Earticle

Adverse drug reactions (ADR) caused by inappropriate prescription are responsible for major socioeconomic loss. Drugdrug interactions (DDI) has been recognized as a major part of ADRs and, therefore, healthcare professionals should prevent possible DDIs to minimize preventable ADRs. This study aimed to examine DDI information in drug information references and Korea Food & Drug Administration (KFDA) drug labeling information. Drug ingredients from the formulary of Health Insurance Review and Assessment Service in Korea (HIRA) were included for the study. DDI information source used for the study were Micromedex Drugdex and Drug Information Facts (DIF) with the DDI severity level of “moderate” or more. The DDI information in KFDA drug labeling were collected and compared. Drug ingredients were classified with KFDA Drug Classification and ATC Classification of WHO for the analysis. Among the total 1,355 drug ingredients satisfying inclusion criteria, 738 ingredients involved at least one DDI, which was described in Micromedex and/or DIF. Drug Ingredients of 176 involved DDI only described in KFDA drug labeling, but not Micromedex nor DIF. Drug ingredients of 35 which DDIs were described in Micromedex or DIF did not have DDI based on KFDA drug labeling. Micromedex and DIF retrieved 7,582 and 3,071 DDIs, respectively 57.6% and 58.5% of DDIs were also described in KFDA drug labeling. Central nervous system (CNS) drugs, cardiovascular system(CVS) drugs and the antiinfectives appeared to have higher frequency of DDIs among all drug classes. The highest number of DDIs with high severity level (“contraindicated” or “major”) were the DDIs of CNS drugs. The antiinfectives are the second drug group having serious DDIs. The DDI pairs of the CNS drug and the antiinfective had the highest contraindication risk (13.6%). DDI information from Micromedex and DIF were not consistent with the result that only 465 ingredients' DDIs are common in both literature (total DDI numbers were 715 vs 488, respectively). And 1,652 DDI information are common in both references among 7,582 vs 3,071 DDIs, respectively. Only 55.2% of DDI information in the database contained in the KFDA drug labeling. Prescribers and pharmacists should pay attention to the drugs for CV system, CNS and infections because of higher risk of possible DDIs compared to other drug classes. KFDA drug labeling is not likely to be recommended as a good information source for DDI due to significant inconsistency of information. Drug information providers should be aware that DDI information from different sources are not consistent and therefore multiple references should be used.

Oxaliplatin is a tolerable and effective drug of choice in the treatment of advanced or metastatic gastric cancer. However, it has many dose-limiting neurotoxicities. This study was performed to assess the incidence and types of oxaliplatin-related neurotoxicities. Sixty-four patients receiving oxaliplatin-involved regimen as salvage therapy on metastatic gastric cancer or as the first-line therapy on advanced gastric cancer were evaluated during the period between September 1, 2006 and February 29, 2008. The patients were treated with oxaliplatin 100 mg/m2 and leucovorin 100 mg/m2 simultaneously as 2-hour-lasting infusion on Day-1 followed by 5-FU 1200 mg/m2 as a 22-hour-lasting continuous infusion both on Day-1 and Day-2 by every other week. We developed questionnaires to evaluate patient-recognized neurotoxic symptoms rather than the observer-described events. Surveys were completed at bedside or via telephone interview. Acute and chronic neurotoxicities were graded according to the National Cancer Institute Common Toxicity Criteria (NCI-CTC, version 3) as well as the Oxaliplatin-specific Neurotoxicity Scale. The Grade-3 neuropathy was reported in 19% of the patients (n=12) and grade-1/2 neuropathy occurred in 70% (n=45). The most common symptom was cold-related dysesthesia (83%) regarded as nociperception by the patients. Some patients (19%) experienced functional impairment affecting activities of daily living such as writing, buttoning, and walking. Even though 74% of the patients (42/57) were prescribed with gabapentin to reduce these peripheral symptoms, it did not appear to derive any benefit from this medication. It is suggested that notify the patients about their oxaliplatin-associated, debilitating symptoms, and educate them any self-care strategy at the initiating phase of the chemotherapy. Moreover, it needs to design the intervention studies regarding the prevention and management of the peripheral neuropathy.

