Formulation and in vitro evaluation of self-nanoemulsifying liquisolid tablets of furosemide.

Self-nanoemulsifying drug delivery systems (SNEDDS) were used to enhance the dissolution rate of furosemide as a model for class IV drugs and the system was solidified into liquisolid tablets. SNEDDS of furosemide contained 10% Castor oil, 60% Cremophor EL, and 30% PEG 400. The mean droplets size was 17.9 ± 4.5 nm. The theoretical model was used to calculate the amounts of the carrier (Avicel PH101) and coating materials (Aerosil 200) to prepare liquisolid powder. Carrier/coating materials ratio of 5/1 was used and Ludipress was added to the solid system, thus tablets with hardness of 45 ± 2 N were obtained. Liquisolid tablets showed 2-folds increase in drug release as compared to the generic tablets after 60 min in HCl 0.1 N using USP apparatus-II. Furosemide loaded SNEDDS tablets have great prospects for further in vivo studies, and the theoretical model is useful for calculating the adequate amounts of adsorbents required to solidify these systems.

Assessing Transporter-Mediated Natural Product-Drug Interactions Via In vitro-In Vivo Extrapolation: Clinical Evaluation With a Probe Cocktail.

The botanical natural product goldenseal can precipitate clinical drug interactions by inhibiting cytochrome P450 (CYP) 3A and CYP2D6. Besides P-glycoprotein, effects of goldenseal on other clinically relevant transporters remain unknown. Established transporter-expressing cell systems were used to determine the inhibitory effects of a goldenseal extract, standardized to the major alkaloid berberine, on transporter activity. Using recommended basic models, the extract was predicted to inhibit the efflux transporter BCRP and uptake transporters OATP1B1/3. Using a cocktail approach, effects of the goldenseal product on BCRP, OATP1B1/3, OATs, OCTs, MATEs, and CYP3A were next evaluated in 16 healthy volunteers. As expected, goldenseal increased the area under the plasma concentration-time curve (AUC0-inf ) of midazolam (CYP3A; positive control), with a geometric mean ratio (GMR) (90% confidence interval (CI)) of 1.43 (1.35-1.53). However, goldenseal had no effects on the pharmacokinetics of rosuvastatin (BCRP and OATP1B1/3) and furosemide (OAT1/3); decreased metformin (OCT1/2, MATE1/2-K) AUC0-inf (GMR, 0.77 (0.71-0.83)); and had no effect on metformin half-life and renal clearance. Results indicated that goldenseal altered intestinal permeability, transport, and/or other processes involved in metformin absorption, which may have unfavorable effects on glucose control. Inconsistencies between model predictions and pharmacokinetic outcomes prompt further refinement of current basic models to include differential transporter expression in relevant organs and intestinal degradation/metabolism of the precipitant(s). Such refinement should improve in vitro-in vivo prediction accuracy, contributing to a standard approach for studying transporter-mediated natural product-drug interactions.

Impact of short-acting loop diuretic doses and cardiac sympathetic nerve abnormalities on outcomes of patients with reduced left ventricular function.

