Development and Validation a UPLC-MS/MS Method for Quantification of Pentoxifylline in Beagle Plasma: Application for Pharmacokinetic Study of Food Effect.

Purpose: To develop an UPLC-MS/MS method for the quantitative analysis of pentoxifylline in beagle dog plasma and apply it to a pharmacokinetic study of food effect. Methods: Sample separation was achieved using a Kinetex Phenyl-Hexyl column (50 × 2.1 mm, 1.7 µm) with a gradient elution program in 5.5 min after a simple protein precipitation with methanol. Using the mobile phase that made up by 0.2% formic acid and 5mM ammonium formate water (A) and methanol (B). Quantitation was carried out using the positive ionization mode with multiple reaction monitoring (MRM). A randomized, single-dose, two-period crossover study was conducted in six fasted or fed beagles that received 400 mg pentoxifylline sustained-release tablets (Brand name: Shuanling™, CSPC Pharmaceutical Group). WinNonlin® software was used to calculate pharmacokinetic parameters. Results: The linear calibration range was 2-1000 ng/mL (r2> 0.99). Both intra- and inter-batch precision were less than 6.27%, and the accuracy ranged from 88.65% to 97.18%. Pentoxifylline was readily absorbed in fasted and fed dogs administered a dose of 400 mg (tmax:1.54h vs 1.83h). Compared to the fasted group, the AUC0→t and Cmax in the fed group increased by 1.71-fold and 1.30-fold, respectively. In the fasted group, the AUC0→t and Cmax values were 4684.08 h•ng/mL and 2402.33 ng/mL, respectively. In the fed group, these values were 8027.75 h•ng/mL and 3119.67 ng/mL. The difference in AUC0-t between the fed and fasted group was statistically significant. Conclusion: The novel optimized UPLC-MS/MS assay is an effective tool for the determination of pentoxifylline and has been successfully applied in pharmacokinetic studies of pentoxifylline in beagle dogs. The administration of pentoxifylline sustained-release tablets with food significantly increased the area under the time curve, and it is recommended that they should be administered during or shortly after feeding.

Nanoparticulate tablet dosage form of lisofylline-linoleic acid conjugate for type 1 diabetes: in situ single-pass intestinal perfusion (SPIP) studies and pharmacokinetics in rat.

Lisofylline (LSF) is an anti-inflammatory molecule with high aqueous solubility and rapid metabolic interconversion to its parent drug, pentoxifylline (PTX) resulting in very poor pharmacokinetic (PK) parameters, necessitating high dose and dosing frequency. In the present study, we resolved the physicochemical and pharmacokinetic limitations associated with LSF and designed its oral dosage form as a tablet for effective treatment in type 1 diabetes (T1D). Self-assembling polymeric micelles of LSF (lisofylline-linoleic acid polymeric micelles (LSF-LA PLM)) were optimized for scale-up (6 g batch size) and lyophilized followed by compression into tablets. Powder blend and tablets were evaluated as per USP. LSF-LA PLM tablet so formed was evaluated for in vitro release in simulated biological fluids (with enzymes) and for cell viability in MIN-6 cells. LSF-LA PLM in tablet formulation was further evaluated for intestinal permeability (in situ) along with LSF and LSF-LA self-assembled micelles (SM) as controls in a rat model using single-pass intestinal perfusion (SPIP) study. SPIP studies revealed 1.8-fold higher oral absorption of LSF-LA from LSF-LA PLM as compared to LSF-LA SM and ~5.9-fold higher than LSF (alone) solution. Pharmacokinetic studies of LSF-LA PLM tablet showed greater Cmax than LSF, LSF-LA, and LSF-LA PLM. Designed facile LSF-LA PLM tablet dosage form has potential for an immediate decrease in the postprandial glucose levels in patients of T1D.

Improved Oral Pharmacokinetics of Pentoxifylline with Palm Oil and Capmul® MCM Containing Self-Nano-Emulsifying Drug Delivery System.