The aim of this study was to evaluate the pharmacokinetic parameters of two risedronate preparations. The clinical assessment was conducted on 46 healthy volunteers who received one tablet (Risedronate sodium 35 mg/tablet) in the fasting state, in a randomized balanced 2×2 cross-over study design. After dosing of one tablet containing 35 mg risedronate sodium, blood samples were collected serially for a period of 48 hours. Plasma was analyzed for risedronate by using LC/MS/MS assay method. The analysis system was validated in specificity, accuracy, precision, and linearity. AUCt, (the area under the plasma concentration-time curve from the zero-time to 48 hr) was calculated through the trapezoidal rule. Cmax (maximum plasma drug concentration) were compiled from the plasma risedronate concentrationtime data of each volunteer. No significant sequence effect was found for the pharmacokinetic parameters indicating that the cross-over design was properly performed. The 90 % - Confidence intervals of the AUCt ratio and the Cmax were from log 0.8752 to log 1.1888 and log 0.8457 to log 1.1478, respectively. These values were within the acceptable intervals between 0.80 and 1.25. Therefore, this study demonstrated that no statistically significant difference was identified with respect to the rate and extent of absorption.

The aim of this study was to investigate the effect of simvastatin on the pharmacokinetics of nicardipine in rats. Pharmacokinetic parameters of nicardipine were determined after an oral administration of nicardipine (12 mg/kg) to rats coadministered with simvastatin (0.3 and 1.0 mg/kg). Compared with the control (given nicardipine alone), coadministration of simvastatin (1.0 mg/kg) significantly (p<0.05) increased the area under the plasma concentration (AUC) andpeak plasma concentration (Cmax) of nicardipine. The relative bioavailability (RB%) of nicardipine increased from 1.19-to 1.48-fold. However there were no significant changes in tmax, and t1/2 of nicardipine. The enhanced oral bioavailability of nicardipine might be due to an inbition of cytochrom P450 3A mediated-metabolism of nicardipine in the intestine and in the liver by simvastatin. Based on these results, the concurrent use of simvastatin significantly enhanced the oral exposure of nicardipine in rats. The dosage regimen of nicardipine should be taken into consideration for potential drug interaction when combined with simvastatin in clinics.

The purpose of this study was to evaluate barriers to pharmacists’ routine work in community setting. A survey was given to 281 pharmacists who enrolled in 16-week clinical pharmacy educating program in continuous education center for advanced pharmacy at Seoul National University. Three main questions that pharmacists were asked to answer were: (1) difficulties on dispensing prescription, (2) difficulties on communicating with doctors, (3) most difficult disease on patients counseling. The response rates for the survey were more than 60 % for each three questions (62.63 %, 63.7 %, and 64.41 %, respectively). The top three barriers to dispensing prescription were lack of professional knowledge about medications, prescription error and its solving ability and patient counseling. The top three barriers to communicating with doctors were lacking of opportunity to discuss about patients’ medication due to unavailability of doctors, doctors’ attitude using authoritative manner, and a pharmacist’s lack of knowledge. The top 4 most difficult diseases on patients counseling were cardiovascular disorders, dermatologic disorders, endocrinologic disorders, and psychiatric disorders.