Recent studies reported that high doses of short-acting loop diuretics are associated with poor outcomes in patients with heart failure (HF). Short-acting loop diuretics have been shown to activate the renin-angiotensin system (RAS) and have no favorable effects on cardiac sympathetic nervous system (SNS) activity. The goal of this study is to investigate the relationship between daily doses of furosemide and the outcomes of patients with left ventricular dysfunction (LVD) from the viewpoint of cardiac SNS abnormalities using iodine-123-labeled metaiodobenzylguanidine (l-MIBG) myocardial scintigraphy.We enrolled 137 hospitalized patients (62.5 ±â€Š14.2 years old, 103 men) with LVEF < 45% who underwent l-MIBG myocardial scintigraphy. A delayed heart-to-mediastinum ratio (delayed HMR) was assessed using l-MIBG scintigraphy. Cardiac events were defined as cardiac death or re-hospitalization due to the deterioration of HF. Cox proportional hazard analysis was used to identify predictors of cardiac events.Cardiac events occurred in 57 patients in a follow-up period of 33.1 ±â€Š30 months. In a multivariate Cox proportional hazard analysis, delayed HMR and furosemide doses were identified as independent predictors of cardiac events (P = .0042, P = .033, respectively). Inverse probability of treatment weighting Cox modeling showed that the use of furosemide (≥40 mg /day) was associated with cardiac events with a hazard ratio of 1.96 (P = .003). In the Kaplan-Mayer analysis, the cardiac event-free survival rate was significantly lower in patients treated with high doses of furosemide (≥60 mg/day vs 40-60 mg/day vs <40 mg/day, the Log-rank test P < .0001). In a receiver-operating characteristic (ROC) analysis, the cut-off value for cardiac events was 40 mg/day of furosemide. The cardiac event-free rate was significantly lower in patients with delayed HMR <1.8 (median value) and receiving furosemide ≥40 mg/day than in other patients (the Log-rank test P < .0001). Significant differences in cardiac event rates according to furosemide doses among patients with delayed HMR <1.8 were observed among patients without ß-blocker therapy (P = .001), but not among those with ß-blocker therapy (P = .127).The present results indicate that a relationship exists between higher doses of furosemide and poor outcomes. The prognosis of HF patients with severe cardiac SNS abnormalities receiving high-dose short-acting loop diuretics is poor.

Humanized thymidine kinase-NOG mice can be used to identify drugs that cause animal-specific hepatotoxicity: a case study with furosemide.

Interspecies differences have limited the predictive utility of toxicology studies performed using animal species. A drug that could be a safe and effective treatment in humans could cause toxicity in animals, preventing it from being used in humans. We investigated whether the use of thymidine kinase (TK)-NOG mice with humanized livers could prevent this unfortunate outcome (i.e., "rescue" a drug for use in humans). A high dose of furosemide is known to cause severe liver toxicity in mice, but it is a safe and effective treatment in humans. We demonstrate that administration of a high dose of furosemide (200 mg/kg i.p.) causes extensive hepatotoxicity in control mice but not in humanized TK-NOG mice. This interspecies difference results from a higher rate of production of the toxicity-causing metabolite by mouse liver. Comparison of their survival curves indicated that the humanized mice were more resistant than control mice to the hepatotoxicity caused by high doses of furosemide. In this test case, humanized TK-NOG mouse studies indicate that humans could be safely treated with a high dose of furosemide.

Evaluation of the transporter-mediated herb-drug interaction potential of DA-9801, a standardized dioscorea extract for diabetic neuropathy, in human in vitro and rat in vivo.

