Disposition of [14C]Ruboxistaurin in Humans

A protein kinase C α and β inhibitor blunts hyperphagia to halt renal function decline and reduces adiposity in a rat model of obesity-driven type 2 diabetes

Type 2 diabetes (T2D) and its complications can have debilitating, sometimes fatal consequences for afflicted individuals. The disease can be difficult to control, and therapeutic strategies to prevent T2D-induced tissue and organ damage are needed. Here we describe the results of administering a potent and selective inhibitor of Protein Kinase C (PKC) family members PKCα and PKCβ, Cmpd 1, in the ZSF1 obese rat model of hyperphagia-induced, obesity-driven T2D. Although our initial intent was to evaluate the effect of PKCα/β inhibition on renal damage in this model setting, Cmpd 1 unexpectedly caused a marked reduction in the hyperphagic response of ZSF1 obese animals. This halted renal function decline but did so indirectly and indistinguishably from a pair feeding comparator group. However, above and beyond this food intake effect, Cmpd 1 lowered overall animal body weights, reduced liver vacuolation, and reduced inguinal adipose tissue (iWAT) mass, inflammation, and adipocyte size. Taken together, Cmpd 1 had strong effects on multiple disease parameters in this obesity-driven rodent model of T2D. Further evaluation for potential translation of PKCα/β inhibition to T2D and obesity in humans is warranted.

Determination of Ruboxistaurin analysis in rat plasma utilizing LC–MS/MS technique

Background

Ruboxistaurin (RBX) used to treat retinopathy in diabetic patients which caused by microvascular damage and leakage which contributes to visual loss. There are no published studies on the use of liquid chromatography-tandem mass spectrometry for development and validation of a simple, sensitive, and accurate method for measuring RBX in rat plasma.

Method

Chromatographic separation of RBX was achieved using ultra-performance liquid chromatography. Multiple-reaction monitoring quantification used RBX [M + H] + ion at m/z 469.18 and daughter ions at m/z 84, 58.12, and 98.10. Atorvastatin was used as internal standard (IS), has a single daughter ion, and was identified using m/z 559.6 → 249.9. Validation of the liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for RBX in rat plasma for linearity (greater than0.997) was carried out at 25-1000 ng/mL.

Results

In rat plasma, the accuracy was within 3.4%, and the intra- and inter-day precision was within 11.8%. Stability, recovery, and matrix effect were all within acceptable limits. The drug retention time (0.85 ± 0.03 min) was remarkably short.

Conclusion

The method developed in the current study is suitable to quantify RBX in plasma or bulk doses.

Ruboxistaurin for the treatment of diabetic peripheral neuropathy: a systematic review of randomized clinical trials

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus. Protein kinase C (PKC) inhibitor's has been thought to be a potential disease modifying drug's in DPN as it slows or reverse neuropathy's progression. To assesses the efficacy and safety of ruboxistaurin on the progression of symptoms, signs, or functional disability in DPN.

METHODS

A systematic review of the literature databases like PubMed, ProQuest, EBSCO, EMBASE, and Cochrane Central was performed up to August 2012. We included randomized controlled trials (RCTs) comparing PKC inhibitor ruboxistaurin (RBX) with control and lasting at least 6 months. Our primary outcome measure was change in neurological examination, measured by neurological total symptom score (NTSS) and vibration detection threshold (VDT). Secondary outcome measures were total quality of life (QoL), skin microvascular blood flow and others.

RESULTS

Six RCTs were included in review. Change in neurological function assessed by NTSS was reported in six studies, out of which significant difference between the RBX and placebo group seen in four studies favouring treatment group while remaining two studies reported no significant difference. VDT was assessed in only one study in which no significant difference seen between RBX and placebo group. Two studies reported significant improvement in QoL data. Safety data was reported in only two studies in which none of side effect was related to RBX.

CONCLUSION

RBX had effects on DPN in some studies, but the evidence is not enough for meta-analysis and firm conclusion.

Assessment of reactive metabolites in drug-induced liver injury

The aim of the current review is to summarize present methods used for the determination of reactive metabolites, which can predict drug-induced liver injury (DILI) in drug discovery and development. DILI is one of the most frequent reasons for the withdrawal of an approved drug from the market, and it accounts for up to 50% of acute liver failure cases. This review is structured into three sections. The first section is a general overview of the relationship between drug metabolism and liver injury. The second section introduces in vitro methods for the assessment of reactive metabolites for drug discovery and development. In the third section, limitations and future directions for the development of methods for predicting DILI are described.

Metabolites in safety testing (MIST): considerations of mechanisms of toxicity with dose, abundance, and duration of treatment

In previous papers, we have offered a strategic framework regarding metabolites of drugs in humans and the need to assess these in laboratory animal species (also termed Metabolites in Safety Testing or MIST; Smith and Obach, Chem. Res. Toxicol. (2006) 19, 1570-1579). Three main tenets of this framework were founded in (i) comparisons of absolute exposures (as circulating concentrations or total body burden), (ii) the nature of the toxicity mechanism (i.e., reversible interaction at specific targets versus covalent binding to multiple macromolecules), and (iii) the biological matrix in which the metabolite was observed (circulatory vs excretory). In the present review, this framework is expanded to include a fourth tenet: considerations for the duration of exposure. Basic concepts of pharmacology are utilized to rationalize the relationship between exposure (to parent drug or metabolite) and various effects ranging from desired therapeutic effects through to severe toxicities. Practical considerations of human ADME (absorption-distribution-metabolism-excretion) data, to determine which metabolites should be further evaluated for safety, are discussed. An analysis of recently published human ADME studies shows that the number of drug metabolites considered to be important for MIST can be excessively high if a simple percentage-of-parent-drug criterion is used without consideration of the aforementioned four tenets. Concern over unique human metabolites has diminished over the years as experience has shown that metabolites of drugs in humans will almost always be observed in laboratory animals, although the proportions may vary. Even if a metabolite represents a high proportion of the dose in humans and a low proportion in animals, absolute abundances in animals frequently exceed that in humans because the doses used in animal toxicology studies are much greater than therapeutic doses in humans. The review also updates the enzymatic basis for the differences between species and how these relate to MIST considerations.