The rectal route is an effective route for the local and systemic delivery of active pharmaceutical ingredients. The environment of the rectum is relatively constant with low enzymatic activity and is favorable for drugs having poor oral absorption, extensive first-pass metabolism, gastric irritation, stability issues in the gastric environment, localized activity, and for drugs that cannot be administered by other routes. The present review addresses the rectal physiology, rectal diseases, and pharmaceutical factors influencing rectal delivery of drugs and discusses different rectal drug delivery systems including suppositories, suspensions, microspheres, nanoparticles, liposomes, tablets, and hydrogels. Clinical trials on various rectal drug delivery systems are presented in tabular form. Applications of different novel drug delivery carriers viz. nanoparticles, liposomes, solid lipid nanoparticles, microspheres, transferosomes, nano-niosomes, and nanomicelles have been discussed and demonstrated for their potential use in rectal administration. Various opportunities and challenges for rectal delivery including recent advancements and patented formulations for rectal drug delivery have also been included.

One of the important parameters in the case of dosage form is taste. Most of the drugs available in oral dosage form have an unpleasant taste which leads to patient incompliance and affects the success ratio of products in market. Geriatric and paediatric patients suffer more with a bitter taste of medicines. According to the studies reported, it is found that 50% of the population have problem of swallowing tablets, especially the pediatric and geriatric population. Masking the taste of bitter drugs has become necessary in the pharmaceutical field and increasing interest of researchers to develop various methods for masking the bitter taste of drugs. Five major tastes that are felt by our tongue are salt, sour, sweet, bitter and umami. When the drug dissolves with saliva, drug molecules interact with taste receptors present on the tongue and give taste sensations. Although many solid oral dosage forms like pills, tablets have additional advantage of masking and encapsulation of bitter taste drugs but they might not be effective for children because they may or may not swallow pills or tablets. There are various other methods that masks the bitter taste of drugs such as addition of sweeteners and flavouring agents, granulation, coating, inclusion complexes, extrusion method, ion-exchange resins etc, discussed in first section of article. The second part of this article consists of various nanotechnology-based drug delivery systems that were fabricated by researchers to mask the bitter taste of drugs. A brief of recent literature on various nanocarriers that were fabricated or developed for taste masking has been discussed in this part. A better understanding of these methods will help researchers and pharmaceutical industries to develop novel drug delivery systems with improved taste masking properties.

Introduction: Etoricoxib is a BCS class II drug with poor aqueous solubility and analgesic and anti-inflammatory properties. Complexation with cyclodextrins is one of the widely used methods, amongst others, for enhancing the solubility and bioavailability of drugs. In current research work, inclusion complexes of etoricoxib using modified forms of cyclodextrin, i.e., captisol were prepared using kneading, evaporation, and freeze-drying methods to improve the solubility and dissolution characteristics. Methods: Etoricoxib inclusion complexes (ratio 1:1) were formulated using kneading, evaporation, and freeze-drying methods. The formulated inclusion complexes were evaluated for phase solubility, equilibrium solubility studies, Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, differential scanning calorimetry studies, in vitro drug release, similarity factor and in vivo studies. Results: The freeze-drying method produced inclusion complexes with the highest equilibrium solubility (ten times that of the pure drug). Fourier transform infrared spectroscopy studies showed no drug-polymer interaction. Differential scanning calorimetry and scanning electron microscopy studies suggested the incorporation of the drug into inclusion complexes of cyclodextrin. In vitro dissolution studies of kneading, evaporation and freeze-drying method inclusion complexes showed 66.53%, 79.13% and 88% drug release, respectively, in 3h, whereas pure drug exhibited 61.77% drug release in 3 h. The f1 value obtained was less than 50, which is indicative of a significant difference in release characteristics of kneading, evaporation and freeze-drying methods with that of the marketed formulation. In vivo studies indicated that inclusion complexes formulated by the freeze-drying method showed better analgesic and anti-inflammatory effects in comparison to formulations prepared by kneading and evaporation methods. Conclusion: It is concluded that the formulation prepared by the freeze-drying method led to a significant enhancement of dissolution and solubility rate of etoricoxib in comparison to the formulation prepared by the kneading method and evaporation method.