BACKGROUND: Drug transporters play important roles in the absorption, distribution, and elimination of drugs and thereby, modulate drug efficacy and toxicity. With a growing use of poly pharmacy, concurrent administration of herbal extracts that modulate transporter activities with drugs can cause serious adverse reactions. Therefore, prediction and evaluation of drug-drug interaction potential is important in the clinic and in the drug development process. DA-9801, comprising a mixed extract of Dioscoreae rhizoma and Dioscorea nipponica Makino, is a new standardized extract currently being evaluated for diabetic peripheral neuropathy in a phase II clinical study. METHOD: The inhibitory effects of DA-9801 on the transport functions of organic cation transporter (OCT)1, OCT2, organic anion transporter (OAT)1, OAT3, organic anion transporting polypeptide (OATP)1B1, OATP1B3, P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP) were investigated in HEK293 or LLC-PK1 cells. The effects of DA-9801 on the pharmacokinetics of relevant substrate drugs of these transporters were also examined in vivo in rats. RESULTS: DA-9801 inhibited the in vitro transport activities of OCT1, OCT2, OAT3, and OATP1B1, with IC50 values of 106, 174, 48.1, and 273 µg/mL, respectively, while the other transporters were not inhibited by 300 µg/mL DA-9801. To investigate whether this inhibitory effect of DA-9801 on OCT1, OCT2, and OAT3 could change the pharmacokinetics of their substrates in vivo, we measured the pharmacokinetics of cimetidine, a substrate for OCT1, OCT2, and OAT3, and of furosemide, a substrate for OAT1 and OAT3, by co-administration of DA-9801 at a single oral dose of 1,000 mg/kg. Pre-dose of DA-9801 5 min or 2 h prior to cimetidine administration decreased the Cmax of cimetidine in rats. However, DA-9801 did not affect the elimination parameters such as half-life, clearance, or amount excreted in the urine, suggesting that it did not inhibit elimination process of cimetidine, which is governed by OCT1, OCT2, and OAT3. Moreover, DA-9801 did not affect the pharmacokinetic characteristics of furosemide, as evidenced by its unchanged pharmacokinetic parameters. CONCLUSION: Inhibitory effects of DA-9801 on OCT1, OCT2, and OAT3 observed in vitro may not necessarily translate into in vivo herb-drug interactions in rats even at its maximum effective dose.

Interaction of five anthraquinones from rhubarb with human organic anion transporter 1 (SLC22A6) and 3 (SLC22A8) and drug-drug interaction in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Rhubarb is a well-known traditional Chinese medicine and has been used in China for thousands of years. Anthraquinone derivatives including rhein, emodin, aloe-emodin, chrysophanol and physcion are the important components in rhubarb. MATERIALS AND METHODS: Here we studied the interaction of five anthraquinone derivatives with human renal organic anion transporter 1 (hOAT1) and hOAT3 stably expressed in cells, and interaction of rhein or rhubarb extract (RE) with furosemide (FS, substrate of OATs) in rats. RESULTS: Uptake of 6-carboxyl fluorescein via hOAT1 and fluorescein via hOAT3 were markedly inhibited by rhein, emodin and aloe-emodin, and slightly inhibited by chrysophanol and physcion. The estimated IC50 values for rhein, emodin, aloe-emodin and probenecid (typical inhibitor of hOAT1 and hOAT3) were 0.23, 0.61, 2.29 and 18.34 µM for hOAT1, and 0.08, 1.22, 5.37 and 5.83 µM for hOAT3, respectively. Furthermore, the data from the cellular accumulation assay indicated that these five compounds were not substrates of hOAT1 or hOAT3. Pharmacokinetic interaction between rhein and FS in rats showed that area under the curve (AUC0-t) for FS was increased by 65% when coadministrated with rhein. RE was also used to interact with FS in rats and results showed that AUC0-t of FS was increased by 32% and by 52% when coadministrated with single-dose or multiple-dose of RE, respectively. CONCLUSIONS: These findings suggested that five anthraquinones inhibited hOAT1 and hOAT3, but these compounds were not transported by hOAT1 or hOAT3. Furthermore, rhein or RE, might cause drug-drug interaction when coadministrated with substrates of OAT1 or OAT3 in vivo.

Microencapsulation of self-microemulsifying system: improving solubility and permeability of furosemide.

The primary goal of this study was to formulate Ca-pectinate microcapsules with self-microemulsifying core to enhance the solubility and permeability of BCS class IV drug furosemide. An Inotech IE-50R encapsulator equipped with a concentric nozzle was utilized to transform liquid self-microemulsifying system (SMES) to solid microcapsules. Self-microemulsifying core was optimized with respect to drug loading capacity and encapsulation efficiency and evaluated for its impact on furosemide permeability through rat small intestine and Caco-2 cell monolayers. Retention of the core phase was considerably improved (up to 70-80%) by optimization of the SMES and microcapsules' drying process. Incorporation of furosemide in self-microemulsifying core of microcapsules resulted in improved permeability and drug release characteristics in comparison to microspheres (without SMES in the core). The obtained results illustrate the prospective use of microcapsules with self-microemulsifying core for the delivery of compounds with poor biopharmaceutical properties via the oral route.

