Drug safety on trial. Last year's withdrawal of the anti-arthritis drug Vioxx triggered a debate about how to better monitor drug safety even after approval

Pharmacometrics: A New Era of Pharmacotherapy and Drug Development in Low- and Middle-Income Countries

Pharmacotherapy, in many cases, is practiced at a suboptimal level of performance in low- and middle-income countries (LMICs) although stupendous amounts of data are available regularly. The process of drug development is time-consuming, costly, and is also associated with loads of hurdles related to the safety concerns of the compounds. This review was conducted with the objective to emphasize the role of pharmacometrics in pharmacotherapy and the drug development process in LMICs for rational drug therapy. Pharmacometrics is widely applied for the rational clinical pharmacokinetic (PK) practice through the population pharmacokinetic (popPK) modeling and physiologically based pharmacokinetic (PBPK) modeling approach. The scope of pharmacometrics practice is getting wider day by day with the untiring efforts of pharmacometricians. The basis for pharmacometrics analysis is the computer-based modeling and simulation of pharmacokinetics/pharmacodynamics (PK/PD) data supplemented by characterization of important aspects of drug safety and efficacy. Pharmacometrics can be considered an invaluable tool not only for new drug development with maximum safety and efficacy but also for dose optimization in clinical settings. Due to the convenience of using sparse and routine patient data, a significant advantage exists in this regard for LMICs which would otherwise lag behind in clinical trials.

Incorporating patient preferences and burden-of-disease in evaluating ALS drug candidate AMX0035: a Bayesian decision analysis perspective

OBJECTIVE

Provide US FDA and amyotrophic lateral sclerosis (ALS) society with a systematic, transparent, and quantitative framework to evaluate the efficacy of the ALS therapeutic candidate AMX0035 in its phase 2 trial, which showed statistically significant effects (p-value 3%) in slowing the rate of ALS progression on a relatively small sample size of 137 patients.

METHODS

We apply Bayesian decision analysis (BDA) to determine the optimal type I error rate (p-value) under which the clinical evidence of AMX0035 supports FDA approval. Using rigorous estimates of ALS disease burden, our BDA framework strikes the optimal balance between FDA's need to limit adverse effects (type I error) and patients' need for expedited access to a potentially effective therapy (type II error). We apply BDA to evaluate long-term patient survival based on clinical evidence from AMX0035 and Riluzole.

RESULTS

The BDA-optimal type I error for approving AMX0035 is higher than the 3% p-value reported in the phase 2 trial if the probability of the therapy being effective is at least 30%. Assuming a 50% probability of efficacy and a signal-to-noise ratio of treatment effect between 25% and 50% (benchmark: 33%), the optimal type I error rate ranges from 2.6% to 26.3% (benchmark: 15.4%). The BDA-optimal type I error rate is robust to perturbations in most assumptions except for a probability of efficacy below 5%.

CONCLUSION

BDA provides a useful framework to incorporate subjective perspectives of ALS patients and objective burden-of-disease metrics to evaluate the therapeutic effects of AMX0035 in its phase 2 trial.

Isatin-3-acylhydrazones with enhanced lipophilicity: synthesis, antimicrobial activity evaluation and the influence on hemostasis system

Water-soluble trialkylammonium isatin-3-hydrazone derivatives bearing hydroxybenzyl substituent were easily synthesized with high yields. XRD studies confirmed the presence of these compounds as trans-( Z )-isomers in a crystal. It was shown that an increase in the lipophilicity of the cationic center leads to an increase in activity against Gram-positive bacteria Staphylococcus aureus and Bacillus cereus, including methicillin-resistant (MRSA) strains. The MIC values of the leading compounds turned out to be 2-100 times higher than the MIC of norfloxacin against the MRSA strains in the absence of hemo- and cytotoxicity. Antiaggregation and anticoagulation properties were in vitro better than for acetylsalicylic acid and sodium heparin drugs. It has been shown by UV spectroscopy and fluorescence microscopy that the mechanism of antimicrobial action of new acylhydrazones is associated with their ability to destroy the bacterial cell membrane.

