Comparative efficacy of esomeprazole and omeprazole: Racemate to single enantiomer switch

Sulfoxides in medicine

In the review, current status of sulfoxides on the pharmaceutical market is discussed. In the first part of the article, natural sulfoxides will be described with a special focus on sulforaphane and amanitin, a mushroom toxin which has been developed as payload in antibody drug conjugates in the possible cancer treatment. Controversies associated with the medical use of dimethylsulfoxide are briefly described in the next section. In the part devoted to PPIs, the benefits of using pure enantiomers (chiral switch) are discussed. An interesting approach, repositioning of drugs is exemplified by new possible applications of modafinil and sulindac. The review is concluded by presentation of cenicriviroc and adezmapimod, both with the status of promising drug candidates.

Evergreened drugs or evergreened profits?

BACKGROUND

Branded drugs contribute disproportionately to high prescription drug spending. Pharmaceutical companies utilize patent extension "evergreening" techniques that contribute to high drug costs.

AIMS

This article describes various patent extension techniques and analyzes the tactic of combining generic drugs with branded drugs, using metformin combinations for diabetes treatment as a case study. It examines the argument that FDCs enhance adherence and compares the cost of several branded fixed-dose combinations with the cost of their individual constituents.

MATERIALS & METHODS

We reviewed literature on patent extension techniques in both medical and marketing literature, supplemented by our own extensive files. We performed a price analysis of several branded pharmaceuticals and generically available equivalents. Prescription drug prices were determined using GoodRx.com, and prices of over-the-counter products were established based on the prices of two chain wholesalers. Patent and formulation information was taken from the FDA Orange Book: Approved Drugs with Therapeutic Equivalence Evaluations database.

RESULTS

"Evergreening" patent extension tactics include the sequential release of different formulations, minor dosing changes, and fixed-dose combinations (FDCs). A "new use" provides an opportunity for a company to re-patent, rebrand, and remarket one drug for multiple indications. It is unclear whether or not FDCs enhance adherence. Branded fixed-dose combinations generally cost far more than their individual constituents. FDCs that combine metformin with other drugs are an exception, often costing the same as the non-metformin component.

DISCUSSION

Patent extension tactics increase drug costs while providing little additional benefit to patients. Minor alterations in formulations or dosing may provide no clinical benefits. Many FDCs are expensive and fail to provide cost-justified improvements in clinical outcomes, compared to equivalent generic drugs that would save money while delivering an equal standard of care. Combining newer hypoglycemic drugs with metformin, a gold-standard, generic, inexpensive drug, does not appear to cost more than individual constituents but offers no clinical advantage over metformin alone.

CONCLUSION

Evergreening tactics should be reined in, as they represent significant cost to the healthcare system and to patients. Physicians and other prescribers should avoid prescribing FDCs, or slightly tweaked "new" drugs. Patented drug combinations generate profit without innovation.

Enantioselective recognition of esomeprazole with a molecularly imprinted sol-gel-based electrochemical sensor

A simple, selective, and accurate electrochemical chiral sensor based on molecularly imprinted polymer (MIP) has been developed for sensitive and selective detection of esomeprazole (ESOM). For this purpose, the porous MIP sensor was prepared using tetraethyl orthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) in the presence of β-cyclodextrin (β-CD) as a chiral recognizing element on a glassy carbon electrode (GCE). The changes in the MIP-layer related to removal and rebinding of the target ESOM were performed via differential pulse voltammetry (DPV) and cyclic voltammetry (CV) by using [Fe(CN)₆]^3-/4- as the redox probe. The structures of the developed sensor surface were characterized by using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical impedance spectroscopy (EIS) was also utilized for a complementary electrochemical characterization. The calibration curve was obtained in the range 1.0 × 10^-14-2.0 × 10^-13 M with a limit of detection (LOD) of 1.9 × 10^-15 M. The developed method has improved the accessibility of binding sites by producing the porous material via hydrolysis/condensation reaction of TEOS in presence of CTAB. The selectivity tests of the developed SiO₂-β-CD@MIP/GCE sensor indicated a high specificity towards ESOM compared with structurally related competitor molecules such as R-omeprazole (R-OM), R-lansoprazole, and S-lansoprazole. The developed sensor was successfully used to determine ESOM in tablets and commercial human serum samples with satisfactory recoveries (100.25 to 100.60%) and precision (RSD 0.46 to 0.66%).