Development and in vitro evaluation of furosemide transdermal formulations using experimental design techniques.

The in vitro skin permeation of furosemide, a commonly used loop diuretic, through human epidermis, as a preliminary step towards the development of a transdermal therapeutic system, was examined. A screening study was carried out, in order to estimate the effects of the type, the concentration of enhancer and the concentration of gelling agent on the cumulative amount of furosemide permeated through human epidermis, using a 3(3) factorial design. The type and the concentration of enhancer were further evaluated as they were found to affect significantly furosemide permeation. In order to further increase the amount of the drug permeated, the combination of two enhancers, Azone and oleyl alcohol, at three concentration levels was employed, using an optimization technique. The results indicated that higher amounts of furosemide permeated were observed when Azone was used at 5.0-6.5% (v/v) and oleyl alcohol at 7.5-9% (v/v), in the gels used. These formulations seem to be suitable for possible transdermal delivery of furosemide for pediatric use.

The effect of hypoxaemia on drug disposition in chronic respiratory failure.

OBJECTIVE: The influence of hypoxaemia on the disposition of two common drugs has been examined in ten adults with stable chronic respiratory failure. METHODS: There were two experimental periods in this cross-over study: during these periods supplemental oxygen was either withheld or administered to impose clinical hypoxaemia or maintain normoxaemia, respectively. Each participant received either oral (40 mg) or intravenous (20 mg) frusemide combined with oral paracetamol (500 mg) on consecutive days of the two experimental periods. RESULTS: The total (bound plus unbound) plasma clearance of frusemide during hypoxaemia (arterial oxygen tension, PaO2 < or = 50 Torr) was not significantly different from the value during normoxaemia (PaO2 > or = 60 Torr) [76.9 and 62.4 ml.min-1]. The volume of distribution was not affected by acute hypoxaemia (121 ml.kg-1 without and 109 ml.kg-1 with oxygen; P > 0.05). Renal and non-renal clearances of frusemide were similar during the period of hypoxaemia (31 and 38 ml.min-1, respectively) compared to respective values during supplemental oxygen delivery (29 and 32 ml.min-1). The absolute bioavailability of frusemide during hypoxaemia (0.62) was not different to that obtained during normoxaemia (0.56). The combined sodium and potassium excretion rate (expressed as a function of the frusemide excretion rate) was not altered by changing the oxygen tension. The pharmacokinetics of paracetamol were unaffected by hypoxaemia.

Torasemide in advanced renal failure.

In patients with advanced renal failure, high doses of loop diuretics are required to promote negative sodium and water balance and to treat hypertension. Torasemide is a new loop diuretic that has a high bioavailability of 90% and a plasma half-life of 3-5 hours, which remains unchanged in chronic renal failure. Even in patients with advanced renal failure, intravenous and oral high-dose torasemide proves effective in increasing fluid and sodium excretion in a dose-dependent manner. A number of studies in renal failure patients provide evidence that, on a weight-by-weight basis, the ratio of diuretic potency between torasemide and furosemide is 1:2.5 after oral dosing and 1:1 after intravenous administration. The lack of a substantial calciuretic effect of torasemide in chronic renal disease needs further confirmation. Two controlled multicenter clinical trials comparing high oral doses of furosemide and torasemide in patients with end-stage renal disease requiring maintenance hemodialysis demonstrated a substantial increase in urinary volume and electrolyte excretions in patients receiving 100 or 200 mg oral torasemide once daily. A dose of 200 mg oral torasemide appears equally natriuretic to oral furosemide 500 mg, whereas the antihypertensive effect of torasemide is more pronounced. Neither torasemide nor furosemide in the above doses has a negative influence on the neurological status of hemodialysis patients.