Pentoxifylline (PTX), an anti-hemorrhage drug used in the treatment of intermittent claudication, is extensively metabolized by the liver resulting in a reduction of the therapeutic levels within a short duration of time. Self-nano-emulsifying drug delivery system (SNEDDS) is well reported to enhance the bio-absorption of drugs by forming nano-sized globules upon contact with the biological fluids after oral administration. The present study aimed to formulate, characterize, and improve the oral bioavailability of PTX using SNEDDS. The formulated SNEDDS consisted of palm oil, Capmul® MCM, and Tween® 80 as oil, surfactant, and co-surfactant, respectively. The mixture design module under the umbrella of the design of experiments was used for the optimization of SNEDDS. The dynamic light-scattering technique was used to confirm the formation of nanoemulsion based on the globule size, in addition to the turbidity measurements. In vivo bioavailability studies were carried out on male Wistar rats. The pharmacokinetic parameters upon oral administration were calculated using the GastroPlus software. The optimized SNEDDS had a mean globule size of 165 nm with minimal turbidity in an aqueous medium. Bioavailability of PTX increased 1.5-folds (AUC = 1013.30 ng h/mL) as SNEDDS than the pure drug with an AUC of 673.10 ng h/mL. In conclusion, SNEDDS was seen to enhance the bioavailability of PTX and can be explored to effectively control the incidents of intermittent claudication.

Pharmacokinetics of pentoxifylline and its 5-hydroxyhexyl metabolite after intravenous administration of increasing doses to sheep.

OBJECTIVE: To determine the pharmacokinetics of pentoxifylline (PTX) and its 5-hydroxyhexyl metabolite (M-I) after IV administration of increasing doses of PTX to sheep. ANIMALS: 6 healthy adult Merino sheep. PROCEDURES: Each sheep received 10-, 20-, and 40-mg/kg doses of PTX, IV, with a 15-day washout period between doses. Blood samples were collected before and at predetermined times after administration of each dose to determine plasma PTX and M-I concentrations by high-performance liquid chromatography. Pharmacokinetic parameters for PTX and M-I were estimated by noncompartmental analysis. RESULTS: No adverse effects were observed after administration of the 10- and 20-mg/kg doses. Following administration of the 40-mg/kg dose, all sheep developed tachycardia and hypersalivation and appeared agitated for approximately 4 hours. Plasma PTX concentrations considered therapeutic in other species were achieved in all sheep after administration of all 3 doses. Pharmacokinetic parameters for PTX and M-I varied in a dose-dependent linear manner. For PTX, the mean area under the concentration-time curve (AUC), elimination half-life, and volume of distribution increased with dose and ranged from 15.67 to 94.66 h·µg/mL, 0.68 to 0.91 hours, and 0.55 to 0.66 L/kg, respectively, whereas clearance decreased with dose and ranged from 0.42 to 0.64 L/h/kg. The mean ratio of the AUC for M-I to AUC for PTX ranged from 0.38 to 0.46. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that pharmacokinetic parameters for PTX and M-I varied in a dose-dependent linear manner in healthy sheep. Further studies are warranted to determine the therapeutic threshold and optimal dosage for PTX in sheep.

Self-assembling lisofylline-fatty acid conjugate for effective treatment of diabetes mellitus.

Lisofylline is an anti-inflammatory agent with proven anti-diabetic activity. Its high solubility and rapid metabolism results in poor bioavailability and short half-life, limiting its clinical utility. We have synthesized Lisofylline-Linoleic acid (LSF-LA) conjugate which self-assembled into micelles (156.9 nm; PDI 0.187; CMC 1 µg/mL; aggregation number 54) without any surfactant and showed enhanced cellular uptake. It protected MIN6 insulinoma cells from cytokine induced cell death and enhanced insulin production under inflammatory conditions. It also suppressed the proliferation of activated peripheral blood mononuclear cells and reduced the production of inflammatory cytokines, IFN-γ and TNF-α. LSF-LA micelles exhibited reduced protein binding, significantly higher half-life (5.7-fold) and higher apparent volume of distribution (5.3-fold) than free LSF. In T1D animals, reduced blood glucose levels were observed at a reduced dose (~15 mg/kg, once daily of LSF-LA micelles vs. 25 mg/kg, twice daily of free LSF) that was further confirmed by immunohistochemical analysis.