Chiral Switch: Between Therapeutical Benefit and Marketing Strategy

Chirality of pharmaceutical substances is an important aspect in drug research because it determines how enantiomers will interact with chiral biological targets. Enantiomers of a chiral drug can have different pharmacokinetic and pharmacological profiles; consequently, using a single pure enantiomer instead of a racemate can enhance the effectiveness and/or safety of the treatment. The tendencies of modern pharmaceutical industry regarding the current market of chiral drugs are divided between the chiral switch of previously used racemates and the development of new enantiopure drugs. The term chiral switch refers to the replacement on the market of a previously approved racemate with its single enantiomer version. The potential advantages of chiral switch can be related to a higher therapeutic index due to better potency, selectivity and fewer adverse effects, faster onset of action and exposure of the patient to lower drug dosages. However, chiral switch is also a strategy that permits manufacturers to keep market exclusivity for chiral pharmaceuticals that have lost their patent protection, even if the pure enantiomers have not demonstrated higher effectiveness or safety profile compared with the racemates.

Effect of a state hospital formulary on medicines utilisation in Australia

ObjectiveThe provision of medicines through state public hospitals is comparatively restrictive compared with the federally funded Pharmaceutical Benefits Scheme (PBS). Individual states are progressively moving towards statewide medicines formularies. Although a statewide formulary has existed in Queensland for some time. The effects of hospital formularies on medicines utilisation and policy in Australia has not been quantified. Thus, the aim of the present study was to quantify the effects of the Queensland Health List of Approved Medicines (LAM) on medicines utilisation in Queensland at a state and PBS-purchasing level and describe the implications for medicines policy.MethodsThis study used a quasi-experimental design with an interrupted time series (with control for PBS) examining utilisation effects of medicines within the therapeutic classes of proton pump inhibitors and non-vitamin K oral anticoagulants with LAM listing or delisting.ResultsThe LAM was demonstrated to be highly effective at controlling utilisation within Queensland Health purchasing. Effects on PBS utilisation were evident, resulting in increases in generic utilisation (where available) and associated reduced total costs both within Queensland Health and to the PBS. The full benefit is likely underestimated due to limitations in the PBS datasets.ConclusionThe LAM is a highly effective state medicines policy tool with demonstrable effects on PBS utilisation. With increased use of statewide medicines formularies, this will be an increasingly relevant aspect of Australia's overall medicines policy.What is known about the topic?State medicines policy is comparatively restrictive compared with the federal PBS. Most Australian states have, or are developing, statewide medicines formularies.What does this paper add?By examining several classes of medicines, a substantial quantitative effect of the Queensland state formulary on both state and PBS medicines utilisation can be demonstrated. Increased use of generic medicines and reduced costs are seen.What are the implications for practitioners?With increased use of state medicines formularies, state medicines formularies will become increasingly relevant to medicines policy makers and advocates at both the state and federal level.

Evaluation of Trials Comparing Single-Enantiomer Drugs to Their Racemic Precursors: A Systematic Review

IMPORTANCE

Chiral switching, a strategy in which drug manufacturers develop a single-enantiomer formulation of a drug to be substituted for a racemic formulation, allows manufacturers to maintain market exclusivity for drugs losing patent protection, even without demonstrating superior efficacy or safety.

OBJECTIVE

To identify and characterize all randomized clinical trials (RCTs) directly comparing a Food and Drug Administration (FDA)-approved single-enantiomer drug against a previously approved racemic drug for 1 or more efficacy or safety end points.

