Evaluation of rifampicin bioequivalence in fixed-dose combinations using the WHO/IUATLD recommended protocol.

For an accurate assessment of rifampicin bioequivalence from fixed-dose combinations (FDCs), and to reduce the time and cost constraints associated with bioequivalence studies, the World Health Organization and the International Union Against Tuberculosis and Lung Disease have developed a simplified screening protocol. This study was undertaken with the objective of testing the applicability of this protocol for all types of FDCs. Data were obtained for volunteers common to three studies, and pharmacokinetic parameters were evaluated by different statistical tests. From the results, it has been demonstrated that the simplified screening protocol is suitable for evaluating the bioequivalence of rifampicin in all the types of FDCs available on the market.     

Establishment of a reference formulation for bioequivalence assessment of rifampicin-containing FDCs: an essential step towards improving tuberculosis treatment.

SETTING: Selection of a reference product for bioequivalence studies of rifampicin (RMP) in prequalifying fixed-dose combinations (FDC) for worldwide distribution through the WHO is critical. OBJECTIVE: To investigate the feasibility of establishing FDC formulations as reference products for bioequivalence studies of RMP in prequalification programmes. DESIGN: A biostudy was conducted as an open, two-period randomised cross-over trial. Two three-drug FDCs containing RMP, isoniazid and ethambutol hydrochloride were administered to a group of 22 volunteers with a wash-out period of 1 week. Plasma samples were collected and analysed for the concentration of RMP and desacetyl-RMP, a major active metabolite of RMP, up to 24 h. Pharmacokinetic parameters of RMP were calculated: Cmax, AUC0-24, Tmax, kel and absorption efficiencies. RESULTS: No significant difference was observed between the administered formulations with respect to the major pharmacokinetic parameters Cmax, Tmax and AUC0-24 when evaluated by parametric (two-way ANOVA) and non-parametric (Hauschke's analysis) statistical analysis. The concentration of RMP falls within the reported acceptable therapeutic range. CONCLUSION: FDCs can be developed as a reference product for bioequivalence studies.     

Comparative bioequivalence study of rifampicin and isoniazid combinations in healthy volunteers.

OBJECTIVE: To assess the bioavailability of rifampicin (RMP) in three brands of combination formulations of anti-tuberculosis drugs. DESIGN: A three-way double-blind, cross-over bioavailability study of RMP and isoniazid (INH), consisting of a comparison of a two-drug combination of tablets of RMP and INH each separately (reference brand R) and a tablet of RMP + INH (brand N), and a capsule of RMP + INH (brand L) was carried out in 12 healthy male volunteers. Coded plasma samples were analysed for levels of RMP as well as INH and acetylisoniazid (ACINH) by two high performance liquid chromatography (HPLC) methods. RESULTS: The mean values of RMP in brand N (Cmax 6.49+/-0.52 microg/mL, Tmax 2.33+/-0.18 h, AUC(0-24h) 39.83+/-3.44 microg/mL.h) were comparable with those obtained with brand R (Cmax 5.22+/-0.59 microg/mL, Tmax 2.50+/-0.12 h, AUC(0-24h) 33.33+/-3.47 microg/mL.h). The mean values of RMP in brand L (Cmax 3.05+/-0.52 microg/ mL, Tmax 3.79+/-0.57 h and AUC(0-24h) 21.78+/-3.67 microg/ mL.h) were significantly different from those in brand R. Nevertheless, all of the pharmacokinetic parameters obtained for INH and ACINH in all three brands were comparable. CONCLUSION: Using brand R as a comparison, brand N was bioequivalent and brand L was not bioequivalent.     