토브라마이신은 그람음성균 감염에 사용하는 아미노글리코사이드계 항생제로 이독성 및 신독성 등의 부작용과 큰 개인차로 혈중농도 모니터를 통한 투여계획이 필요한 약물이다. 본 연구에서는 16명의 위암환자에서 비선형 최소자승회귀분석과 베이시안 분석에 의한 토브라마이신의 약물동태에 분석오차의 영향에 대하여 연구하였다. 약물투여는 토브라마이신 1-2 mg/kg을 30분에 걸쳐 8시간 간격으로 등속 주입하였으며, 혈액 채취는 정상상태에 도달되었다고 판단되는 첫 약물투여 72시간 후에, 약물 주입 5분전과 주입이 끝난 뒤 30분과 2시간에서 세차례 채취하였다. 혈청중 약물농도는 형광편광면역법으로 측정 하였다. 분석오차를 위해 0, 1, 2, 4, 8 및 12 μg/mL에 해당하는 토브라마이신 혈중농도(C)을 네차례 측정하여 각 혈중농도의 표준편차 (SD)을 구하였다. 토브라마이신 분석오차를 구하기 위한 다항식이 SD = 0.0224+0.0540C+0.00173C2, R2 = 0.935이었다. 이 식에서 구한 SD 값으로 분석시 가중치를 주었을 때, 비선형 최소자승 회귀분석에 의한 토브라마이신의 약물동태학적 파라메타 (Vd, Kel, Kslpoe, t1/2)에 유의성있는 영향을 주었으나, 베이시안 분석에 의한 토브라마이신의 약물동태학적 파라메타에는 영향이 없었다. 이 다항식으로 부터 구한 분석오차를 토브라마이신의 비선형 최소자승 회귀분석을 이용한 약물동태 연구 및 파라메타 분석에 적용하여 좀 더 정확한 투여용량을 결정할 수 있으며, 더 나아가 토브라마이신 약물동태 시뮬레이션 연구에 응용할 수 있다.

Highly variable drugs (within-subject variability greater than 30%) have been difficult to meet current regulatory acceptance criteria using a reasonable number of study subjects. In this study, we reviewed previous studies presenting alternative approaches for bioequivalence evaluation of highly variable drugs, and focused on an approach for widening the bioequivalence acceptance limits using within-subject variability. We discussed the suggested five solutions for highly variable drug including the deletion of Cmax of the bioequivalence criteria, direct expansion of bioequivalence limit, multiple dose studies in steady state, bioequivalence assessment on the metabolite, add-on study, and widening the bioequivalence acceptance limits based on reference variability. The methods for widening of bioequivalence limits based on reference variability are scaled average bioequivalence containing within-subject variability on reference drug (σWR), population bioequivalence derived from total variability on reference drug (σTR) and test drug (σTT), and individual bioequivalence derived from subject by formulation interaction variability (σD) and within subject variability on reference drug (σWR) and test drug (σTR). To apply these methods, the switching variability (σ0) will have to be set by the regulatory authorities. The proposals of bioequivalence evaluation approach for the highly variable in Korea are presented for both of new drug and reevaluation drug.

The study was designed to compare the rate and extent of absorption of two enalapril tablets (10 mg), which has been widely used for the treatment of hypertension. This bioequivalence study was conducted using a standard preparation as reference and a generic as test in 24 male healthy volunteers. After an overnight fast, a single dose of the test or reference drugs were given with a washout period of 7 days. Heparinized blood samples were serially collected up to 10 hr. Plasma enalapril concentrations were quantified using a validated LC-MS/MS method. The data obtained for each subject was evaluated for Cmax and AUC10hr with respect to 90% confidence interval for log-transformed data. The 90% confidence intervals were log(0.9384)~log(1.1160) for AUC10hr and log(0.9482)~log(1.1474) for Cmax. Thus, we concluded that the test and reference formulation are bioequivalent in terms of rate and extent of absorption.

Disposal infusion device is known to be useful for chemotherapy. Anti-cancer drug can be released by the force of carbon dioxide or balloon. In this study, we compared the Anapa® (LC0020) with B Company (LV2 ml) in terms of infusion rate and stability. Infusion rate was determined every six minute using software, MSI08IH. Stability of 5-fluorouracil was examined periodically using a High Performance Liquid Chromatography. Infusion rates of gas-derived Anapa device were 2.29, 1.86, 1.98 ml/hr and those of balloon-derived B Company device were 1.71, 1.58, 1.37 ml/ min. There were no significant differences in stability of 5-fluorouracil between Anapa® and B Company devices. In summary, gas-derived Anapa® device is thought to be comparable or superior to balloon-derived B Company device as far as infusion rate and stability are concerned. We expect that Anapa® as a home infusion device can be employed to improve a quality of life and compliance of cancer patients.