doses), we aimed to assess the extent of error in the results of an 18-year population-level study on statin utilization in Portugal.

METHODS

The Portuguese regulatory agency provided data for the period 2000-2018 on statin dispensing (C10AA). The DDDs were gathered from the ATC/DDD database. DDDs were calculated by the DDD year-by-year approach (DDD_YEAR ) and by the DDD last-year approach (DDD_LAST ). PDDs were calculated according to the year-by-year approach (PDD_YEAR ). Statin annual utilization rates per 1000 inhabitants per day were also calculated. Percent errors were calculated for PDD_YEAR and DDD_YEAR units.

RESULTS

The DDD_YEAR approach revealed decreases in the consumption of atorvastatin, fluvastatin, lovastatin, pravastatin and simvastatin in 2009, when their DDD was modified. Conversely, the results from both DDD_LAST and PDD_YEAR approaches indicated gradual changes in the actual consumption of all statins in Portugal. Before 2009, atorvastatin, pravastatin and simvastatin utilization was greatly overestimated by DDD_YEAR /1000 inhabitants/day. The average dose of lovastatin prescribed in the past 18 years (20 mg) was below the assigned DDDs during the study period, varying from 30 mg to 45 mg. Conversely, the PDD for fluvastatin was above the DDD values (ranging from 40 mg in 2000 to 70 mg in 2016). For atorvastatin, pravastatin and simvastatin, national PDDs were above the assigned DDD until the DDD modification in 2009.

CONCLUSIONS

A more dynamic system, based on national and annually updated DDDs, should be able to reduce discrepancies between DDDs and PDDs and the bias in utilization studies.

Impact of prednisolone dosage in the CHOP regimen for follicular lymphoma: a retrospective study

Rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) is one of the standard regimens for indolent B-cell non-Hodgkin's lymphoma (NHL). It is unclear whether the prednisolone (PSL) dosage affects the therapeutic effect or the adverse event profile. We retrospectively examined 48 patients with indolent B-cell NHL who were treated with R-CHOP (PSL 50 mg/m²/day for 5 days) at our institute between 2006 and 2016. We compared them with 149 patients with indolent B-cell lymphoma who were treated with R-CHOP (PSL 100 mg for 5 days) in the JCOG 0203 trial. The proportions of patients with bulky disease, extranodal involvement, and increased nodal sites were higher at our institute. Nevertheless, there was no difference in the CR rate, PFS, OS or the frequency of adverse events, except for peripheral neuropathy, between the two treatment groups. In our institute, there was no difference in the CR rate, PFS, OS or adverse event profile between patients who received PSL at 60-80 mg/day and at 81-100 mg/day. Patients who received PSL at 60-80 mg/day included many female and light-weight patients. In conclusion, the PSL dose adjusted based on body surface area appeared to be appropriate in terms of efficacy and safety.

Characteristics on Drug Safety Measures in Japan Stratified by System Organ Classes and Therapeutic Categories in Relation to the Approval Date

Revisions of drug package inserts (PIs) may be made immediately after approval or after considerable clinical experience; however, it is unclear whether there is a relationship between the characteristics of these safety measures and the period since drug approval. Here, we analyzed 209 cases of safety measures (revisions of the PIs) taken in Japan over 5 years (FY2014 to FY2018). The median, minimum, and maximum period from approval date in Japan to PI revision date was 6.29 years (interquartile range 2.68-15.53 years), 0.16 years, and 59.69 years, respectively. The cases were classified into four groups depending on types of adverse reaction and therapeutic category in relation to the national approval date and international birth date, resulting in the grouping together of particular adverse reactions and therapeutic drugs. For example, "Hepatobiliary disorders", "Blood and lymphatic system disorders", "Respiratory, thoracic and mediastinal disorders", "Antineoplastics", "Chemotherapeutics", and "Other agents affecting metabolism" were associated with the group of safety measures taken early after approval of a drug soon after the international birth date, suggesting that careful attention at an earlier stage after approval is necessary for these adverse reactions and drugs. Understanding such features of PI revisions makes pharmacovigilance planning more appropriate, contributing to the implementation of rapid and proper safety measures after drug approval.

