Fabrication and Evaluation of Spironolactone-Loaded Nanostructured Lipid Carries for Cardiac Tissue Regeneration

Background:

Spironolactone (SP) is a lipophilic aldosterone receptor antagonist that few studies have reported its effect on cardiac remodeling. In addition, fewer researches have considered its influence on cardiomyocyte viability and potential benefits for myocardial tissue remodeling.

Method:

In this study, stearic acid (SA) (solid lipid) and oleic acid (OA) (liquid lipid) were utilized to produce nanostructured lipid carries (NLCs) (various ratios of SA to OA and water amount, F1: 80:20 [30 ml water], F2: 80:20 [60 ml water], F3: 70:30 [30 ml water], and F4: 70:30 [60 ml water]) containing SP and their particle size, polydispersity index, zeta potential, entrapment efficiency, and release profile were measured. The purpose of encapsulating SP in NLCs was to provide a sustain release system. Meanwhile, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay with different concentrations of SP-loaded NLCs (SP-NLCs) was conducted to evaluate the cytotoxicity of the NLCs on rat myocardium cells (H9C2).

Results:

Increase of oil content to 10 wt% reduced the particle size from 486 nm (F1) to 205 nm (F2). Zeta potential of the samples at around −10 mV indicated their agglomeration tendency. After 48 h, SP-NLCs with the concentrations of 5 and 25 μM showed significant improvement in cell viability while the same amount of free SP-induced cytotoxic effect on the cells. SP-NLCs with higher concentration (50 μM) depicted cytotoxic effect on H9C2 cells.

Conclusion:

It can be concluded that 25 μM SP-NLCs with sustain release profile had a beneficial effect on cardiomyocytes and can be used as a mean to improve cardiac tissue regeneration.

A highly selective probe for UDP-glucuronosyltransferase 2B7 (UGT2B7) in human microsomes: isoform specificity, kinetic characterization, and applications

3-Epideacetycinobufagin (EDCB) was found to be a highly isoform-specific probe for 3-glucuronidation mediated by UDP-glucuronosyltransferase 2B7 (UGT2B7). The reaction was well-characterized, suggesting that EDCB can be used to measure the catalytic activity of UGT2B7.

The mineralocorticoid receptor antagonist spironolactone enhances morphine antinociception

BACKGROUND

Spironolactone, a commonly used mineralocorticoid receptor antagonist, has been reported to potentiate the effect of morphine in the rat. The aim of this study was to investigate the effects of spironolactone on morphine antinociception and tissue distribution.

METHODS

The effects of spironolactone on acute morphine-induced antinociception, induction of morphine tolerance and established morphine tolerance were studied with tail-flick and hot plate tests in male Sprague-Dawley rats. Serum, brain, and liver morphine and its metabolite concentrations were quantified using high-pressure liquid chromatography-tandem mass spectrometry. Spironolactone was also administered with the peripherally acting, P-glycoprotein (P-gp) substrate loperamide to test whether spironolactone allows loperamide to pass the blood-brain barrier.

RESULTS

Spironolactone (50 mg/kg, i.p.) had no antinociceptive effects of its own, but it enhanced the antinociceptive effect of morphine in both thermal tests. Two doses of spironolactone enhanced the maximum possible effect (MPE) from 19.5% to 100% in the hot plate test 90 min after administration of 4 mg/kg morphine. Morphine concentrations in the brain were increased fourfold at 90 min by spironolactone. Spironolactone did not inhibit the formation of morphine-3-glucuronide. Acute spironolactone restored morphine antinociception in morphine-tolerant rats but did not inhibit the development of tolerance. The peripherally restricted opioid, loperamide (10 mg/kg), had no antinociceptive effects when administered alone, but co-administration with spironolactone produced a 40% MPE in the hot plate test.

CONCLUSIONS

Spironolactone has no antinociceptive effects in thermal models of pain, but it enhances the antinociceptive effects of morphine mainly by increasing morphine central nervous system concentrations, probably by inhibiting P-gp.

Albumin stimulates the activity of the human UDP-glucuronosyltransferases 1A7, 1A8, 1A10, 2A1 and 2B15, but the effects are enzyme and substrate dependent

Human UDP-glucuronosyltransferases (UGTs) are important enzymes in metabolic elimination of endo- and xenobiotics. It was recently shown that addition of fatty acid free bovine serum albumin (BSA) significantly enhances in vitro activities of UGTs, a limiting factor in in vitro–in vivo extrapolation. Nevertheless, since only few human UGT enzymes were tested for this phenomenon, we have now performed detailed enzyme kinetic analysis on the BSA effects in six previously untested UGTs, using 2–4 suitable substrates for each enzyme. We also examined some of the previously tested UGTs, but using additional substrates and a lower BSA concentration, only 0.1%. The latter concentration allows the use of important but more lipophilic substrates, such as estradiol and 17-epiestradiol. In five newly tested UGTs, 1A7, 1A8, 1A10, 2A1, and 2B15, the addition of BSA enhanced, to a different degree, the in vitro activity by either decreasing reaction’s K_m, increasing its V_max, or both. In contrast, the activities of UGT2B17, another previously untested enzyme, were almost unaffected. The results of the assays with the previously tested UGTs, 1A1, 1A6, 2B4, and 2B7, were similar to the published BSA only as far as the BSA effects on the reactions’ K_m are concerned. In the cases of V_max values, however, our results differ significantly from the previously published ones, at least with some of the substrates. Hence, the magnitude of the BSA effects appears to be substrate dependent, especially with respect to V_max increases. Additionally, the BSA effects may be UGT subfamily dependent since K_m decreases were observed in members of subfamilies 1A, 2A and 2B, whereas large V_max increases were only found in several UGT1A members. The results shed new light on the complexity of the BSA effects on the activity and enzyme kinetics of the human UGTs.