The third equation on page 44 should be corrected.

We developed a high-performance liquid chromatographic procedure for the determination of 4-(4-chlorophenyl)-4-hydroxypiperidine (CPHP), a toxic metabolite of haloperidol, in human. Chromatographic analysis was performed on a reverse-phase C₁₈ column with a mobile phase containing 50 mM potassium phosphate buffer/acetonitrile (75:25, vol/vol) using UV detection with a wavelength of 220 nm. The limits of detection for CPHP were 1 ng/ml in urine and the assay was linear over the concentration range of 2-500 ng/ml for urine. This analytical method was applied to measure CPHP in human. Nineteen healthy subjects were enrolled and all subjects received a single oral dose of 5 mg haloperidol following a treatment of placebo or itraconazole at 200 mg/day for 10 days in a randomized crossover manner. CPHP was detected in urine samples and average recovered amount of CPHP was 81.31 µg/24 hr in the placebo phase and it was significantly reduced to 30.34 µg/24 hr after itraconazole treatment. The finding provides in vivo evidence that CPHP is an in vivo metabolite of haloperidol in human and its formation is mediated by CYP3A4.
Chromatography, High Pressure Liquid ; Cytochrome P-450 CYP3A ; Haloperidol* ; Healthy Volunteers ; Humans* ; Itraconazole ; Limit of Detection ; Methods* ; Potassium

Antiepileptic drugs (AEDs) have been known to induce cutaneous adverse drug reaction (cADR), ranging from a mild maculopapular eruption (MPE) to potentially life-threatening cADRs such as Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Despite studies examining mechanisms associated with human leukocyte antigen (HLA), the association between lamotrigine (LTG)-induced cADR and HLA alleles still has room to investigate. We investigated HLA-A,-B, and -C alleles in LTG-induced cADR. The medical records of four patients with LTG-induced cADR were retrospectively reviewed. All patients were treated with LTG for epilepsy. All recovered from cADR after stopping LTG treatment and receiving intensive care. HLA-A, -B, and -C genotyping was performed in all four patients using a PCR-sequence-based typing (SBT) method. Two patients had SJS, and the other two had MPE due to LTG. The range of latency to cADR after the initial LTG dose was 19–42 days. Two patients experienced cross-reactivity with other aromatic or new AEDs. Expression of the HLA-A*24:02/B*51:01 haplotype was detected in three (75%) patients with LTG-induced cADR. The other patient carried homozygous HLA-B*58:01 alleles. The results suggest that Korean individuals with the HLA-A*24:02/B*51:01 haplotype may be susceptible to LTG-induced cADR. Further investigations are necessary to confirm these findings.
Alleles ; Anticonvulsants ; Critical Care ; Drug-Related Side Effects and Adverse Reactions* ; Epilepsy ; Haplotypes* ; HLA-A Antigens ; Humans ; Leukocytes ; Medical Records ; Methods ; Retrospective Studies ; Stevens-Johnson Syndrome

Alpha-lipoic acid, a physiological form of thioctic acid, is a strong antioxidant that relieves diabetic neuropathic symptoms. R(+)-α-lipoic acid shows superior antioxidative effects to its racemate. We compared the pharmacokinetics (PKs) and tolerability of R(+)- and S(-)-α-lipoic acid after a single oral dose of R(+)-α-lipoic acid, Dexid®, and its racemate, thioctic acid in healthy male subjects. We used an open-label, randomized, single-dose, three-treatment, parallel study design to compare the PK exposure of the active form, R(+)-α-lipoic acid. Thirty subjects completed the study with no clinically relevant safety issues. The peak concentrations (C(max), mean±SD) of R(+)-α-lipoic acid after doses of R(+)-α-lipoic acid 200 mg, 300 mg and thioctic acid 600 mg were 4186.8±1956.7, 6985.6±3775.8 and 6498.4±3575.6 µg/L, respectively, and the areas under the plasma concentration-time curve from 0 to the last measurable concentration (AUC(last)) were 1893.6±759.4, 3575.2±1149.2 and 3790.0±1623.0 µg·h⁻¹·L⁻¹, respectively. The geometric mean ratio and 90% confidence intervals of R(+)-α-lipoic acid 200 mg to thioctic acid 600 mg for the C(max) and AUC(last) were 0.71 (0.43–1.15) and 0.51 (0.37–0.70), respectively. The corresponding R(+)-α-lipoic acid 300 mg to thioctic acid 600 mg values were 1.11 (0.68-1.80) and 0.97 (0.71-1.34), respectively. In conclusion, R(+)-α-lipoic acid 300 mg showed PK characteristics similar to those of thioctic acid 600 mg and both formulations were well tolerated.
Humans ; Male* ; Pharmacokinetics ; Plasma ; Thioctic Acid*