四联抗结核固定剂量复合剂的临床疗效研究

目的研究四联抗结核固定剂量复合剂的近期疗效及安全性。方法将广东省湛江市6个县区登记的540例初治涂阳肺结核病人分为研究组和对照组,用对照研究方法对2组病例的临床症状、治疗效果和不良反应等进行对比研究。结果(1)研究组治愈率为94.4%,对照组为92.2%,2组的治愈率比较差异无统计学意义(χ2=1.071,P=0.301);(2)2组患者相关临床症状(如咳嗽、胸痛、乏力、盗汗、低热、咯血)逐渐得到改善,2组比较差异无统计学意义(P0.05);(3)2、3个月末研究组痰菌阴转率分别为90.7%、94.1%,对照组分别为89.6%,91.9%,比较差异无统计学意义(P0.05);X线胸片显示空洞愈合方面,研究组的空洞闭合率为78.2%,对照组为61.2%,研究组比对照组高。(4)研究组与对照组的不良反应发生率分别为21.5%和20.0%,比较差异无统计学意义(P0.05);强化期对照组的消化道不良反应发生率明显大于研究组(P0.05);2组血常规、肝功能异常率接近;研究组因不良反应停药率高于对照组(P0.05)。结论四联FDC与板式组合药具有同等的抗结核疗效,不良反应发生率相近,并且在治疗管理方面显示出较大的优势,建议推荐在我国结核病防治规划中应用。     

On the utility of pooling biological samples in microarray experiments

Over 15% of the data sets catalogued in the Gene Expression Omnibus Database involve RNA samples that have been pooled before hybridization. Pooling affects data quality and inference, but the exact effects are not yet known because pooling has not been systematically studied in the context of microarray experiments. Here we report on the results of an experiment designed to evaluate the utility of pooling and the impact on identifying differentially expressed genes. We find that inference for most genes is not adversely affected by pooling, and we recommend that pooling be done when fewer than three arrays are used in each condition. For larger designs, pooling does not significantly improve inferences if few subjects are pooled. The realized benefits in this case do not outweigh the price paid for loss of individual specific information. Pooling is beneficial when many subjects are pooled, provided that independent samples contribute to multiple pools.     

国产抗结核固定剂量复合剂治疗初治涂阳肺结核患者的近期疗效观察

目的探讨国产抗结核固定剂量复合剂在结核病防治规划中应用的可行性。方法采用随机分组方法将422例初治涂阳肺结核患者分为试验组(219例)和对照组(203例)。试验组在2个月强化期每日服用异福酰胺片[含利福平(R)120mg,异烟肼(H)80mg和吡嗪酰胺(Z)250mg],4个月巩固期每日服用异福片(含R300mg,H150mg);对照组采用标准6个月短程化疗方案2HRZE/4H3R3(Z为乙胺丁醇)。结果试验组和对照组年龄、性别构成,以及治疗前病情(痰菌含量、肺部病变累及范围和空洞形成)等组间差异均无显著性。采用固定剂量复合剂短程化疗2个月、3个月和6个月痰菌转阴率分别为916%、972%和977%,对照组分别为873%、975%和980%,两组疗效比较差异无显著性(χ21=205,χ22=003,χ23=004,P>005)。不良反应中皮疹发生率试验组低于对照组(Fisher精确法P=002433)。结论国产抗结核固定剂量复合剂可作为目前国家结核病防治规划使用的抗结核药的补充,供基层选用,但仍需进一步验证。     