EVIDENCE REVIEW

Drugs were identified using the Drugs@FDA database. Randomized clinical trials were identified using Ovid MEDLINE (1949 to October 22, 2019), Ovid Embase (1974 to October 22, 2019), Web of Science Core Collection (all years), ClinicalTrials.gov, and Cochrane Central Registry of Controlled Trials (CENTRAL, Wiley, Issue 8 of 12, October 22, 2019). Trials were characterized as favoring the single-enantiomer or racemic drugs based on whether the primary efficacy, secondary efficacy, and safety end points achieved each study's defined significance level (eg, P < .05). Trials were characterized as favoring neither drug if no statistically significant differences were reported for any end point or if both drugs were found to be superior for 1 or more separate end points.

FINDINGS

Fifteen FDA-approved single-enantiomer drugs were identified with racemic precursors approved in the US or Europe. For 3 single-enantiomer racemic drug pairs, no RCTs directly comparing the drugs were identified. For the remaining 12 pairs, 185 RCTs comparing efficacy or safety of the drug pairs were identified, 124 (67.0%) of which studied 1 pair (levobupivacaine/bupivacaine). There were 179 RCTs directly comparing drug pairs using efficacy end points, of which 23 (12.8%) favored the single enantiomer based on primary efficacy end point results. There were 124 RCTs directly comparing drug pairs using safety end points, of which 17 (13.7%) favored the single-enantiomer drug. For 9 of the 15 single-enantiomer drugs (60.0%), no RCTs were identified providing evidence of improved efficacy, based on primary end point results, or safety as compared with their racemic precursors.

CONCLUSIONS AND RELEVANCE

The results of this systematic review suggest that most newly marketed FDA-approved single-enantiomer drugs are infrequently directly compared with their racemic precursors, and when compared, they are uncommonly found to provide improved efficacy or safety, despite their greater costs.

Determination and Pharmacokinetics of Omeprazole Enantiomers in Human Plasma and Oral Fluid Utilizing Microextraction by Packed Sorbent and Liquid Chromatography-Tandem Mass Spectrometry

In the present work, the determination of omeprazole (OME) enantiomers in oral fluid and plasma samples was carried out utilizing microextraction by packed sorbent (MEPS) and liquid chromatography-tandem mass spectrometry. A chiral column with cellulose-SB phase was used for the first time for enantiomeric separation of OME with an isocratic elution system using 0.2% ammonium hydroxide in hexane-ethanol mixture (70 : 30, v/v) as the mobile phase. OME enantiomers were determined utilizing a triple quadrupole tandem mass spectrometer in positive ion mode (ESI+) monitoring mass transitions: m/z 346.3 ⟶ 198.0 for OME and m/z 369.98 ⟶ 252.0 for internal standard. The limits of detection and quantification of the present method for both enantiomers were 0.1 and 0.4 ng/mL, respectively. The method validation provided good accuracy and precision. The matrix effect factor was less than 5%, and no interfering peaks were observed. The interday precision values ranged from 2.2 to 7.5 (%RSD), and the accuracy of determinations varied from −9.9% to 8.3%. In addition, the pharmacokinetics (PK) of omeprazole enantiomers in healthy subjects after a single oral dose was investigated. (S)-Enantiomers showed higher levels than (R)-enantiomers throughout 24 h. It was found that the mean maximum concentrations of (R)- and (S)-omeprazole in plasma samples were about two times higher than in oral fluid.

Enantioselective in vitro ADME, absolute oral bioavailability, and pharmacokinetics of (-)-lumefantrine and (+)-lumefantrine in mice

Lumefantrine (LFN) is a chiral antimalarial drug. Enantioselective in vitro attributes and absolute oral pharmacokinetics for (-)-LFN and (+)-LFN have been characterized in mice. No stereoselectivity was seen with either of the enantiomers when compared with rac-LFN in the executed in vitro studies (solubility, metabolic stability, protein binding, permeability and blood partitioning). Post intravenous or oral administration of rac-LFN, the AUC_0-∞ and MRT of (+)-LFN was higher over (-)-LFN, which is reflected in higher clearance value for (-)-LFN. Following (-)-LFN intravenous administration to mice, the key PK parameters were comparable to (-)-LFN from rac-LFN; however, post intravenous administration of (+)-LFN alone to mice, the AUC_0-∞ was 1.3-fold higher than (+)-LFN from rac-LFN. Similarly, post oral administration of (-)-LFN to mice, both AUC_0-∞ and C_max were 1.3-fold higher than (-)-LFN from rac-LFN. On other hand, (+)-LFN showed 1.4-fold higher AUC_0-∞ and 1.7-fold higher C_max post oral administration over (+)-LFN from rac-LFN.