Effects of maturation and size on population pharmacokinetics of pentoxifylline and its metabolites in very preterm infants with suspected late-onset sepsis or necrotizing enterocolitis: a pilot study incorporating clinical outcomes.

AIMS: Infection-induced inflammation is associated with adverse long-term outcomes in preterm infants. Pentoxifylline (PTX) is a candidate for adjunct immunomodulatory therapy in preterm infants with late-onset sepsis (LOS) and necrotizing enterocolitis (NEC), but pharmacokinetic data in this population are extremely limited. This study aims to characterize the pharmacokinetic properties of intravenous PTX and its metabolites in preterm infants. METHOD: An open label pilot clinical study of intravenous PTX as an adjunct therapy in preterm infants (gestation <32 weeks) with suspected LOS or NEC was undertaken. PTX was infused for 12 h for two days (60 mg kg-1 per 12 h), and in infants with confirmed diagnosis of LOS or NEC, for 6 h for another 4 days (30 mg kg-1 per 6 h). Plasma concentrations of PTX and its principal metabolites from collected blood samples were measured using a validated LCMS assay. NONMEM was used to analyse the data using population pharmacokinetic modelling. RESULTS: The preterm infants (n = 26) had a median (range) gestation of 24.8 weeks (23.3-30.4) and birthweight of 689 g (370-1285). PTX was well tolerated and without treatment-limiting adverse effects. Changes in size (weight) and maturation were successfully modelled for PTX and metabolites. After allometric scaling, clearance increased with postmenstrual age, increasing by approximately 30% per week for PTX and M1 (lisofylline) and simulations of current dosing demonstrated a six-fold difference in exposure between 24 and 35 weeks postmenstrual age. CONCLUSIONS: The developed model can be used to explore dosing strategies based on size and maturation for preterm infants.

Pharmacokinetics of pentoxifylline and its 5-hydroxyhexyl metabolite following intravenous administration in cattle.

This study investigated the pharmacokinetics of pentoxifylline (PTX) and its 5-hydroxyhexyl metabolite (M-I) after single-dose intravenous (IV) administration (10 mg/kg) of PTX in six healthy cattle. The safety of PTX was evaluated by clinical observation and biochemical analysis. Plasma concentrations of PTX and M-I were simultaneously determined by reverse-phase high performance liquid chromatography. Pharmacokinetic parameters were calculated using non-compartmental methods. Salivation and discomfort were observed for 2 h following the drug administration. Serum direct bilirubin, total bilirubin, and phosphorus levels at 24 h following the drug administration were significantly different from the control values (0 h) (P < 0.05). Pharmacokinetic variables of PTX were characterized by a short terminal elimination half-life (1.05 ± 0.19 h), a large volume of distribution (6.30 ± 1.76 L/kg), and high total body clearance (5.31 ± 1.27 L/h/kg). The mean ratio between the area under the concentration-time curves of M-I and PTX was 1.34. These results indicate that single-dose administration of PTX at 10 mg/kg IV in cattle resulted in therapeutic concentrations similar to those observed in humans and horse. However, further studies are necessary to determine the safety and pharmacokinetics following repeated administrations of PTX.

Development and validation of bioanalytical liquid chromatography-tandem mass spectrometry method for the estimation of pentoxifylline in human plasma: Application for a comparative pharmacokinetic study.

A method for bioanalysis of pentoxifylline in human plasma was developed using liquid chromatography-tandem mass spectrometry, which is simple, specific, and sensitive. Pentoxifylline D5 was used as the internal standard. Employing only 100 µl of human plasma, processing was done with solid-phase extraction technique. The analyte and the internal standard were separated from endogenous components on Ace phenyl column using a mixture of 5 mM ammonium acetate buffer and high performance liquid chromatography grade acetonitrile (60:40, v/v) as mobile phase at a flow rate of 1 ml/min. The linearity of the method was in the range of 3-1200 ng/ml with r2 > 0.99. Positive ion MRM mode was used for the detection of the analyte and the internal standard. The method was validated as per the US Food and Drug Administration guidelines and the results were within the acceptance limits. The proposed method was applied for comparative pharmacokinetic study of pentoxifylline after oral administration of 400 and 600 mg tablets to South Indian male subjects under fed conditions.