Hyperlipidemia and hypertension are among the major risk factors for cardiovascular disease (CVD) and they often co-exist within a single patient. Recently, many studies published results regarding the potential role of statins in decreasing blood pressure (BP) however there is still a controversy over the efficacy of statin therapy on BP. This study aimed to investigate the potential role of rosuvastatin in BP lowering properties in Korean population. Data were taken from three randomized, multiple-dose cross over studies for rosuvastatin, angiotensin II receptor blocker (ARB) and metformin monotherapies and the combined therapy of rosuvastatin and ARB, in total of 91 healthy male normotensive subjects. Measurements of systolic blood pressure (SBP), diastolic blood pressure (DBP) at the baseline before treatment begins and for 24 hours after the last dose were used in the analysis. The analysis variables used were (i) the mean change in steady-state BP from the baseline, symbolized as ΔBP, and (ii) the difference in ΔBP between the ARB monotherapy and the combined therapy, symbolized as ΔBP,d. The ΔBP and ΔBP,d for SBP from each study varied in -0.1 ~ -1.3 mmHg and 1.2 ~ 1.6 mmHg, respectively, and were not significantly different from zero. The ΔBP and ΔBP,d for DBP from each study varied in -2.8 ~ -1.4 mmHg and -2.9 ~ -1.8, respectively, which were statistically significant for ΔBP (p < 0.05) but was not for ΔBP,d (p > 0.05). These results indicated that the rosuvastatin monotherapy may produce small blood pressure lowing effect in DBP.
Blood Pressure* ; Cardiovascular Diseases ; Cross-Over Studies ; Humans ; Hydroxymethylglutaryl-CoA Reductase Inhibitors* ; Hyperlipidemias ; Hypertension ; Male ; Metformin ; Receptors, Angiotensin ; Risk Factors ; Rosuvastatin Calcium*

Pharmacokinetic blood sampling is a prerequisite for successful early clinical trials. It is essential to take samples at the precise designated times to ensure the reliability of the clinical trial data; however, investigators have encountered difficulties in conducting procedures with limited manpower. We have recently developed automated schedule broadcast software (Rooibos™) to manage the precise scheduling of procedures for clinical trial centers. Rooibos™ is platform independent because it is programmed in the Java language. It generates scheduled times based on a reference time. It alarms at the scheduled times and pages subjects and alerts staff to prepare for the upcoming procedures. Rooibos™ can also group subjects when multiple clinical trials are conducted simultaneously in one or more clinical trial wards. This software may be applied to any study involving procedures that must be performed at designated times.
Appointments and Schedules* ; Humans ; Indonesia ; Pharmacology, Clinical* ; Research Personnel

Vancomycin is a widely used glycopeptide antibiotic that requires therapeutic drug monitoring (TDM) owing to its narrow therapeutic window. It is primarily eliminated by renal excretion; thus, estimating the renal function of a patient is vital in the TDM of vancomycin. In patients with Duchenne muscular dystrophy (DMD), it is difficult to estimate the glomerular filtration rate using the serum creatinine level owing to the pathophysiological nature of the disease. Here, we report a case of a patient in whom TDM of vancomycin was performed, and explore the appropriate methods for evaluating renal function in patients with DMD based on serum levels of creatinine and cystatin C.
Creatinine ; Cystatin C ; Drug Monitoring* ; Glomerular Filtration Rate ; Humans ; Muscular Dystrophy, Duchenne* ; Renal Elimination ; Vancomycin*