抗结核药物固定剂量复合制剂隔日疗法临床效果分析

目的 评价国产抗结核药物固定剂量复合制剂（FDC）隔日疗法的临床应用效果,为抗结核FDC隔日疗法的推广应用提供参考依据.方法 根据两组试点市（县）地貌、人口数、总体经济状况、结核科仪器设备和工作人员水平等基本接近的原则,“抗结核药物FDC隔日疗法试点组”（简称“FDC组”）为保定市12个市（县）中纳入的初治活动性肺结核患者,共计1225例;“抗结核药物板式组合药对比观察试点组”（简称“组合药组”）为保定市另11个市（县）中纳入的初治活动性肺结核患者2328例,通过人口容量比率概率法抽取1225例患者.对两组临床治疗完成率,2、3、6个月末痰菌阴转率,疗程末X线实变阴影及空洞改变,以及不良反应等情况,用对照研究的方法进行对比观察.用统计软件包SPSS 13.0进行处理与分析,计数资料的比较采用x2检验,以P＜0.05为差异有统计学意义.结果 治疗完成率抗结核FDC组为94.53％（1158/1225）,组合药组为90.94％（1114/1225）,两组比较差异有统计学意义（x2＝11.73,P＜0.01）;2、3、6个月末痰菌阴转率抗结核FDC组分别为91.29％（262/287）、94.08％（270/287）、97.56 ％（280/287）,组合药组分别为89.05％ （244/274）、93.07％ （255/274）、96.72％（265/274）,两组比较差异均无统计学意义（x2值分别为0.79、0.24、0.36,P值均＞0.05）;FDC组疗程末X线胸片实变阴影有效吸收率及空洞改善率分别为93.06％（845/908）、89.60％（181/202）,组合药组分别为91.99％（781/849）、88.95％（169/190）,两组比较差异均无统计学意义（x2值分别为0.73、0.04,P值均＞0.05）;总不良反应发生率抗结核FDC组为21.35％（237/1110）,组合药组为22.62％（235/1039）,两组比较差异无统计学意义（x2 =0.50,P＞0.05）;实验室检测结果血常规异常、肝功能异常及肾功能异常方面,抗结核FDC组和板式组合药组相比,差异均无统计学意义（x2值分别为1.16、0.00、0.21,P值均＞0.05）.结论 国产抗结核FDC与板式组合药疗效相似,且能提高患者治疗完成率,可作为传统板式组合药的替代品.     

Position of fixed-dose combinations containing an AT(1)-receptor blocker and a thiazide diuretic

Treatment of hypertension remains a difficult task despite the availability of different types of medications lowering blood pressure by different mechanisms. In order to reach the target blood pressures recommended today combination therapy is required in most patients. The co-administration of two drugs with different impacts on the cardiovascular system markedly increases the antihypertensive effectiveness without altering adversely tolerability. Fixed low-dose combinations are becoming a valuable option not only as second-line, but also as first-line therapy. In this respect the co-administration of thiazide diuretic with an AT₁-receptor blocker is particularly appealing. The diuretic-induced decrease in total body sodium activates the renin-angiotensin system, thus rendering blood pressure maintenance angiotensin II-dependent. During blockade of the renin-angiotensin system low doses of thiazides generally suffice, allowing the prevention of undesirable metabolic effects. Also, blockade of the AT₁-receptor, particularly when angiotensin II production is enhanced in response to diuretic therapy, is expected to be beneficial, since angiotensin II seems to contribute importantly to the pathogenesis of cardiovascular and renal complications of hypertension.     

Plasma amino acid concentrations in normal adults administered aspartame in capsules or solution: lack of bioequivalence

Some clinical studies require administration of test compounds in capsules to assure that the compound cannot be distinguished from a placebo. This raises the question of whether the pharmacokinetic responses produced by capsule administration are similar to values obtained when test compounds are ingested in solution. To test this, plasma phenylalanine and aspartate concentrations were compared in ten normal subjects ingesting 3 g aspartame in solution and in capsules in a balanced Latin square design. Peak plasma phenylalanine levels were significantly higher (191 +/- 65.4 v 117 +/- 39.5 mumol/L, mean +/- SD) and were reached significantly earlier (32 +/- 15 v 123 +/- 74 minutes) when aspartame was administered in solution than when it was administered in capsules. The area under the four-hour plasma phenylalanine concentration-time curve was significantly higher (15,340 +/- 4,820 v 8,465 +/- 3,356 mumol/L X min) when aspartame was ingested in solution. Administration in solution also produced a significantly higher ratio of plasma phenylalanine concentration to the sum of the plasma concentrations of the other large neutral amino acids (0.36 +/- 0.12 v 0.23 +/- 0.06). Similarly, peak plasma aspartate concentrations were significantly higher 26.2 +/- 16.3 v 10.4 +/- 5.0 mumol/L) and were reached significantly earlier (30 +/- 14 v 106 +/- 61.3 min) when aspartame was administered in solution. The data indicate different plasma phenylalanine and aspartate pharmacokinetics between solution and capsule administration of aspartame.     