Influence of inflammatory disorders on pharmacokinetics of lisofylline in rats: implications for studies in humans.

1. Despite the number of favourable properties of lisofylline (LSF), clinical trials on this compound have not yielded the expected results yet. 2. The aims of this study were to evaluate the pharmacokinetics of LSF enantiomers in rats following intravenous, oral and subcutaneous administration of (±)-LSF and to assess the influence of experimental inflammatory disorders, such as multiple organ dysfunction syndrome and severe sepsis on LSF pharmacokinetics. 3. In addition, based on the results obtained an attempt was made to elucidate the possible reasons for the failure of LSF therapy in clinical trials carried out in patients with severe inflammatory disorders. 4. A subcutaneous route of (±)-LSF administration to rats is more favourable than an oral one due to a high bioavailability and a fast absorption of both LSF enantiomers. Pharmacokinetics of LSF in rats is significantly influenced by inflammatory diseases. Too low LSF serum levels might have been one of the reasons for clinical trial failures. A long-term i.v. infusion of LSF seems to be more effective compared to short-term multiple infusions that were used in clinical trials, as it may provide concentrations above IC50 for inhibition of both TNF-alpha release and cAMP degradation in serum for a longer period of time.

Enhanced anticancer efficacy of histone deacetyl inhibitor, suberoylanilide hydroxamic acid, in combination with a phosphodiesterase inhibitor, pentoxifylline, in human cancer cell lines and in-vivo tumor xenografts.

Vorinostat [suberoylanilide hydroxamic acid (SAHA)], a histone deacetylase inhibitor, shows limited clinical activity against solid tumors when used alone. The methyl xanthine drug, pentoxifylline (PENT), has been described to have antitumor properties. The aim of this study was to look for the enhanced anticancer activities of both agents when used in combination at doses lower than their respective efficacy dose when used alone. We investigated the antitumor potential of this novel combination in vitro and in vivo. The combination index was assessed for these two drugs to look for synergistic antiproliferative activity against a broad spectrum of human cancer cell lines. Consistent additive to synergistic interactions were observed in HCT116 cells when PENT was combined with SAHA at all drug tested concentrations. The combination of SAHA and PENT induces chromatin condensation and apoptosis downstream of the pan histone deacetylase inhibition and phosphodiesterase regulation, leading to subsequent cell cycle arrest at their lower tested concentrations. Further, the ability of this combination to inhibit angiogenesis, both in vitro and in vivo, was examined and a significant inhibition in tube formation in HUVEC cells and neovascularization of Matrigel plug was observed. A significant inhibition in tumor growth was observed in severe combined immunodeficient mice bearing HCT116 (colon) and PC3 (prostate) human xenografts treated with SAHA (30 mg/kg, intraperitoneal) in combination with PENT (60 mg/kg, intraperitoneal), with no loss in body weight and 100% survival. In conclusion, these findings indicate the enhanced anticancer activity of SAHA in combination with PENT both in vitro and in vivo.

Simultaneous estimation of lisofylline and pentoxifylline in rat plasma by high performance liquid chromatography-photodiode array detector and its application to pharmacokinetics in rat.