The importance of precise information and knowledge on the initial estimates (IEs) in modeling has not been paid its due attention so far. By focusing on the IE, this tutorial may serve as a practical guide for beginners in pharmacometrics. A 'good' set of IEs rather than arbitrary values is required because the IEs where NONMEM kicks off its estimation may influence the subsequent objective function minimization. To provide NONMEM with acceptable IEs, modelers should understand the exact meaning of THETA, OMEGA and SIGMA based on physiology. In practice, problems related to the value of the IE are more likely to occur for THETAs rather than the random-effect terms. Because it is almost impossible for a modeler to give a precise IE for OMEGAs at the beginning, it may be a good practice to start at relatively small IEs for them. NONMEM may fail to converge when too small IEs are provided for residual error parameters; thus, it is recommended to give sufficiently large values for them. The understandings on the roles, meanings and implications of IEs even help modelers in troubleshooting situations which frequently occur over the whole modeling process.
Physiology

This tutorial examines the relationship between CL, F, and hepatic blood flow (Q(H)) quantitatively at oral and i.v. administration as an answer to the quiz set for KSCPT members. In case of oral dosing, when hepatic blood flow increases, the hepatic clearance (CL) and bioavailability (F) increases in high-extraction ratio drugs according to the well-stirred model equations for hepatic clearance: CL(H) = Q(H)·ER = Q(H)·f(u)·CL(int)/(Q(H)+f(u)·CL(int)) and F = 1 - ER Despite such a clear relationship, many students may feel it rather paradoxical that the increased CL (thus decreasing the AUC) causes increased F and thus the AUC (F·Dose/CLH) remains unchanged. This tutorial clarifies that the degree to which CL increase fails to match that of the Q(H) increase, and thus the decreased ER (= CL/Q(H)) that results in the increased F. Contemplating this simple, but seemingly paradoxical phenomenon may help students gain a deeper understanding of the first-pass effect.
Area Under Curve ; Biological Availability ; Humans

Co-administration of tadalafil and tamsulosin HCl in patients with benign prostate hyperplasia and erectile dysfunction is increasing in clinical settings. Development of fixed-dose combination (FDC) of tadalafil and tamsulosin HCl could contribute to improving patients' adherence and treatment efficacy. We evaluated the pharmacokinetics and safety profiles of a newly developed fixed-dose combination capsule of tadalafil 5 mg/tamsulosin HCl 0.4 mg in comparison with co-administration of each formulation in healthy volunteers under fasted and fed conditions. Two randomized, open-label, single-dose, two-way, crossover studies were completed in 29 subjects under fasted condition, and 33 subjects under fed condition. Serial blood sample collection for PK analysis was conducted up to 72 hours after dosing, and PK parameters were calculated using non-compartmental analysis. Geometric mean ratios and 90% confidence intervals of the C(max) and AUC(last) were used to evaluate comparative bioavailability. In both fasted and fed condition studies, the bioequivalence was established. The most common adverse drug reactions were orthostatic hypotension and headache with no statistical difference between treatment groups. All subjects with orthostatic hypotension recovered at follow-up test. Although changes in vital signs from baseline were statistically significant, there were no subjects with systolic blood pressure < 90 mmHg and there were no clinically meaningful signs or symptoms associated. FDC of tadalafil and tamsulosin HCl can be an alternative to co-administration of individual drugs for providing better compliance. Changes in blood pressure should be kept in mind when tadalafil and tamsulosin HCl are co-administered in clinical settings.
Biological Availability ; Blood Pressure ; Compliance ; Cross-Over Studies ; Drug-Related Side Effects and Adverse Reactions ; Erectile Dysfunction ; Follow-Up Studies ; Headache ; Healthy Volunteers* ; Humans ; Hyperplasia ; Hypotension, Orthostatic ; Male ; Pharmacokinetics* ; Prostate ; Tadalafil ; Therapeutic Equivalency ; Treatment Outcome ; Vital Signs