A novel method for the preclinical assessment of rectal irritation

Characterisation of rectal amoxicillin (RAMOX) for the treatment of pneumonia in children

Access to medicines, including their availability and affordability, is a major public health challenge worldwide. This research aimed to characterise rectal formulations containing amoxicillin for the treatment of pneumonia in children under five, as an accessible alternative to existing formulations. Lipophilic Suppocire (S-NA15) and hydrophilic polyethylene glycol (PEG; 80% PEG 1500 and 20% PEG 4000, w/w) suppositories containing 250 mg amoxicillin were prepared. Hardness, apparent viscosity, uniformity of mass, uniformity of content, disintegration and dissolution time were determined. Irritation potential was screened using a slug mucosal assay and antibacterial efficacy against Staphylococcus aureus determined by isothermal microcalorimetry. Both lipophilic and hydrophilic formulations met the European Pharmacopoeia standards for suppositories when tested in vitro. They disintegrated within 30 min with rapid amoxicillin release profiles (98.6 ± 0.9%, 94.9 ± 1.2% over 30 min, respectively). Over-encapsulation of S-NA15 suppositories with hydroxypropyl methylcellulose shells slowed drug release and improved stability over 2 months. S-NA15 suppositories were classified as non-irritant and PEG suppositories only mildly irritant. Antibacterial efficacy of formulations was equivalent to amoxicillin alone. Both PEG and over-encapsulated S-NA15 rectal formulations developed in the present work have shown promise based on pre-clinical screening, and further development is justified to develop a product with commercial potential.

Nonvascular drug-eluting stent coated with sodium caprate-incorporated polyurethane for the efficient penetration of paclitaxel into tumor tissue

To increase the therapeutic potency of nonvascular drug-eluting stents, sodium caprate was employed as a drug-penetration enhancer. A polytetrafluoroethylene-covered drug-eluting stent was coated with a mixture containing sodium caprate, paclitaxel, and polyurethane via the rolling coating technique. The coated stent has a smooth membrane surface with a 40-µm membrane thickness. Paclitaxel was released from the coated stent for two months. In the multilayered cell sheet model, sodium caprate in the polyurethane membrane (PUSC10) showed the possibility of enhancing the paclitaxel tissue penetration. The amount of penetrated paclitaxel for the sodium caprate-containing polyurethane membrane (PUSC10) was two times higher than that of sodium caprate-free polyurethane membrane. Additionally, the potential of sodium caprate was confirmed by a tumor-bearing small animal model. PUSC10 incorporated with Nile red (as a model fluorescence dye for visualization of drug penetration; PUSC10–Nile red) or PUSC10 incorporated with paclitaxel (PUSC10–paclitaxel) membrane was implanted at tumor sites in Balb/c mice. In the case of PUSC10–Nile red, the tissue penetration depth of Nile red was significantly increased from 30 µm (without sodium caprate) to 1060 µm (with sodium caprate). After seven days, an almost four times higher therapeutic area of PUSC10–paclitaxel was observed compared to that of polyurethane–paclitaxel (without sodium caprate) by a terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The results indicate that sodium caprate improves the penetration and therapeutic efficiencies of drugs in drug-eluting stents, and thus, it has potential for local stent therapy.

Formulation and delivery of anti-HIV rectal microbicides: advances and challenges

Men and women engaged in unprotected receptive anal intercourse (RAI) are at higher risk of acquiring HIV from infected partners. The implementation of preventive strategies is urgent and rectal microbicides may be a useful tool in reducing the sexual transmission of HIV. However, pre-clinical and first clinical trials have been able to identify limitations of candidate products, mostly related with safety issues, which can in turn enhance viral infection. Indeed, the development of suitable formulations for the rectal delivery of promising antiretroviral drugs is not an easy task, and has been mostly based on products specifically intended for vaginal delivery, but these have been shown to provide sub-optimal outcomes when administered rectally. Research and development in the rectal microbicide field are now charting their own path and important information is now available. In particular, specific formulation requirements of rectal microbicide products that need to be met have just recently been acknowledged despite additional work being still required. Desirable rectal microbicide product features regarding characteristics such as pH, osmolality, excipients, dosage forms, volume to be administered and the need for applicator use have been studied and defined in recent years, and specific guidance is now possible. This review provides a synopsis of the field of rectal microbicides, namely past and ongoing clinical studies, and details on formulation and drug delivery issues regarding the specific development of rectal microbicide products. Also, future work, as required for the advancement of the field, is discussed.

Safety and efficacy of sodium caprate in promoting oral drug absorption: from in vitro to the clinic

A major challenge in oral drug delivery is the development of novel dosage forms to promote absorption of poorly permeable drugs across the intestinal epithelium. To date, no absorption promoter has been approved in a formulation specifically designed for oral delivery of Class III molecules. Promoters that are designated safe for human consumption have been licensed for use in a recently approved buccal insulin spray delivery system and also for many years as part of an ampicillin rectal suppository. Unlike buccal and rectal delivery, oral formulations containing absorption promoters have the additional technical hurdle whereby the promoter and payload must be co-released in high concentrations at the small intestinal epithelium in order to generate significant but rapidly reversible increases in permeability. An advanced promoter in the clinic is the medium chain fatty acid (MCFA), sodium caprate (C(10)), a compound already approved as a food additive. We discuss how it has evolved to a matrix tablet format suitable for administration to humans under the headings of mechanism of action at the cellular and tissue level as well as in vitro and in vivo efficacy and safety studies. In specific clinical examples, we review how C(10)-based formulations are being tested for oral delivery of bisphosphonates using Gastro Intestinal Permeation Enhancement Technology, GIPET (Merrion Pharmaceuticals, Ireland) and in a related solid dose format for antisense oligonucleotides (ISIS Pharmaceuticals, USA).