Lisofylline (LSF) is an anti-inflammatory and immunomodulatory agent with proven activity in serious infections associated with cancer chemotherapy, hyperoxia-induced acute lung injury, autoimmune disorders including type-1 diabetes (T1DM) and islet rejection after islet transplantation. It is also an active metabolite of another anti-inflammatory agent, Pentoxifylline (PTX). LSF bears immense therapeutic potential in multiple pharmacological activities and hence appropriate and accurate quantification of LSF is very important. Although a number of analytical methods for quantification of LSF and PTX have been reported for pharmacokinetics and metabolic studies, each of these have certain limitations in terms of large sample volume required, complex extraction procedure and/or use of highly sophisticated instruments like LC-MS/MS. The aim of current study is to develop a simple reversed-phase HPLC method in rat plasma for simultaneous determination of LSF and PTX with the major objective of ensuring minimum sample volume, ease of extraction, economy of analysis, selectivity and avoiding use of instruments like LC-MS/MS to ensure a widespread application of the method. A simple liquid-liquid extraction method using methylene chloride as extracting solvent was used for extracting LSF and PTX from rat plasma (200µL). Samples were then evaporated, reconstituted with mobile phase and injected into HPLC coupled with photo-diode detector (PDA). LSF, PTX and 3-isobutyl 1-methyl xanthine (IBMX, internal standard) were separated on Inertsil® ODS (C18) column (250×4.6mm, 5µm) with mobile phase consisting of A-methanol B-water (50:50v/v) run in isocratic mode at flow rate of 1mL/min for 15min and detection at 273nm. The method showed linearity in the concentration range of 50-5000ng/mL with LOD of 10ng/mL and LLOQ of 50ng/mL for both LSF and PTX. Weighted linear regression analysis was also performed on the calibration data. The mean absolute recoveries were found to be 80.47±3.44 and 80.89±3.73% for LSF and PTX respectively. The method was successfully applied for studying the pharmacokinetics of LSF and PTX after IV bolus administration at dose of 25mg/kg in Wistar rat. In conclusion, a simple, sensitive, accurate and precise reversed-phase HPLC-UV method was established for simultaneous determination of LSF and PTX in rat plasma.

A First-in-Patient, Multicenter, Double-Blind, 2-Arm, Placebo-Controlled, Randomized Safety and Tolerability Study of a Novel Oral Drug Candidate, CTP-499, in Chronic Kidney Disease.

The prevalence of chronic kidney disease (CKD) related to type 2 diabetes is increasing worldwide. In addition to standard of care, treatment with anti-inflammatory and antifibrotic agents such as CTP-499, a novel oral, multisubtype selective inhibitor of phosphodiesterases, may be important in CKD treatment. A phase 1b randomized, double-blind, placebo-controlled clinical trial of CTP-499 in CKD patients (25 active, 8 placebo) with an estimated glomerular filtration rate of 30-59 mL/min/1.73 m(2) was conducted to assess safety and tolerability. Secondary outcomes included pharmacokinetics and exploratory effects on inflammatory and hematology markers. Patients received 600 mg CTP-499 or matching placebo tablets orally once daily for 2 weeks, then twice daily for 2 additional weeks. CTP-499 was well tolerated with no serious or severe adverse events, or adverse events leading to discontinuation. CTP-499 was rapidly absorbed and produced acceptable interpatient variability. Of the 5 metabolites (M1-M5), M5 was the most abundant in plasma and urine. Exposure to CTP-499 and metabolites was higher in CKD patients than previously reported in healthy volunteers. No statistically significant differences were detected between the CTP-499- and placebo-treated groups for any of the biomarkers tested. This study provides data supporting further evaluation of CTP-499 in CKD patients.

Microemulsion for topical application of pentoxifylline: In vitro release and in vivo evaluation.

Microemulsion containing pentoxifylline was developed and characterized for use as a topical alternative to treat skin disorders. The transparent formulation was developed and optimized based on a pseudoternary phase diagram. Pentoxifylline-loaded microemulsion (PTX-ME) was composed of 44% Tween 80™/Brij 52™ mix as surfactants (S), 51% of caprylic/capric triglycerides as the oil phase (O) and 5% of water as aqueous phase (A). It was classified as an isotropic water-in-oil (W/O) system with droplets that had a heterogeneous spherical shape within the nanosized range (67.36±8.90nm) confirmed by polarized light microscopy, differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. In vitro studies using static diffusion Franz cells revealed that the release of PTX from ME followed the Higuchi kinetic model. Topical PTX-ME application developed superior anti-inflammatory activity when compared to the PTX solution, reducing the paw edema up to 88.83%. Our results suggested that this colloidal nanosystem is a promising agent for the delivery of pentoxifylline, increasing its ability to modulate the inflammatory aspects of skin disorders.