Transbronchial lung biopsy. Histopathologic and morphometric assessment of diagnostic utility.

The diagnostic utility of transbronchial lung biopsy (TBB) is partly a function of its size. However, objective parameters that reflect biopsy specimen size have not yet been well-defined. We studied clinical records and histopathologic lung tissue slides of 116 patients who underwent diagnostic TBB, aiming to define the possible significance of association between seven parameters and three categories of pathologic diagnoses. Three of the seven parameters were clinical: age, sex, and chest roentgenographic infiltrates (localized vs diffuse). The remaining four parameters were histopathologic and morphometric: total number of tissue fragments, total number of alveoli (per biopsy specimen), total tissue area (alveolated plus nonalveolated), and lung total area (alveolated tissue alone). The three categories of pathologic diagnoses were as follows: infection, tumor, and nonspecific diagnoses. The nonspecific diagnoses included diagnoses of fibrosis and/or chronic inflammation. The alveoli were microscopically counted by one of us (S.D.G.). The number of biopsy fragments, the total tissue area, and the total lung area were measured in square millimeters by a computer-assisted digitizing system using specific (Bio-Quant) software (R and M Biometrics Inc). The significance of the associations between the seven parameters and the three diagnostic categories were assessed by the chi2 test for association. Overall, the following four possible associations were found to be statistically significant: (1) age--a lower percentage of patients with infection was found among patients with increasing age (p less than 0.001); (2) roentgenographic findings--a greater percentage of tumor diagnoses were found in patients with localized infiltrates (p = 0.006); (3) number of biopsy fragments--a greater percentage of patients with diagnoses of infection was identified among patients whose biopsy specimens contained the highest number of tissue fragments (p = 0.04); and (4) number of alveoli--a greater percentage of diagnosis of infection was made in patients whose biopsy specimens contained greater than or equal to 20 alveoli (p = 0.01). Our findings support the notion that the diagnostic utility of TBB is related to its size. However, this relationship between TBB size and diagnostic utility was apparent only for diagnoses of infection and not for diagnoses of tumor. We conclude that TBB specimens containing 20 or more alveoli may (1) be declared to be adequate for diagnosis, (2) in the appropriate clinical setting, they will be most likely to yield a diagnosis of infection, and (3) the number of alveoli does not appear to be associated to the diagnosis of tumor.     

Prognostic utility of myocardial viability assessment

Myocardial viability assessment is useful in patients with severe coronary artery disease and severe left ventricular dysfunction. Whereas most studies have focused on recovery of regional function, there are emerging data on patient outcome. Review of these data suggests that patients with chronic ischemia, cardiomyopathy, and viable myocardium who are treated medically have a worse, outcome than those treated with coronary revascularization. However, there are no prospective randomized trials. We present perspectives for future studies.     

Antihypertensive effects of two fixed-dose combinations of losartan and hydrochlorothiazide versus hydrochlorothiazide monotherapy in subjects with ambulatory systolic hypertension

