Bioavailability and tissular distribution of docetaxel, a P-glycoprotein substrate, are modified by interferon-alpha in rats

Achievements in Thermosensitive Gelling Systems for Rectal Administration

Rectal drug delivery is an effective alternative to oral and parenteral treatments. This route allows for both local and systemic drug therapy. Traditional rectal dosage formulations have historically been used for localised treatments, including laxatives, hemorrhoid therapy and antipyretics. However, this form of drug dosage often feels alien and uncomfortable to a patient, encouraging refusal. The limitations of conventional solid suppositories can be overcome by creating a thermosensitive liquid suppository. Unfortunately, there are currently only a few studies describing their use in therapy. However, recent trends indicate an increase in the development of this modern therapeutic system. This review introduces a novel rectal drug delivery system with the goal of summarising recent developments in thermosensitive liquid suppositories for analgesic, anticancer, antiemetic, antihypertensive, psychiatric, antiallergic, anaesthetic, antimalarial drugs and insulin. The report also presents the impact of various types of components and their concentration on the properties of this rectal dosage form. Further research into such formulations is certainly needed in order to meet the high demand for modern, efficient rectal gelling systems. Continued research and development in this field would undoubtedly further reveal the hidden potential of rectal drug delivery systems.

LC478, a Novel Di-Substituted Adamantyl Derivative, Enhances the Oral Bioavailability of Docetaxel in Rats

P-glycoprotein (P-gp)-mediated efflux of docetaxel in the gastrointestinal tract mainly impedes its oral chemotherapy. Recently, LC478, a novel di-substituted adamantyl derivative, was identified as a non-cytotoxic P-gp inhibitor in vitro. Here, we assessed whether LC478 enhances the oral bioavailability of docetaxel in vitro and in vivo. LC478 inhibited P-gp mediated efflux of docetaxel in Caco-2 cells. In addition, 100 mg/kg of LC478 increased intestinal absorption of docetaxel, which led to an increase in area under plasma concentration-time curve (AUC) and absolute bioavailability of docetaxel in rats. According to U.S. FDA criteria (I, an inhibitor concentration in vivo tissue)/(IC₅₀, inhibitory constant in vitro) >10 determines P-gp inhibition between in vitro and in vivo. The values 15.6–20.5, from (LC478 concentration in intestine, 9.37–12.3 μM)/(IC₅₀ of LC478 on P-gp inhibition in Caco-2 cell, 0.601 μM) suggested that 100 mg/kg of LC478 sufficiently inhibited P-gp to enhance oral absorption of docetaxel. Moreover, LC478 inhibited P-gp mediated efflux of docetaxel in the ussing chamber studies using rat small intestines. Our study demonstrated that the feasibility of LC478 as an ideal enhancer of docetaxel bioavailability by P-gp inhibition in dose (concentration)-dependent manners.

Enhancing Docetaxel Delivery to Multidrug-Resistant Cancer Cells with Albumin-Coated Nanocrystals

Intravenous delivery of poorly water-soluble anticancer drugs such as docetaxel (DTX) is challenging due to the low bioavailability and the toxicity related to solubilizing excipients. Colloidal nanoparticles are used as alternative carriers, but low drug loading capacity and circulation instability limit their clinical translation. To address these challenges, DTX nanocrystals (NCs) were prepared using Pluronic F127 as an intermediate stabilizer and albumin as a functional surface modifier, which were previously found to be effective in producing small and stable NCs. We hypothesize that the albumin-coated DTX NCs (DTX-F-alb) will remain stable in serum-containing medium so as to effectively leverage the enhanced permeability and retention effect. In addition, the surface-bound albumin, in its native form, may contribute to cellular transport of NCs through interactions with albumin-binding proteins such as secreted protein acidic and rich in cysteine (SPARC). DTX-F-alb NCs showed sheet-like structure with an average length, width, and thickness of 284 ± 96, 173 ± 56, and 40 ± 8 nm and remained stable in 50% serum solution at a concentration greater than 10 μg/mL. Cytotoxicity and cellular uptake of DTX-F-alb and unformulated (free) DTX were compared on three cell lines with different levels of SPARC expression and DTX sensitivity. While the uptake of free DTX was highly dependent on DTX sensitivity, DTX-F-alb treatment resulted in relatively consistent cellular levels of DTX. Free DTX was more efficient in entering drug-sensitive B16F10 and SKOV-3 cells than DTX-F-alb, with consistent cytotoxic effects. In contrast, multidrug-resistant NCI/ADR-RES cells took up DTX-F-alb more than free DTX with time and responded better to the former. This difference was reduced by SPARC knockdown. The high SPARC expression level of NCI/ADR-RES cells, the known affinity of albumin for SPARC, and the opposing effect of SPARC knockdown support that DTX-F-alb have exploited the surface-bound albumin-SPARC interaction in entering NCI/ADR-RES cells. Albumin-coated NC system is a promising formulation for the delivery of hydrophobic anticancer drugs to multidrug-resistant tumors.

