Enhanced Aqueous Solubility of Phenolic Antioxidants Using Modified β-Cyclodextrins

Evaluation of the antiulcerogenic activity of violacein and its modulation by the inclusion complexation with beta-cyclodextrin

The effects of beta-cyclodextrin (betaCD) inclusion complexation on the ability of violacein to prevent gastric ulceration in mice were studied. Violacein-betaCD inclusion complexes were prepared in 1:1 and 1:2 molar ratios and analysed by differential scanning calorimetry and powder X-ray diffractometry. Violacein previously administered orally at 10 mg/kg significantly reduced indomethacin-induced gastric lesions, as well as 100 mg/kg of cimetidine (positive control). However, betaCD complexation in both molar ratios significantly potentiated the protective action of violacein. In the HCl--ethanol-induced gastric ulcer model, violacein and the 1:2 inclusion complex (10 mg/kg, p.o.) inhibited gastric damage by almost 85%, whereas a 63% reduction was observed for the positive control, lansoprazole, at 30 mg/kg. In contrast, treatment with the 1:1 inclusion complex resulted in almost total disappearance of the antiulcer activity in this model. No significant changes in stress-induced gastric injury were found. In addition, the 1:2 inclusion complex improved the antilipoperoxidant activity of violacein in rat liver cells exposed to t-butyl hydroperoxide, whereas the 1:1 complex was less active than violacein. In summary, the 1:2 betaCD inclusion complex has gastroprotective properties similar to or higher than that of violacein. An increase in mucosal defensive mechanisms and protection against peroxidative damage might be involved.

Pharmacokinetic-toxicodynamic relationships of adriamycin in rat: prediction of butylated hydroxyanisole-mediated reduction in anthracycline cardiotoxicity

Adriamycin, an anthracycline antibiotic, has broad antitumour activity with cumulative dose-dependent cardiotoxicity as its major side effect. This study was designed to quantify and correlate the cardiotoxicity and pharmacokinetics of adriamycin in-vivo in rat. The influence of antioxidant (butylated hydroxyanisole, BHA) co-therapy on the cardiotoxicity and disposition of adriamycin was also studied. Cardiotoxicity was estimated by serially measuring serum creatine kinase (CK) levels after intravenous administration of adriamycin (4, 10, 20, and 30 mg kg-1) and adriamycin-BHA (10 and 30 mg kg-1 each). Peak serum CK concentrations (CKmax) and area under serum CK-time curves (AUCCK) were used as cardiotoxicity indices. Pharmacokinetic studies were undertaken by sampling plasma and urine from distinct groups of rats treated with [14C]adriamycin (at the above doses) and [14C]adriamycin-BHA (10 mg kg-1 each). Co-administration of BHA resulted in a significant reduction in CKmax and also resulted in a significant reduction in the renal clearance of adriamycin which was fully compensated by an increase in its metabolic clearance. A linear increase in the area under the plasma adriamycin concentration-time curves (AUC) with increasing adriamycin doses suggested dose-independent disposition of the drug. The most significant pharmacokinetic-toxicodynamic relationships included: CKmax = 2.25 x 10(2) exp (4 x 10(-4) AUC), r2 = 0.941, P < 0.05 and AUCCK = 1.3 x 10(4) exp(2 x 10(-4) AUC0-tmax), r2 = 0.918, P < 0.05 where, AUC0-tmax is the area under the adriamycin concentration-time curve from time 0 to the time of the peak CK level. The results strongly indicate that the drug-induced cardiotoxicity is initiated shortly after dosing when drug concentrations are high and accumulates with continued exposure. The predicted cardiotoxic indices, obtained from altered adriamycin pharmacokinetic parameters as a result of BHA co-therapy, compared favourably with the observed values.

Protective effect of butylated hydroxyanisole on adriamycin-induced cardiotoxicity

Adriamycin has a wide spectrum of antitumour activity with dose-related cardiotoxicity as a major side effect. This cardiotoxicity has been suggested to result from the generation of oxygen free radicals. The objective of the present study was to investigate the influence of the antioxidant, butylated hydroxyanisole co-therapy on the cardiotoxicity of adriamycin, in-vivo. The aqueous solubility of butylated hydroxyanisole was enhanced by inclusion complex formation with hydroxypropyl-beta-cyclodextrin. The extent of drug-induced myocardial damage in rats was assessed using intravenous 111In-labelled antimyosin Fab and chronological changes in serum creatine kinase levels. There was a dose-related increase in myocardial antimyosin uptake in rats, which reached a plateau at an adriamycin dose of 10 mg kg-1. The antimyosin uptake at this dose (% dose g-1 = 0.1942 +/- 0.0150, n = 8) was significantly reduced by co-administration of butylated hydroxyanisole with adriamycin (10 mg kg-1 of each) to 0.1462 +/- 0.0116 (n = 5, P < 0.05). Assessment of cardiotoxicity in the rats was also performed by measuring serial changes in serum creatine kinase levels. Increasing doses of adriamycin caused an increase in serum creatine kinase levels with peak values obtained between 2 and 8 h after dosing. These values decreased upon co-administration of butylated hydroxyanisole with adriamycin at 10 mg kg-1, each and 30 mg kg-1 each by 29 and 41%, respectively. On the other hand, butylated hydroxyanisole did not inhibit the tumouricidal activity of adriamycin as investigated in-vitro using the NMU rat mammary adenocarcinoma cell-line. The significant reduction in anthracycline cardiotoxicity by butylated hydroxyanisole coadministration may result from its scavenging action on adriamycin-mediated free-radical formation or its enhancement of activity of enzymes involved in the metabolism of adriamycin.