BACKGROUND: The efficacy of losartan (L) in combination with hydrochlorothiazide (HCTZ) has been demonstrated to reduce blood pressure. However, there are limited data on the effects of L/HCTZ combinations versus HCTZ monotherapies in reducing ambulatory systolic blood pressure. The aim of this study was to compare the effects of these treatment approaches in patients with ambulatory systolic hypertension. METHODS: Patients were randomized to receive L 50 mg (n = 60) or HCTZ 12.5 mg (n = 60) for 6 weeks. Patients were then force-titrated to L 50/HCTZ 12.5 mg and to L 100/HCTZ 25 mg or were sham-titrated to HCTZ 12.5 mg and force-titrated to HCTZ 25 mg, respectively. Clinic and 24-h ambulatory blood pressure (ABP) were measured at baseline and after each 6-week treatment period. RESULTS: We found that L 50 and HCTZ 12.5 induced significant and similar decreases in clinic and ABP. The combinations of L 50/HCTZ 12.5 and L 100/HCTZ 25 provided significantly greater decreases in clinic and ABP than did HCTZ monotherapies. The L 50/HCTZ 12.5 and L 100/HCTZ 25 combinations provided significant additional decreases in systolic/diastolic ABP during daytime (-5.3/-2.0 mm Hg; P <.001 and -5.8/-3.4 mm Hg; P <.001) and the other periods of the 24-h interval compared with the levels achieved by the previous treatment, indicating a clear dose-response relationship. However, increasing the dose of HCTZ from 12.5 mg to 25 mg was not associated with additional ABP reductions. CONCLUSIONS: Combinations of L 50/HCTZ 12.5 and L 100/HCTZ 25 provided greater reductions in clinic and ABP than HCTZ monotherapies, with a clear dose-response relationship with regard to ABP. These results support the use of ABP monitoring when assessing the efficacy of antihypertensive therapies.     

Stress Doppler echocardiography in valvular heart diseases: utility and assessment

This article is a review on the role of stress echocardiography in valvular heart diseases, describing what the validated indications are, how to perform the test and the utility of performing this examination. Most valve diseases are characteristically dynamic and this dynamic component is best appreciated by exercise Doppler echocardiography. Dobutamine stress echocardiography is also useful in patients with severe aortic stenosis and left ventricular dysfunction. The main advantage of stress echocardiography is to concomitantly allow the evaluation of symptoms, exercise capacity and the hemodynamic consequences of valve diseases, especially in patients with severe valve diseases who deny symptoms or present equivocal symptoms. It also provides important prognostic information and may help to optimize surgical timing in difficult cases. Whether these data should be integrated in the management of patients needs further validation.     

Minimum sample size and sampling time requirements for assessment of rifampicin bioequivalence from FDC formulations.

SETTING: The WHO- and IUATLD-recommended protocol for rifampicin (RMP) bioequivalence utilises 20-22 volunteers and 8 h, whereas the requirement of other regulatory authorities is 12 volunteers with a 24 h sampling schedule. Differing sampling size and time requirements may change the outcome of RMP bioequivalence. OBJECTIVE: To determine the minimal sample size and time required to assess RMP bioequivalence from FDC formulations. DESIGN: Bioequivalence studies were conducted that fulfilled the criteria of the WHO and Indian regulatory protocols. From earlier studies, retrospective pharmacokinetic evaluation, power of the test and bioequivalence limits were also calculated using 8-22 volunteers and sampling points of 8-24 h. Pharmacokinetic and statistical evaluations from three representative studies showing low, moderate and high intra-subject variability are given to determine minimum requirements for RMP bioequivalence. RESULT: It was found that a sampling schedule up to 8 h was sufficient to compare the absorption process of RMP. There was no influence of reduced sample size on bioequivalence estimates of RMP that showed low or moderate variability. However, in a study showing higher variation, a sample size of 14-16 subjects was found to be optimal. CONCLUSION: It is possible to reduce the sample size requirement for determination of RMP bioequivalence using the WHO protocol.     

The utility of microvascular perfusion assessment in heart failure: a pilot study