Precision medicine: does ethnicity information complement genotype-based prescribing decisions?

Inter-ethnic differences in drug response are all too well known. These are underpinned by a number of factors, including pharmacogenetic differences across various ethnic populations. Precision medicine relies on genotype-based prescribing decisions with the aim of maximizing efficacy and mitigating the risks. When there is no access to genotyping tests, ethnicity is frequently regarded as a proxy of the patient's probable genotype on the basis of overall population-based frequency of genetic variations in the ethnic group the patient belongs to, with some variations being ethnicity-specific. However, ever-increasing transcontinental migration of populations and the resulting admixing of populations have undermined the utility of self-identified ethnicity in predicting the genetic ancestry, and therefore the genotype, of the patient. An example of the relevance of genetic ancestry of a patient is the inadequate performance of European-derived pharmacogenetic dosing algorithms of warfarin in African Americans, Brazilians and Caribbean Hispanics. Consequently, genotyping a patient potentially requires testing for all known clinically actionable variants that the patient may harbour, and new variants that are likely to be identified using state-of the art next-generation sequencing-based methods. Furthermore, self-identified ethnicity is associated with a number of ethnicity-related attributes and non-genetic factors that potentially influence the risk of phenoconversion (genotype-phenotype discordance), which may adversely impact the success of genotype-based prescribing decisions. Therefore, while genotype-based prescribing decisions are important in implementing precision medicine, ethnicity should not be disregarded.

Genetic polymorphisms of metabolic enzymes and the pharmacokinetics of indapamide in Taiwanese subjects

To understand the genetic makeup and impact on pharmacokinetics (PK) in the Taiwanese population, we analyzed the pharmacogenetic (PG) profile and demonstrated its effects on enzyme metabolism using indapamide as an example. A multiplex mass spectrometry method was used to examine the single nucleotide polymorphism (SNP) profile of eight major phases I and II metabolic enzymes in 1,038 Taiwanese subjects. A PG/PK study was conducted in 24 healthy subjects to investigate the possible effects of 28 SNPs on drug biotransformation. Among the genetic profile analyzed, eight SNPs from CYP2A6, CYP2C19, CYP2D6, CYP2E1, CYP3A5, and UGT2B7 showed higher variant frequencies than those previously reported in Caucasians or Africans. For instance, we observed 14.7% frequency of the SNP rs5031016 (I471T) from CYP2A6 in Taiwanese, whereas 0% variation was reported in Caucasians and Africans. The PG/PK study of indapamide demonstrated that the polymorphic SNPs CYP2C9 rs4918758 and CYP2C19 rs4244285 appeared to confer lowered enzyme activity, as indicated by increased C max (25% ∼ 64%), increased area under the plasma level-time curves (30~76%), increased area under the time infinity (43% ∼ 80%), and lower apparent clearance values than PK for wild-type indapamide. Our results reinforce the biochemical support of CYP2C19 in indapamide metabolism and identify a possible new participating enzyme CYP2C9. The PG/PK approach contributed toward understanding the genetic makeup of different ethnic groups and associations of enzymes in drug metabolism. It could be used to identify two genetic markers that enable to differentiate subjects with varied PK outcomes of indapamide.

Approaches to Japanese dose evaluation in global drug development: factors that generate different dosages between Japan and the United States

Drug development in Japan is shifting from a bridging strategy to a global strategy, and the number of multiregional trials in which Japan is included is increasing every year. The Japanese drug regulatory authority requires that data be collected in Japanese populations, and therefore dose-response studies of various drugs are frequently conducted in Japan. However, the current standard for adequate dose-finding processes may sometimes hinder the timely participation of Japan in these multiregional trials. We studied the development approaches and review patterns of 99 new molecular entities (NMEs) approved in 2003-2008 and have identified some common factors that result in differences in approved dosages in Japan as compared with other countries, such as dose-response study design, pharmacokinetics, and the timing of development. The findings of our research will serve as an initial information base on which to build an efficient global drug development strategy in Japan.