Poloxamer 188 and propylene glycol-based rectal suppository enhances anticancer effect of 5-fluorouracil in mice

Formulation of oxybutynin chloride microparticle-loaded suppositories: in vitro characterization and in vivo pharmacokinetic study

Background

Oxybutynin chloride (OXC) is used to treat overactive urinary bladder. OXC is metabolized in the liver to N-desethyloxybutynin, which is mainly responsible for the anticholinergic side effects of OXC. Conventional oxybutynin suppositories formulated earlier have shown most common side effects, such as dry mouth, constipation and serious anticholinergic reaction. Hence the present research work deals with the formulation and characterization of OXC microparticle-loaded mucoadhesive suppositories which may remain adhered in the lower rectum and avoid first pass metabolism. The emulsification–ionic gelation method is employed to prepare OXC microparticles. Two formulation factors at three levels, i.e. polymer concentration and stirring speed, were selected. Sodium alginate (concentration 1–2%) and 1% w/v Carbopol 971P were used to prepare OXC microparticles. OXC microparticles were evaluated for various parameters such as production yield, entrapment efficiency, mucoadhesive strength, shape, size, zeta potential, Fourier Transform Infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, in vitro dissolution studies and stability studies. Suppositories loaded with OXC microparticles were prepared by the fusion method using Poloxamer 188 and propylene glycol and evaluated for various parameters like weight variation, disintegration time, in vitro dissolution study, stability study and pharmacokinetic study.

Results

Results of in vitro characterization revealed that optimized batch of OXC loaded microparticles exhibited production yield 94.024% entrapment efficiency 95.378% and mucoadhesion strength 95.544%, particle size range 764.04–894.13 µm, zeta potential − 14.5 mV, with 0.946 desirability. Consequences of DSC and XRPD evaluation shown that drug was effectively entrapped inside the microparticles. In vitro release studies revealed improvement in drug dissolution as a consequence of its entrapment into microparticles. SEM results showed that micelles were sphere-shaped. On rectal administration of OXC microparticles loaded suppository in male Sprague–Dawley Rats, the relative bioavailability was found 173.72%.

Conclusion

In vivo study elicits rapid increase in absorption of drug from microparticles loaded suppository when compared with the oral formulation and drug loaded suppository in rats. OXC microparticles loaded suppository is novel and promising drug delivery system for rectal administration and may avoid anticholinergic side effects of hepatic metabolite, N-desethyloxybutynin. These rectal drug delivery systems will be advantageous for efficient absorption of drugs and to avoid first pass metabolism.

Thermosensitive hydrogels for local delivery of 5-fluorouracil as neoadjuvant or adjuvant therapy in colorectal cancer

Spurred by high risk for local tumor recurrence and non-specific toxicity of systemic chemotherapy, clinicians have recently granted a growing interest to locoregional therapeutic strategies. In this perspective, we recently developed a multipurpose thermosensitive hydrogel based on reversible thermogelling properties of poloxamers P407 and P188, a bioadhesive excipient and antineoplastic effect of 5-fluorouracil (5-FU) for the local treatment of colorectal cancer (CRC) in ectopic CT26 murine models. Antitumor efficacy was assessed in mice following intratumoral (IT) injection mimicking neoadjuvant therapy and subcutaneous (SC) application after tumor excision simulating adjuvant therapy. Rheological characterization disclosed that P407/P188/alginate 20/2/1% w/v thermosensitive hydrogel is an injectable free-flowing solution at ambient temperature that undergoes a SOL-GEL transition at 26.0 °C ± 0.6 °C and thereby forms in situ a non-flowing gel at physiological temperature. The generated gel presented an elastic behavior and responded according to a shear-thinning fluid upon shear rate. Although delayed by the addition of alginate 1% w/v, 5-FU is released mainly by diffusion mechanism. The local delivery of 5-FU from P407/P188/alginate/5-FU 20/2/1/0.5% w/v hydrogel in the preclinical tumor models led to a significant tumor growth delay. These results demonstrated that poloxamer-based thermosensitive hydrogels provide a simple and efficient means for local chemotherapeutics delivery.