Elucidating the anticancer activities of guanidinium-functionalized amphiphilic random copolymers by varying the structure and composition in the hydrophobic monomer

Rationale: Use of traditional anticancer chemotherapeutics has been hindered by the multifactorial nature of multi-drug resistance (MDR) development and metastasis. Recently, cationic polycarbonates were reported as novel unconventional anticancer agents that mitigated MDR and inhibited metastasis. The aim of this study is to explore structure-anticancer activity relationship. Specifically, a series of cationic guanidinium-based random copolymers of varying hydrophobicity was synthesized with a narrow polydispersity (Ð = 1.12-1.27) via organocatalytic ring-opening polymerization (OROP) of functional cyclic carbonate monomers, and evaluated for anticancer activity, killing kinetics, degradability and functional mechanism. Methods: Linear, branched and aromatic hydrophobic side chain units, such as ethyl, benzyl, butyl, isobutyl and hexyl moieties were explored as comonomer units for modulating anticancer activity. As hydrophobicity/hydrophilicity balance of the polymers determines their anticancer efficacy, the feed ratio between the two monomers was varied to tune their hydrophobicity. Results: Notably, incorporating the hexyl moiety greatly enhanced anticancer efficiency and killing kinetics on cancer cells. Degradation studies showed that the polymers degraded completely within 4-6 days. Flow cytometry and lactate dehydrogenase (LDH) release analyses demonstrated that anticancer mechanism of the copolymers containing a hydrophobic co-monomer was concentration dependent, apoptosis at IC50, and both apoptosis and necrosis at 2 × IC50. In contrast, the homopolymer without a hydrophobic comonomer killed cancer cells predominantly via apoptotic mechanism. Conclusion: The hydrophobicity of the polymers played an important role in anticancer efficacy, killing kinetics and anticancer mechanism. This study provides valuable insights into designing novel anticancer agents utilizing polymers.

The mixed randomized trial: combining randomized, pragmatic and observational clinical trial designs

Clinical trial designs often fail to deliver data that jointly satisfy evolving demands of both regulatory and reimbursement authorities. We propose a new multi-tiered trial design to integrate efficacy and effectiveness, and address the evolving needs of authorities. The mixed randomized trial allocates patients first to trial arm – randomized controlled, pragmatic (randomized) or observational – and then to treatment group – experimental, placebo, active comparator, best available therapy or standard of care. Trial arms may be staggered over time to reflect the current state of randomized and non-randomized data of the experimental drug, and thereby still prioritize safety. At the same time, the mixed randomized trial allows for the collection of real-world data in a randomized setting, and thereby reduces selection bias.

Delays in the post-marketing withdrawal of drugs to which deaths have been attributed: a systematic investigation and analysis

BACKGROUND

Post-marketing withdrawal of medicinal products because of deaths can be occasioned by evidence obtained from case reports, observational studies, randomized trials, or systematic reviews. There have been no studies of the pattern of withdrawals of medicinal products to which deaths have been specifically attributed and the evidence that affects such decisions. Our objectives were to identify medicinal products that were withdrawn after marketing in association with deaths, to search for the evidence on which withdrawal decisions were based, and to analyse the delays involved and the worldwide patterns of withdrawal.

METHODS

We searched the World Health Organization's Consolidated List of [Medicinal] Products, drug regulatory authorities' websites, PubMed, Google Scholar, and textbooks on adverse drug reactions. We included medicinal products for which death was specifically mentioned as a reason for withdrawal from the market. Non-human medicines, herbal products, and non-prescription medicines were excluded. One reviewer extracted the data and a second reviewer verified them independently.

RESULTS

We found 95 drugs for which death was documented as a reason for withdrawal between 1950 and 2013. All were withdrawn in at least one country, but at least 16 remained on the market in some countries. Withdrawals were more common in European countries; few were recorded in Africa (5.3%). The more recent the launch date, the sooner deaths were reported. However, in 47% of cases more than 2 years elapsed between the first report of a death and withdrawal of the drug, and the interval between the first report of a death attributed to a medicinal product and eventual withdrawal of the product has not improved over the last 60 years.