Enhancing biopharmaceutical performance of an anticancer drug by long chain PUFA based self-nanoemulsifying lipidic nanomicellar systems

The aim of this study was to develop polyunsaturated fatty acid (PUFA) long chain glyceride (LCG) enriched self-nanoemulsifying lipidic nanomicelles systems (SNELS) for augmenting lymphatic uptake and enhancing oral bioavailability of docetaxel and compare its biopharmaceutical performance with a medium-chain fatty acid glyceride (MCG) SNELS. Equilibrium solubility and pseudo ternary phase studies facilitated the selection of suitable LCG and MCG. The critical material attributes (CMAs) and critical process parameters (CPPs) were earmarked using Placket-Burman Design (PBD) and Fractional Factorial Design (FFD) for LCG- and MCG-SNELS respectively, and nano micelles were subsequently optimized using I- and D-optimal designs. Desirability function unearthed the optimized SNELS with T_emul <5min, D_nm <100nm, Rel_15min >85% and Perm_45min >75%. The SNELS demonstrated efficient biocompatibility and energy dependent cellular uptake, reduced P-gp efflux and increased permeability using bi-directional Caco-2 model. Optimal PUFA enriched LCG-SNELS exhibited distinctly superior permeability and absorption parameters during ex vivo permeation, in situ single pass intestinal perfusion, lymphatic uptake and in vivo pharmacokinetic studies over MCG-SNELS.

Surface-modified solid lipid nanoparticles for oral delivery of docetaxel: enhanced intestinal absorption and lymphatic uptake

Docetaxel is a potent anticancer drug, but development of an oral formulation has been hindered mainly due to its poor oral bioavailability. In this study, solid lipid nanoparticles (SLNs) surface-modified by Tween 80 or D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS 1000) were prepared and evaluated in terms of their feasibility as oral delivery systems for docetaxel. Tween 80-emulsified and TPGS 1000-emulsified tristearin-based lipidic nanoparticles were prepared by a solvent-diffusion method, and their particle size distribution, zeta potential, drug loading, and particle morphology were characterized. An in vitro release study showed a sustained-release profile of docetaxel from the SLNs compared with an intravenous docetaxel formulation (Taxotere®). Tween 80-emulsified SLNs showed enhanced intestinal absorption, lymphatic uptake, and relative oral bioavailability of docetaxel compared with Taxotere in rats. These results may be attributable to the absorption-enhancing effects of the tristearin nanoparticle. Moreover, compared with Tween 80-emulsified SLNs, the intestinal absorption and relative oral bioavailability of docetaxel in rats were further improved in TPGS 1000-emulsified SLNs, probably due to better inhibition of drug efflux by TPGS 1000, along with intestinal lymphatic uptake. Taken together, it is worth noting that these surface-modified SLNs may serve as efficient oral delivery systems for docetaxel.

Docetaxel-loaded thermosensitive liquid suppository: optimization of rheological properties

The main purpose of this work was to optimize the rheological properties of docetaxel (DCT)-loaded thermosensitive liquid suppositories for rectal administration. DCT-loaded liquid suppositories were prepared by a cold method and characterized in terms of physicochemical and viscoelastic properties. Major formulation parameters including poloxamer (P407) and Tween 80 were optimized to adjust the thermogelling and mucoadhesive properties for rectal administration. Notably, the gel strength and mucoadhesive force significantly increased with the increase in these variables. Furthermore, DCT incorporation did not alter the viscoelastic behavior, and the mean particle size of nanomicelles in it was approximately 16 nm with a distinct spherical shape. The formulation existed as liquid at room temperature and transformed into gel at physiological temperature through the reverse gelation phenomenon. Thus, DCT-loaded thermosensitive liquid suppositories [DCT/P407/P188/Tween 80 (0.25/11/15/10 %)] with optimal gel properties were easy to prepare and administer rectally, and might enable the gel to stay in the rectum without getting out from rectum.