Me-too pharmaceutical products: History, definitions, examples, and relevance to drug shortages and essential medicines lists

We define a me‐too drug as a pharmacologically active compound that is structurally related to a first‐in‐class compound, regarded as belonging to the same therapeutic class as the original compound, and used for the same therapeutic purposes, but which may differ in some respects, such as specificity of pharmacological action, adverse reactions profile, or drug–drug interactions. We also offer definitions of related terms, including follow‐on drug and first‐in‐class. The therapeutic advantages of me‐too drugs may include improved target specificity, reduced risks of off‐target adverse reactions and drug–drug interactions, increased chance of benefit in some patients, and improved drug delivery and pharmacokinetics. Me‐too drugs can also demonstrate incremental innovation. Their availability may help in coping with drug shortages. However, they may occasionally cause unexpected adverse reactions that are not class effects. Tricyclic antidepressants, β‐blockers, and statins illustrate the diversity of me‐too drugs. Earlier compounds may be as effective as later ones, or more so. Tricyclic antidepressants have similar chemical structures, and compounds introduced after the first‐in‐class compound (imipramine) mostly offered little in the way of innovative features, but continue to be prescribed. In contrast, me‐too β‐blockers introduced after the first‐in‐class compound, pronethalol, have diverse structures and display several innovative features. Stereoisomers and biosimilars/biobetters provide special examples of me‐too drugs. Although many me‐too drugs offer no significant advantages over their predecessors, over 60% of the drugs listed on the World Health Organization's essential list are me‐toos. Different countries may choose different me‐too drugs when constructing essential medicines lists, partly explaining transnational differences between them.

Pharmacological Effects and Toxicogenetic Impacts of Omeprazole: Genomic Instability and Cancer

Omeprazole (OME) is commonly used to treat gastrointestinal disorders. However, long-term use of OME can increase the risk of gastric cancer. We aimed to characterize the pharmacological effects of OME and to correlate its adverse effects and toxicogenetic risks to the genomic instability mechanisms and cancer-based on database reports. Thus, a search (till Aug 2019) was made in the PubMed, Scopus, and ScienceDirect with relevant keywords. Based on the study objective, we included 80 clinical reports, forty-six in vitro, and 76 in vivo studies. While controversial, the findings suggest that long-term use of OME (5 to 40 mg/kg) can induce genomic instability. On the other hand, OME-mediated protective effects are well reported and related to proton pump blockade and anti-inflammatory activity through an increase in gastric flow, anti-inflammatory markers (COX-2 and interleukins) and antiapoptotic markers (caspases and BCL-2), glycoprotein expression, and neutrophil infiltration reduction. The reported adverse and toxic effects, especially in clinical studies, were atrophic gastritis, cobalamin deficiencies, homeostasis disorders, polyp development, hepatotoxicity, cytotoxicity, and genotoxicity. This study highlights that OME may induce genomic instability and increase the risk of certain types of cancer. Therefore, adequate precautions should be taken, especially in its long-term therapeutic strategies and self-medication practices.

