Development of a chromatographic method for the determination of saquinavir in plasma samples of HIV patients

Nasal Gel Loaded with Amphotericin Nanotransferosomes as Antifungal Treatment for Fungal Sinusitis

On the basis of fungal involvement, rhinosinusitis is categorized into allergic, mycetoma, chronic, and acute invasive types. The aim of the current study was to evaluate the efficacy of an amphotericin gel in situ loaded with nanotransferosomes against Aspergillus flavus, which causes allergic rhinosinusitis. A Box–Behnken design was utilized to study the interaction among the nanotransferosomes and optimize independent variables in formulating them, in order to match the prerequisites of selected responses. The optimal formulation was determined to be 300 mg/mL soybean lecithin, 200 mg/mL amphotericin B (AMP), and 150 mg/mL clove oil, resulting in a particle size of 155.09 nm, 84.30% entrapment efficacy (EE), inhibition zone of 16.0 mm, and 0.1197 mmol serum creatinine. The optimized batch was further prepared into an in situ gel and evaluated for various parameters. The optimized formulation released 79.25% AMP and enhanced permeation through the nasal membrane, while the other formulations did not achieve complete absorption. According to in vivo tests using rabbits as animal models, the optimized AMP-nanotransferosomal formulations (NT) in in situ gel result in a non-significant difference among the various kidney function parameters. In conclusion, nasal in situ gel loaded with AMP-clove oil nanotreansfersomes can act as a promising novel carrier that enhances antifungal activity and decreases AMP nephrotoxicity.

Effect of P-glycoprotein on the rat intestinal permeability and metabolism of the BDDCS class 1 drug verapamil

The Biopharmaceutics Drug Disposition Classification System (BDDCS) predicts intestinal transporter effects to be clinically insignificant following oral dosing for highly soluble and highly permeable/metabolized drugs (class 1 drugs). We investigated the effect of inhibiting P-glycoprotein (P-gp) on the in vitro rat intestinal permeability (Papp) and metabolism of the class 1 drug verapamil. Jejunal segments from Sprague-Dawley rats fasted overnight were mounted in Ussing chambers filled with 10 mL of Krebs-Ringer buffer (KRB). For P-gp inhibition studies, GG918 0.5 μM was added to the KRB solution. The experiment started by the addition of verapamil (1 or 10 μM) to either apical or basolateral sides. Samples from verapamil donor and receiver compartments were collected at 30 s and 0.166, 0.5, 1, 1.83 and 3 h after the start of the experiment. Analysis of verapamil and its major metabolite, norverapamil, in the samples and intracellularly at 3 h was performed by HPLC. The same experiment was repeated with norverapamil 10 μM (verapamil metabolite), digoxin 100 nM (positive control for P-gp activity) and atorvastatin 1 and 10 μM (example of a class 2 drug). For 1 μM verapamil, efflux ratio (B to A Papp/A to B Papp) was 4.6 and markedly decreased by GG918 (efflux ratio = 1.1). For 10 μM verapamil efflux ratio was 4.1 (control) vs 1.8 (GG918), comparable to the change seen for digoxin 100 nM with an efflux ratio of 3.6 (control) vs 1.6 (with GG918) and atorvastatin (efflux ratio of 5.2 and 3.0 for atorvastatin 1.0 and 10 μM, respectively, changed to 1.0 and 0.65 with GG918). The changes observed in the norverapamil 10 μM experiment were also significant, where efflux ratio decreased from 13.5 (control) to 1.5 (GG918). The extraction ratio (ER) of 10 μM verapamil to norverapamil decreased from 0.41 after an apical dose to 0.21 after a basolateral dose, but was unaffected by the incubation with GG918. The results suggest that P-gp inhibition has an effect on class 1 drug verapamil and class 2 drug atorvastatin Papp in the rat intestine. Moreover, a stronger P-gp effect on the Papp of the more polar norverapamil metabolite was observed. Papp changes caused by the P-gp inhibitor GG918 do not affect the extent of verapamil metabolism.

Modulatory role of verapamil treatment on the cardiac electrophysiological effects of cisapride

The role of transport proteins in the distribution of drugs in various tissues has obvious implications for drug effects. Recent reports indicate that such transporters are present not only in the liver, intestine, or blood−brain barrier but also in the heart. The objective of our study was to determine whether treatment of animals with verapamil, a well-known L-type calcium channel blocker with modulatory properties of membrane transporters, would alter distribution and cardiac electrophysiological effects of an IKrblocker. Male guinea pigs (n = 72) were treated with either saline or verapamil at various doses (1.5 to 15 mg/kg) and for various durations (1 to 7 d). Animals were sacrified 24 h after the last dose of verapamil (or saline), and their hearts were isolated and retroperfused with cisapride, a gastrokinetic drug with IKrblockade properties. In hearts obtained from animals treated with vehicle, 50 nmol/L cisapride prolonged MAPD90by 15 ± 5 ms vs. 36 ± 8 ms in hearts from animals treated with verapamil 15 mg·kg−1·d−1for 5 d (p < 0.01). Treatment effects were dose- and time-dependent. Cardiac myocytes isolated from animals treated with vehicle or verapamil were incubated for 3 h with 100 ng/mL cisapride. Intracellular concentrations of cisapride in cardiac myocytes from animals treated with verapamil were 1.6-fold higher than those measured in myocytes from animals treated with vehicle (p < 0.01). The increase in intracellular concentrations of cisapride and potentiation of cisapride electrophysiological effects suggest that chronic treatment with drugs such as verapamil may modulate drug effects on the QT interval because of an increased access to intracellular binding sites on IKrchannels.

Determination of saquinavir and ritonavir in human plasma by reversed-phase high-performance liquid chromatography and the analytical error function

Two simple and reproducible high-performance liquid chromatography methods with ultraviolet detection were developed and validated for the quantitation of two protease inhibitors, saquinavir and ritonavir, in human plasma. The same single liquid-liquid extraction procedure with ethyl acetate-hexane (50:50, v/v), reversed-phase column and mobile phase were used. The analyses were accomplished using a Luna C(18) column (150 mm x 4.6mm i.d.) with a C(18) guard column and, the mobile phase consisted of acetonitrile and 70 mM KH(2)PO(4) adjusted to pH 5 with 80 mM Na(2)HPO(4) (46:54, v/v). The wavelength was set at 240 nm for saquinavir and at 210 nm for ritonavir. The retention times were 6.4 min for saquinavir and 8.3 min for ritonavir. The methods were linear over the range of 100-2500 ng/ml for saquinavir and 200-2500 ng/ml for ritonavir. Intra and inter-day precision and accuracy were less than 10.2% for both drugs. Recovery were 90 and 87% for saquinavir and ritonavir, respectively. The drugs were stable at different relevant storage and working conditions. After the validation, their analytical error functions were established as standard deviation (S.D., ng/ml) = 4.84 + 7.14 x 10(-2)C (C is the theoretical concentration value) for saquinavir and S.D. (ng/ml) = 39.98 + 2.40 x 10(-5)C(2) for ritonavir.