Docetaxel-loaded thermosensitive and bioadhesive nanomicelles as a rectal drug delivery system for enhanced chemotherapeutic effect

PURPOSE

To investigate the potential of thermosensitive and biadhesive nanomicelles in improving the bioavailability of docetaxel (DCT) and its chemotherapeutic effect.

METHOD

DCT-loaded nanomicelles were prepared by emulsufication and characterized in terms of physico-chemical and visco-elastic parameters. The optimzed formulation was evaluated for in vivo localization, pharmacokinetic and anti-tumor efficacy.

RESULTS

The hydrodynamic size of DCT-loaded nanomicelles was approximately 13 nm and the nanomicelles exhibited a sufficient gelation strength (9250 mPa·s) and bioadhesive force (2100 dyn/cm²) to be retained in the upper part of rectum. We observed a high rectal bioavailability of 29% DCT compared to that following oral administration in rats, as it successfully evaded the multidrug efflux transporters and hepatic first-pass metabolism. Plasma concentration around ∼50 ng/mL was maintained throughout the study period (12 h) while Taxotere® attained subtherapeutic range within 4 h of drug administration. Results also revealed that the rectally administered DCT-loaded nanomicelles exhibited a significant anti-tumor effect (200 mm³) with a reduced toxicity profile when compared to orally administered DCT (950 mm³). Furthermore, histological study showed that the rectal mucosa was completely intact with no signs of irritation upon treatment with DCT-loaded nanomicelles.

CONCLUSIONS

Taken together, our novel thermosensitive and biadhesive nanomicelles demonstrated the ability to improve the bioavailability and chemotherapeutic potential of DCT in vivo. To the best of our knowledge, this is the first report describing the rectal delivery of DCT-loaded nanomicelles.

Pluronic P105/F127 mixed micelles for the delivery of docetaxel against Taxol-resistant non-small cell lung cancer: optimization and in vitro, in vivo evaluation

The aim of this work was to establish a novel polymeric mixed micelle composed of Pluronic P105 and F127 copolymers loaded with the poorly soluble antitumor drug docetaxel (DTX) against Taxol-resistant non-small cell lung cancer. A central composite design was utilized to optimize the preparation process, helping to improve drug solubilization efficiency and micelle stability. Prepared by a thin-film hydration method, the average size of the optimized mixed micelle was 23 nm, with a 92.40% encapsulation ratio and a 1.81% drug-loading efficiency. The optimized formulation showed high storage stability in lyophilized form, with 95.7% of the drug content remaining after 6 months’ storage at 4°C. The in vitro cytotoxicity assay showed that the IC50 values for Taxotere^® and mixed micelles were similar for A549, while on A549/Taxol cell lines, DTX-loaded P105/F127 mixed micelles showed a superior hypersensitizing effect; their IC50 value (0.059 μg/mL) was greatly reduced compared to those of Taxotere injections (0.593 μg/mL). The in vivo pharmacokinetic study showed that the mixed-micelle formulation achieved a 1.85-fold longer mean residence time in circulation and a 3.82-fold larger area under the plasma concentration-time curve than Taxotere. In addition, therapeutic improvement of mixed micelles in vivo against A549/Taxol was obtained. The tumor inhibition rate of the micelles was 69.05%, versus 34.43% for Taxotere (P < 0.01). Therefore, it could be concluded from the results that DTX-loaded P105/F127 mixed micelles might serve as a potential antitumor drug delivery system to overcome multidrug resistance in lung cancer.

Interferon-alpha improves docetaxel antitumoral and antimetastatic efficiency in Lewis lung carcinoma bearing mice

AIMS

Interferon-alpha (IFN-α) was shown to reduce P-glycoprotein (P-gp) expression and activity in several tissues. The purpose of this study was to evaluate the impact of IFN-α pretreatment on the antitumoral and antimetastatic, Docetaxel (DTX, P-gp substrate), on Lewis Lung Cancer (3LL) bearing mice and to correlate it to DTX pharmacokinetics.

