Dilevalol: a selective beta-2 adrenergic agonist vasodilator with beta adrenergic blocking activity

Protective effects of total flavonoids from Qu Zhi Qiao (fruit of Citrus paradisi cv. Changshanhuyou) on OVA-induced allergic airway inflammation and remodeling through MAPKs and Smad2/3 signaling pathway

Allergic asthma is one of the inflammatory diseases, which has become a major public health problem. Qu zhi qiao (QZQ), a dry and immature fruit of Citrus paradisi cv. Changshanhuyou, has various flavonoids with pharmacological properties. However, there is a knowledge gap on the pharmacological properties of QZQ on allergic asthma. Therefore, here, we explored the efficacy and mechanism of total flavonoids from QZQ (TFCH) on allergic asthma. We extracted and purified TFCH and conducted animal experiments using an Ovalbumin (OVA)-induced mice model. Bronchoalveolar lavage fluid and Swiss-Giemsa staining were used to count different inflammatory cells in allergic asthma mice. We conducted histopathology and immunohistochemistry to evaluate the changes in the lungs of allergic asthma mice. Moreover, we used ELISA assays to analyze chemokines and inflammatory cytokines. Furthermore, western blot analyses were conducted to elucidate the mechanism of TFCH on allergic asthma. We established that TFCH has anti-inflammatory effects and inhibits airway remodeling, providing a potential therapeutic strategy for allergic asthma.

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

Background

Both omeprazole and its S enantiomer (esomeprazole) have been available and used to treat  symptoms of gastroesophageal reflux disease (GERD) and conditions associated with excessive stomach acid secretion for more than a decade. Controversy exists over improved efficacy of S enantiomer (esomeprazole) over parent racemate (omeprazole). However, a comparison of the clinical outcomes of these products may reveal the rationale for switching from the racemate to single enantiomer. Since enantiomers of omeprazole are equipotent, we compared the outcomes of equal doses of each product to see if both actually differ in their efficacy’s or the reported superiority of S enantiomer is just a dose effect.

Methods

A web search was carried out for randomized controlled trials with head-to-head comparisons of omeprazole and S-omeprazole. The data were abstracted and after calculating theodd ratios (OR) for the outcomes reported in each study, the combined overall odd ratios (OR’) were estimated. The random effect inverse variance method with omeprazole as the reference (OR” = 1) was used.

Results

Out of 1171 studies, 14 were deemed eligible. There was no significant difference in the therapeutic success between omeprazole and S-omeprazole as a part of triple therapy for the treatment of H. pylori in both intention-to-treat (OR’, 1.06; CI, 0.83, 1.36; p = 0.63) as well as per-protocol analysis (OR’, 1.07; CI, 0.84, 1.36; p = 0.57). For the treatment of gastro-oesophageal reflux disease, S-omeprazole was significantly but marginally superior to the racemate (OR’, 1.18; CI, 1.01, 1.38; p = 0.04). The two products were equipotent in all metrics used to assess intragastric pH except for the % patients maintaining a 24 h gastric pH above 4 (1.57; CI, 1.04, 2.381; p = 0.03).

Conclusion

The therapeutic benefit of chiral switch of omeprazole is questionable considering the substantially greater economic burden involved.

Three-dimensional pharmacology, a subject ranging from ignorance to overstatements

Stereoselectivity has been known to play a role in drug action for 100 years or more. Nevertheless, chiral drugs have been developed and used as racemates, neglecting the fact that they comprise mixtures of two or more compounds which may have quite different pharmacological properties. A very limited access to pure enantiomers in the past has been responsible for this unsatisfactory state of affairs. During the last 20 years, significant achievements have made it possible to perform stereoselective synthesis and analysis. Today, novel chiral drugs are as a rule developed as single enantiomers. Yet, studies of old racaemic drugs are still designed, performed and published without mention of the fact that two or more compounds are involved. In recent years, a number of old racaemic drugs have been re-evaluated and re-introduced into the clinical area as the pure, active enantiomer (the eutomer). While in principle correct, the clinical benefit of this shift from a well established racaemate to a pure enantiomer often seems to be limited and sometimes exaggerated. Racaemic drugs with a deleterious enantiomer that does not contribute to the therapeutic effect (the distomer), may have been sorted out in the safety evaluation process. However, in the future any pharmacological study of racaemic drugs must include the pure enantiomers. This will generate new, valuable information on stereoselectivity in drug action and interaction.

Chiral switches

Developments in synthetic and analytical chemistry have provided the tools to differentiate between two enantiomers (mirror images) of drugs or between the parent compound and metabolite(s) with respect to desired and undesired pharmacological effects. Several drugs are now marketed or being developed as single enantiomers in place of a previous racemic mixture, a process known as "chiral switching". It is easier to understand "pure" as opposed to "mixture" pharmacology but whether the promise of chiral (and metabolite) switches will translate into real clinical advances remains to be seen.

Stereochemical aspects of pharmacotherapy

Over the past 15 years stereoselectivity has become a well-recognized consideration in clinical pharmacology. Drugs that have an asymmetric center or plane of symmetry within their molecular structure are said to be chiral. They are available as pairs of nonsuperimposable mirror images, called enantiomers, that share essentially the same physicochemical properties. These three-dimensional structural differences, however, can translate into enantiospecific pharmacologic or pharmacokinetic properties, which may be important in understanding the clinical pharmacology of chiral drugs. Most chiral drugs are available as the racemate, in which equal proportions of the two enantiomers are administered concurrently. The pharmacologic and disposition properties of many chiral drugs are documented to be stereospecific, and this has influenced the regulatory requirements for the approval of new drug candidates. Due to this influence on new drug development, the possible issues surrounding racemic drugs will undoubtedly affect the types of pharmaceuticals that are used clinically in the next century. Accordingly, considerable advances have been made in producing optically pure drug. It should be emphasized, however, that stereochemically pure drugs are not necessarily superior to the respective racemates.