CONCLUSIONS

These results suggest that some deaths associated with these products could have been avoided. Manufacturers and regulatory authorities should expedite investigations when deaths are reported as suspected adverse drug reactions and consider early suspensions. Increased transparency in the publication of clinical trials data and improved international co-ordination could shorten the delays in withdrawing dangerous medicinal products after reports of deaths and obviate discrepancies in drug withdrawals in different countries.

Current practices in preclinical drug development: gaps in hemostasis testing to assess risk of thromboembolic injury

The Health and Environmental Sciences Institute Cardiac Biomarkers Working Group surveyed the pharmaceutical development community to investigate practices in assessing hemostasis, including detection of hypocoagulable and hypercoagulable states. Scientists involved in discovery, preclinical, and clinical research were queried on laboratory evaluation of endothelium, platelets, coagulation, and fibrinolysis during safety assessment studies. Results indicated that laboratory assessment of hemostasis is inconsistent among institutions and not harmonized between preclinical and clinical studies. Hemostasis testing in preclinical drug safety studies primarily focuses on the risk of bleeding, whereas the clinical complication of thrombosis is seldom assessed. Our results reveal the need for broader utilization of biomarkers to detect altered hemostasis (e.g., endothelial and platelet activation) to improve preclinical safety assessments early in the drug development process. Survey respondents indicated a critical lack of validated markers of hypercoagulability and subclinical thrombosis in animal testing. Additional obstacles included limited blood volume, lack of cross-reacting antibodies for hemostasis testing in laboratory species, restricted availability of specialized hemostasis analyzers, and few centers of expertise in animal hemostasis testing. Establishment of translatable biomarkers of prothrombotic states in multiple species and strategic implementation of testing on an industry-wide basis are needed to better avert untoward drug complications in patient populations.

Blood pressure control rates with an antihypertensive regimen including trandolapril in a Canadian usual-care setting

INTRODUCTION

The aim of the study was to assess the effects on blood pressure (BP) levels and control rates in hypertensive subjects receiving trandolapril as monotherapy or as part of an antihypertensive regimen in everyday Canadian clinical practice.

METHODS

The MAVIKtory study was a multicenter, single-arm observational study in 601 primary-care centers in Canada. Diabetic and nondiabetic subjects were included, who were treated with trandolapril for hypertension in accordance with usual practices and national guidelines. Subjects received trandolapril as a new prescription, alone, or in combination with prior therapy. Treatment regimens were at the discretions of the treating physicians. Subjects were followed for 6 months. The primary outcomes measures were the percentage of subjects reaching BP targets set by their physicians after 6 months of therapy, and the percentage of subjects reaching the guidelines targets (systolic blood pressure [SBP]/diastolic blood pressure [DBP] < 140/90 mm Hg) after 6 months as assessed by their physicians. Other outcomes were the percentage of diabetic subjects reaching BP targets, and tolerability.

RESULTS

A total of 8787 subjects were enrolled and included in the intention-to-treat population. Starting doses of trandolapril were 1 or 2 mg in the majority of subjects and remained unchanged in 51.9% of the population at 6 months. The target of < 140/90 (< 130/80) mm Hg was reached by 67.3% of the population. The lower mean physician-set target of 133.4/83.3 mm Hg for nondiabetic subjects and 128.6/79.3 mm Hg for diabetic subjects was reached by 52.2%. Mean reductions from baseline to month 6 were 19.4 mm Hg (95% CI: [-19.9 to -19.0]) in SBP, and 10.1 mm Hg (95% CI: [-10.4 to -9.8]) in DBP. Cough was the most commonly reported adverse event, reported in 4.2% of all subjects.

CONCLUSION

Trandolapril demonstrated a favorable safety and effectiveness profile. SBP reductions of approximately 20 mm Hg and control rates > 65% could be achieved over 6 months.

The value of observational cohort studies for cancer drugs

Randomized controlled trials - the gold standard for clinical drug evaluation -can't always predict adverse events in real-world settings. For the new cancer therapies, observational cohort studies (OCSs) can help evaluate their effects in broader populations and provide valuable information for future clinical trials.