MAIN METHODS

Six groups of C57/Bl6 mice received subcutaneous (s.c.) 2.10(6) 3LL cells, then IFN-α 4MIU/kg for 7days, then received or did not receive i.v. or oral DTX (30mg/kg). Pharmacokinetic studies were done on a part of the mice: DTX concentrations were assessed in plasma and tumors, where AUC were estimated with the Bailer method, and half-lives and MRT were determined with a non-compartmental analysis. Tumor growth was assessed more than 21days: animals were then sacrificed and lung metastases number was counted. Kaplan-Meier analysis was made to analyze survival data during the survey period.

KEY FINDINGS

DTX i.v. associated with IFN-α significantly improved mouse survival (19.6±0.6days vs. 17.1±0.8days for control mice, p=0.047) with greater antimetastatic effects (87.5% reduction in the number of metastases compared to control mice). The effect on tumor growth was not modified within the IFN-α/DTX i.v. treated groups when compared to mice receiving DTX i.v. alone. The pharmacokinetic analysis showed an increase of DTX concentrations in tumors at 30min after DTX i.v. administration and an increase in the oral bioavailability of orally given DTX following an IFN-α treatment.

SIGNIFICANCE

Our study established that IFN-α increases DTX uptake in tumors, improves its antitumoral efficiency and improves animals' survival.

Enhanced oral bioavailability of docetaxel by lecithin nanoparticles: preparation, in vitro, and in vivo evaluation

The aim of this research work was to investigate the potential of lecithin nanoparticles (LNs) in improving the oral bioavailability of docetaxel. Docetaxel-loaded LNs (DTX-LNs) were prepared from oil-in-water emulsions and characterized in terms of morphology, size, zeta potential, and encapsulation efficiency. The in vitro release of docetaxel from the nanoparticles was studied by using dialysis bag method. Caco-2 cell monolayer was used for the in vitro permeation study of DTX-LNs. Bioavailability studies were conducted in rats and different pharmacokinetic parameters were evaluated after oral administration of DTX-LNs. The results showed that DTX-LNs had a mean diameter of 360 ± 8 nm and exhibited spherical shape with smooth surface under transmission electron microscopy. The DTX-LNs showed a sustained-release profile, with about 80% of docetaxel released within 72 hours. The apical to basolateral transport of docetaxel across the Caco-2 cell monolayer from the DTX-LNs was 2.14 times compared to that of the docetaxel solution (0.15 × 10⁻⁵ ± 0.016 × 10⁻⁵ cm/second versus 0.07 × 10⁻⁵ ± 0.003 × 10⁻⁵ cm/second). The oral bioavailability of the DTX-LNs was 3.65 times that of docetaxel solution (8.75% versus 2.40%). These results indicate that DTX-LNs were valuable as an oral drug delivery system to enhance the absorption of docetaxel.

Immunological response as a source to variability in drug metabolism and transport

Through the last decades it has become increasingly evident that disease-states involving cytokines affect the pharmacokinetics of drugs through regulation of expression and activity of drug metabolizing enzymes, and more recently also drug transporters. The clinical implication is however difficult to predict, since these effects are dependent on the degree of inflammation and may be changed when the diseases are treated. This article will give an overview of the present understanding of the effects of cytokines on cytochrome P450 enzymes and drug transporters, and highlight the importance of considering these issues in regard to increasing use of the relatively new class of drugs, namely therapeutic proteins.

Effects of morin on the pharmacokinetics of docetaxel in rats with 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors

Docetaxel is a P-glycoprotein (P-gp) substrate and metabolized via cytochrome P450 (CYP) 3A subfamily in rats. Morin is an inhibitor of both CYPs and P-gp. Hence, the effects of morin on the intravenous and oral pharmacokinetics of docetaxel were investigated using 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumor rats (DMBA rats) as an animal model of human breast cancer. Docetaxel was administered intravenously (4 mg/kg) and orally (20 mg/kg) without and with morin (15 mg/kg) in DMBA rats. After the intravenous administration of docetaxel in control and DMBA rats with and without morin, the values of non-renal clearance and area under the plasma concentration-time (AUC) for docetaxel were comparable. Morin did not increase AUC or the absolute oral bioavailability (F) for docetaxel after the oral administration of docetaxel in control and DMBA rats with and without morin. The inhibition of hepatic and intestinal metabolism of docetaxel by morin and/or DMBA and the effect of intestinal P-gp inhibition by morin on the pharmacokinetics of docetaxel did not seem to be considerable in DMBA-induced mammary tumor rats.