Optimization of elastic transfersomes formulations for transdermal delivery of pentoxifylline.

Pentoxifylline (PTX) is a xanthine derivative indicated in treatment of intermittent claudication and chronic occlusive arterial diseases. It has low oral bioavailability and short half-life; thus, it was considered as a good candidate drug for the transdermal transfersomes formulation. In the present study, an attempt has been made for development, in-vitro and in-vivo evaluation of transdermal transfersomes using sodium cholate (SC) and non-ionic surfactants as edge activators. The optimal formulation, F4(Gcholate), exhibited drug entrapment efficiency of 74.9±1.6%, vesicles elasticity of 145±0.6 (mgs(-1)cm(-2)), zeta potential of -34.9±2.2mV, average vesicle diameter of 0.69±0.049µm with PDI of 0.11±0.037 and permeation flux of 56.28±0.19µgcm(-2)h(-1). It attained a prolonged drug release where 79.1±2.1% of PTX released after 10h of the run. The drug release kinetic obeys Higuchi model (R(2)=0.997) with Fickian diffusion mechanism. Moreover, the formula enhanced drug permeation through the excised rat's skin predominantly via the carrier-mediated mechanism by 9.1 folds in comparison with the control. Results of the in vivo pharmacokinetics study in male volunteers showed that F4(Gcholate) transfersomes formulation increased PTX absorption and prolonged its half-life comparing to the commercial oral SR tablets. Hence, the elastic transfersomes formulation of PTX possesses admirable potential to avoid drug metabolism, improve PTX bioavailability and sustain its release.

Development of PEGylated solid lipid nanoparticles of pentoxifylline for their beneficial pharmacological potential in pathological cardiac hypertrophy.

OBJECTIVE: The present study was designed to develop PEGylated solid lipid nanoparticles (SLNs) of pentoxifylline (with increased t½) for the management of cardiac hypertrophy. MATERIALS AND METHODS: PEGylated SLNs were prepared by melt emulsification method and characterised by zeta potential, polydispersity index, entrapment efficiency, in vitro release and pharmacokinetic profile. Hypertrophy was assessed as increase in tumour necrosis factor-alpha, mean arterial blood pressure, LV protein content and left ventricular end diastolic pressure. RESULT: PEGylated SLNs (F19) with increased t½ were developed and characterised. F19 attenuates hypertrophy assessed in terms of parameters employed. CONCLUSION: Thus, PEGylated SLNs (F19) of pentoxifylline have enhanced t½ and consequently more significantly preclude cardiac hypertrophy as compared to pentoxifylline.

Physiologically based modeling of lisofylline pharmacokinetics following intravenous administration in mice.

Lisofylline (LSF), is the R-(-) enantiomer of the metabolite M1 of pentoxifylline, and is currently under development for the treatment of type 1 diabetes. The aim of the study was to develop a physiologically based pharmacokinetic (PBPK) model of LSF in mice and to perform simulations in order to predict LSF concentrations in human serum and tissues following intravenous and oral administration. The concentrations of LSF in serum, brain, liver, kidneys, lungs, muscle, and gut were determined at different time points over 60 min by a chiral HPLC method with UV detection following a single intravenous dose of LSF to male CD-1 mice. A PBPK model was developed to describe serum pharmacokinetics and tissue distribution of LSF using ADAPT II software. All pharmacokinetic profiles were fitted simultaneously to obtain model parameters. The developed model characterized well LSF disposition in mice. The estimated intrinsic hepatic clearance was 5.427 ml/min and hepatic clearance calculated using the well-stirred model was 1.22 ml/min. The renal clearance of LSF was equal to zero. On scaling the model to humans, a good agreement was found between the predicted by the model and presented in literature serum LSF concentration-time profiles following an intravenous dose of 3 mg/kg. The predicted LSF concentrations in human tissues following oral administration were considerably lower despite the twofold higher dose used and may not be sufficient to exert a pharmacological effect. In conclusion, the mouse is a good model to study LSF pharmacokinetics following intravenous administration. The developed PBPK model may be useful to design future preclinical and clinical studies of this compound.