Stereoselectivity evaluation of chiral chitosan microspheres delivery system containing rac-KET in vitro and in vivo

The influence of chiral excipient D-chitosan (CS) on the stereoselective release of racemic ketoprofen (rac-KET) microspheres has been investigated in comparison to those microspheres containing individual enantiomers in vitro and in vivo. Stereoselectivity was observed in vitro release test, with R-KET release slightly higher than that of S-KET, especially in 3% rac-KET loading microspheres. Stereoselectivity is dependent on the content of chiral excipient and pH of release medium. A molecular docking study between CS and KET enantiomers further revealed that S-KET has a stronger interaction with CS compared to R-KET. Moreover, the plasma concentration of KET enantiomers in rats shows substantial differences, as the plasma levels of S-KET were higher than those of R-KET. Plasma levels of enantiomers from the R-KET microspheres had similar stereoselectivity as rac-KET microspheres. The S/R ratio of rac-KET microspheres was significantly lower than that of rac-KET suspension (regular-release formulation) (p<.05), and the differences is 3–5 fold. Besides, rates of R-KET converted to S-KET exhibited differences between rac-KET microspheres and suspension. Similar results were also found between R-KET microspheres and suspension. All investigations suggest that the chitosan interacting preferentially with S-KET to R-KET significantly affect the stereoselective pharmacokinetics of rac-KET from chitosan microspheres in rats.

Effects of Plasma Albumin on the Pharmacokinetics of Esomeprazole in ICU Patients

Objectives

To evaluate the effects of plasma albumin on pharmacokinetics of esomeprazole in ICU patients.

Methods

This study was performed in 32 consecutive intensive care unit (ICU) patients. They were divided into two groups according to the plasma albumin levels. Nineteen patients with low plasma albumin levels (<30 g/L; male/female, 12/7) were assigned to low plasma albumin group (LPAG). Thirteen patients with plasma albumin levels >30 g/L (male/female, 9/4) were assigned to high plasma albumin group (HPAG). All patients were received intravenous (IV) of 40 mg esomeprazole in 5 min. Blood samples were collected via basilic vein at different time points and concentrations of esomeprazole were determined by UPLC-MS/MS.

Results

MRT_(0-∞), t_1/2, V, CL, and C_max between two groups were significantly difference (P<0.05). Compared with HPAG, MRT_(0-∞), t_1/2, and V of esomeprazole in LPAG were increased by 1.42-fold, 1.49-fold, and 1.24-fold, respectively; the maximum drug concentration of esomeprazole in LPAG was decreased to 82.5%. AUC_(0-∞) of LPAG was 1.23 times than that of group B. CL in LPAG was 80% of HPAG. There was no statistical difference between the two groups of AUC_(0-∞) and CL.

Conclusions

Some pharmacokinetic parameters of esomeprazole may be changed in ICU patients with low plasma albumin.

Industry Payments to Physicians and Prescriptions of Brand-Name Proton-Pump Inhibitors

OBJECTIVE

To characterize the association between industry payments and prescriptions of 2 brand-name proton-pump inhibitors (PPIs).

STUDY DESIGN

Cross-sectional retrospective.

SETTING

Physicians nationwide.

SUBJECTS AND METHODS

We identified all physicians receiving industry payments for Dexilant and Nexium 2014-2015 from the Open Payments database. We linked this to records of prescriptions for PPIs paid for by Medicare Part D these same years and compared the proportion of prescriptions written for Dexilant and Nexium in industry-compensated vs nonindustry compensated physicians. The number and dollar amount of payments were associated with the rate of drug prescriptions.

RESULTS

We identified 254,452 physicians prescribing PPIs; 8586 and 2766 physicians received industry payments for Dexilant and Nexium, respectively. A total of 5052 of 7876 (64%) physicians compensated for Dexilant prescribed Dexilant vs 39,778 of 246,571 (16%) noncompensated physicians ( P < .001). For Nexium, 2525 of 2654 (95%) compensated physicians prescribed Nexium, compared to 123,913 of 252,067 (49%) noncompensated physicians. For both Dexilant and Nexium, there was a significant correlation between the number (ρ = 0.22, P < .001 and ρ = 0.12, P < .001) and dollar amount (ρ = 0.22, P < .001 and ρ = 0.13, P < .001) of payments and the percentage of prescriptions written for the compensated drug. Industry payments for Nexium remained associated with rate of prescription even after generic esomeprazole became available.

CONCLUSION

Both the number and dollar amount of industry payments were associated with increased prescriptions for both Dexilant and Nexium. Although unable to show causality, this study suggests that industry payments may increase physician prescriptions of costly, brand-name drugs.