Effect of interferon-alpha treatment on [68Ga-DOTA,Tyr3,Thre8]octreotide uptake in CA20948 tumors: a small-animal PET study

In peptide receptor radionuclide therapy of neuroendocrine tumors, improvements have been made by increasing the affinity for receptors and by protecting critical organs (e.g., kidneys). However, tumor parameters involved in radiopeptide uptake are still under investigation. Interferon-α (IFNα) is used as biotherapy for neuroendocrine tumors. Several mechanisms of action are described, but the potential effect of IFNα on tumor uptake of labeled peptide has not been studied in vivo yet.

METHODS

Twenty-six male CA20948 tumor-bearing Lewis rats were imaged before and during IFNα treatment using quantitative small-animal PET with [(68)Ga-DOTA,Tyr(3),Thre(8)]octreotide. Imaging was performed at days 0, 3, and 7. Animals were divided into 3 groups according to the treatment: control (injected daily with saline), half (4 d of IFNα treatment from day 0 to day 3, then saline), and full (7 d of IFNα). A daily dose of IFNα (1.5 mIU) was administered subcutaneously. Quantitative PET results are expressed as percentage injected dose per cm(3) and normalized to baseline (day 0) values. Tumor size was monitored by PET and caliper measurements.

RESULTS

Gross tumor uptake and tumor volumes increased in all groups over the 7-d period. On day 3, mean ± SD ratios to day 0 were 1.2 ± 0.2, 1.3 ± 0.5, and 1.2 ± 0.4, respectively, for control, half, and full groups. On day 7, respective values were 1.1 ± 0.2, 1.3 ± 0.6, and 1.5 ± 0.4. At day 3, a comparison among groups showed no statistically significant difference. At day 7, the full group showed a significantly higher ratio in activity concentration than the control group (P = 0.021). A good correlation was found between tumor volumes assessed by small-animal PET and caliper measurements (R = 0.89, P < 0.0001).

CONCLUSION

As expected, over a period of 7 d, both tumor volumes and radiopeptide uptake increased in all animals. However, the activity concentration increased significantly more at day 7 in animals treated for 7 d with IFNα, compared with controls. This is the first, to our knowledge, in vivo indication that IFNα is able to increase tumor uptake of the labeled analog in a small-animal model of neuroendocrine tumors. The mechanisms underlying this effect (flow, vascular permeability, receptor upregulation) remain unknown and need to be further investigated.

Effects of tesmilifene, a substrate of CYP3A and an inhibitor of P-glycoprotein, on the pharmacokinetics of intravenous and oral docetaxel in rats

OBJECTIVES

It has been reported that docetaxel is a P-glycoprotein substrate and is metabolized via the cytochrome P450 (CYP) 3A subfamily in rats. Tesmilifene is a substrate of the CYP3A subfamily and is an inhibitor of P-glycoprotein. Thus, the effects of various doses of tesmilifene on the pharmacokinetics of intravenous and orally administered docetaxel have been investigated in rats.

METHODS

Docetaxel (20 mg/kg as base) was administered intravenously and orally without and with tesmilifene (5, 10, and 20 mg/kg) in rats.

KEY FINDINGS

After intravenous administration of docetaxel with tesmilifene, the values of nonrenal clearance (CL(NR)) and area under the plasma concentration-time (AUC) for docetaxel were comparable with those without tesmilifene. Tesmilifene did not increase the values of AUC or of absolute oral bioavailability (F) for docetaxel after oral administration of docetaxel with tesmilifene.

CONCLUSIONS

The inhibition for the metabolism of docetaxel via hepatic and intestinal CYP3A subfamily, and inhibition of P-glycoprotein-mediated efflux of docetaxel in the intestine by tesmilifene were almost negligible. The extremely low value of F for docetaxel was due to the incomplete absorption from the gastrointestinal tract and considerable first-pass metabolism of docetaxel in rats.