In situ delivery of thermosensitive gel-mediated 5-fluorouracil microemulsion for the treatment of colorectal cancer

In situ administration of 5-fluorouracil (5FU) “thermosensitive” gel effectively reduced systemic side effects in treating colon rectal cancer; however, the penetration efficacy of the formulation was considerably low due to the poor lipid solubility of 5FU. The aim of this study was to develop thermosensitive gel-mediated 5FU water-in-oil microemulsion (TG-5FU-ME) for improving the infiltration of 5FU. An in vitro release test showed that TG-5FU-ME sustained the drug’s release up to 10 hours. TG-5FU-ME exhibited good stability, and the microemulsion entrapped did not show any change in morphology and 5FU content during the 4-month storage. Transportation test in the Caco-2 cell monolayer showed that TG-5FU-ME had a permeability 6.3 times higher than that of 5FU thermosensitive gel, and the intracellular uptake of 5FU increased by 5.4-fold compared to that of 5FU thermosensitive gel. In vivo tissue distribution analysis exhibited that the TG-5FU-ME group had drug levels in rectal tissue and mesenteric lymph nodes, which were significantly higher than those of 5FU thermosensitive gel group, with very low blood levels of 5FU in both groups. Furthermore, TG-5FU-ME was not associated with detectable morphological damage to the rectal tissue. Conclusively, TG-5FU-ME might be an efficient rectal delivery system to treat colorectal cancer.

Evaluation of epirubicin in thermogelling and bioadhesive liquid and solid suppository formulations for rectal administration

Temperature sensitive Pluronic (Plu) and pH-sensitive polyacrylic acid (PAA) were successfully mixed in different ratios to form in situ gelling formulations for colon cancer therapy. The major formulations were prepared as the liquid and solid suppository dosage forms. Epirubicin (Epi) was chosen as a model anticancer drug. In vitro characterization and in vivo pharmacokinetics and therapeutic efficacy of Epi in six Plu/PAA formulations were evaluated. Our in vitro data indicate that Epi in Plu 14%/PAA 0.75% of both solid and liquid suppositories possess significant cytotoxicity, strong bioadhesive force, long-term appropriate suppository base, sustained release, and high accumulation of Epi in rat rectums. These solid and liquid suppositories were retained in the upper rectum of Sprague-Dawley (SD) rats for at least 12 h. An in vivo pharmacokinetic study using SD rats showed that after rectal administration of solid and liquid suppositories, Epi had greater area under the curve and higher relative bioavailability than in a rectal solution. These solid and liquid suppositories exhibited remarkable inhibition on the tumor growth of CT26 bearing Balb/c mice in vivo. Our findings suggest that in situ thermogelling and mucoadhesive suppositories demonstrate a great potential as colon anticancer delivery systems for protracted release of chemotherapeutic agents.

In vitro biocompatibility of thermally gelling liquid mucoadhesive loaded curcuminoids in colorectal cancer chemoprevention

PURPOSE

Colorectal cancer (CRC) is the third leading cause of cancer death in Taiwan; it ranks top three in the cancer mortality rate. Curcuminoids are derived from the rhizome of Curcuma longa. It has shown anti-cancer activity and apoptosis induction in a variety of cancer cell lines. This aims to study the potential of Poloxamer 407 as the thermogelling and mucoadhesive polymer for development of a site-targeting delivery system to enhance the localized delivery of curcuminoids to the colorectal cells for CRC chemotherapy.

METHODS

The mucoadhesive strength and rheological properties were measured as a function of poloxamer loaded with curcuminoids.

RESULTS

The gelation temperature of Poloxamer 407 was found to vary with its concentration and start gelling at 37°C at the concentration of 15.5% (w/v). To ensure gelation at physiological temperature after intra-rectal application, gelation temperature was determined by rheological measurement as well as by its physical appearance. The results indicated that its mucoadhesive strength also shows a dependency on temperature, which appears to be related to the increment in the maximum strength and average strength of the polymer.

CONCLUSION

The results have suggested that Poloxamer 407 could be a potential thermogelling and mucoadhesive polymer for the development of a site-targeting colorectal drug delivery system for curcuminoids in colorectal cancer therapy.