BACKGROUND: The evaluation of heart failure is routinely based on subjective patient symptoms and physician examination. We propose the noninvasive evaluation of microvascular and global perfusion can objectify heart failure severity and provide additional prognostic information. METHODS: A prospective, observational pilot study of patients previously stratified into New York Heart Association (NYHA) heart failure classes and who after a routine cardiology clinic evaluation were felt to be at their stable baseline state. Measurements included: thoracic impedance (Zo), hypothenar tissue hemoglobin oxygen saturation (StO2), and Zo-derived cardiac index (CI). To determine if adverse outcomes (hospitalization or death) occurred, patients or their families were contacted 6 months after enrollment and their charts reviewed. Monitor values between the NYHA classes were compared using analysis of variance. Values of those who later developed adverse outcomes were compared to patients who remained stable using a Student t-test (P < .05 considered significant). A Kaplan-Meier survival curve was used to describe the adverse outcome rate over time, and a Cox's proportional hazards model was used to relate perfusion values to adverse outcomes. RESULTS: There were no differences in CI (P = .08), Zo (P = .38), or StO2 (P = .14) found between NYHA classes (n = 46). After 6 months, 6 patients required hospitalization for heart failure and 1 died. This group had lower StO2 values compared with the stable group (P = .015). The time course of the adverse events was found not to be due to chance alone when evaluated using a Kaplan-Meier curve and the StO2 was significantly associated with time to adverse outcome (P < .05).CONCLUSIONS: Outpatient heart failure patients who later develop adverse outcomes have significantly lower StO2 values than those who remain stable. This suggests cardiac performance in stable heart failure patients may be better reflected at the microvascular level using measures such as StO2 as opposed to a global level using the physical exam or impedance cardiography. StO2 may serve as a predictor for future adverse events and as an adjunct to current evaluation techniques.     

Pharmaceutical formulation of a fixed-dose anti-tuberculosis combination.

SETTING: Department of Pharmacy and Pharmacology, University of the Witwatersrand. Despite the availability of highly effective treatment regimens for tuberculosis (TB), the cure rate still remains relatively low. This may be attributed to the high incidence of patient non-compliance, which subsequently leads to the emergence of multidrug-resistant TB (MDR-TB). To avoid the problem of further creation and propagation of MDR-TB, it may be proposed that patients should be given fixed-dose combinations of anti-tuberculosis drugs whenever self-administration is permitted. OBJECTIVE: To optimise an anti-tuberculosis extemporaneous powder formulation for suspension in order to develop a fixed combination of rifampicin, isoniazid, pyrazinamide and ethambutol hydrochloride as a powder to be reconstituted with water by the patient prior to administration. METHODS: Different suspending agents were evaluated for their influence on powder flow properties, and sediment volume on the powder blends. Sodium starch glycolate was selected as the suspending agent because of its favourable powder flow properties and sediment volume produced. The dissolution characteristics of the extemporaneous powder for suspension were also compared to the dissolution profiles of commercially available anti-tuberculosis tablet dosage forms. RESULTS: The powder for suspension for rifampicin, isoniazid, pyrazinamide and ethambutol hydrochloride all compared favourably to the dissolution rate from the commercially available tablet dosage forms.     

Switching therapy from variable-dose multiple pill to fixed-dose single-pill combinations of angiotensin II receptor blockers and thiazides for hypertension

The efficacy and tolerability of switching therapy from free combinations of angiotensin II receptor blocker (ARB) and thiazide (A/T) to a fixed-dose of losartan and hydrochlorothiazide (L/H) has not been evaluated in Japan. We examined effects of switching therapy from variable-dose multiple-pill A/T to a fixed-dose L/H on blood pressure (BP) along with medication adherence and the degree of satisfaction in 91 hypertensive outpatients (mean age, 65.2 ± 9.6 years). After 6 months, a significant BP reduction (132 ± 9/76 ± 10 vs. 126 ± 12/72 ± 11 mm Hg), along with an improvement of attaining target BP (44.0 vs. 61.5%) and that of adherence, were observed. The magnitude of BP reduction in the participants increased their degree of satisfaction more significantly than in the participants who worsened their degree of satisfaction. The estimated glomerular filtration rate and the serum uric acid (UA) level decreased slightly but significantly. The hemoglobin A1c of participants with diabetes mellitus increased slightly but significantly. In conclusion, a switch in therapy from variable-dose, multiple-pill A/T combinations to a fixed-dose, single-pill L/H was effective in decreasing BP and serum UA in Japanese clinical practice. Metabolic side effects of L/H in patients with diabetes mellitus remain to be investigated.