Uroprotective effect of pentoxifylline in cyclophosphamide-induced hemorrhagic cystitis in rats.

The role of phosphodiesterase inhibitor, pentoxifylline, in the prevention of cyclophosphamide-induced hemorrhagic cystitis was evaluated in a rat model. Hemorrhagic cystitis was induced in rats by an intraperitoneal (i.p.) injection of a single dose of cyclophosphamide (150 mg/kg). Pentoxifylline (150 mg/kg/day/ip) was administered for 10 days followed by cyclophosphamide. Hemorrhagic cystitis was well characterized macroscopically, microscopically, and biochemically. Cyclophosphamide induced bladder injury including acute severe inflammation, vascular congestion, severe edema, hemorrhage, inflammatory cell infiltration in the lamina propria, and epithelial denudation; as well as it notably elevated serum inflammatory cytokines (tumor necrosis factor-α, interleukin-6, and interleukin-1ß), bladder content of malondialdehyde and total nitrate, accompanied with depletion of bladder antioxidant enzymes activities (glutathione peroxidase, superoxide dismutase, glutathione-S-transferase, and catalase). Prior administration of pentoxifylline improved all biochemical and histologic alterations induced by the cytotoxic drug cyclophosphamide. In conclusion, pentoxifylline has proven uroprotective efficacy in the cyclophosphamide-induced hemorrhagic cystitis model, possibly through modulating the release of inflammatory cytokines and nitric oxide and restoring the oxidant/antioxidant balance.

Pharmacokinetics of pentoxifylline and its main metabolites in patients with different degrees of heart failure following a single dose of a modified-release formulation.

Pentoxifylline (PTX) is extensively metabolized in the body, and all its 3 plasma metabolites (M1, M4, M5) are pharmacologically active. The authors evaluated the pharmacokinetics of PTX and its metabolites in 20 patients with chronic heart failure (CHF). Eleven had moderate and 9 severe CHF. The time courses of PTX, M1, M4, and M5 plasma levels were determined after oral administration of a sustained-release 600-mg tablet of PTX, and for each compound, AUC, maximal plasma concentration (C(max)), and time to C(max) (T(peak)) were calculated. Compared with patients with moderate CHF, those with severe CHF showed a significant delay in T(peak) of PTX (3.9 vs 1.6 hours) and M5 (5.6 vs 3.6 hours), a 59% significant increase in M5 AUC, and a 56% nonsignificant increase in PTX AUC. In the whole population, the AUCs of PTX, M4, and M5 were inversely correlated with markers of liver function, whereas the AUCs of M4 and M5 were inversely correlated with the creatinine clearance. In view of the kinetic features of slow-release formulations (flip-flop phenomenon), the delay in T(peak) of PTX in patients with severe CHF compared with moderate CHF should be ascribed to a reduced elimination rate.

Ex vivo percutaneous absorption of ketamine, bupivacaine, diclofenac, gabapentin, orphenadrine, and pentoxifylline: comparison of versatile cream vs. reference cream.

This ex vivo human percutaneous absorption study evaluated a set of six model drugs (ketamine hydrochloride, bupivacaine hydrochloride, diclofenac sodium, gabapentin, orphenadrine citrate, pentoxifylline) from two popular formulations for topically applied compounding preparations. The compounded preparations used in this study were Versatile cream and a reference cream. Each formulation was applied to human trunk skin mounted on Franz Diffusion Cells, 50 mg/chamber (or 28.2 mg/cm2). Serial dermal receiver solutions were collected for 48 hours. Analysis of the resultant data supports the concept that the Versatile base formulation provides improved characteristics relative to the reference base. This is of key importance where the patient does not show clinical improvement when a conventional topical delivery vehicle is used in the formulation. From the results, it is reasonable to anticipate that, relative to the reference formulation, the Versatile formulation provides enhanced transdermal delivery of some analgesic medications.