Design of rapidly disintegrating oral tablets using acid-treated yeast cell wall: a technical note

Effect of excipients on oral absorption process according to the different gastrointestinal segments

INTRODUCTION

Excipients are necessary to develop oral dosage forms of any Active Pharmaceutical Ingredient (API). Traditionally, excipients have been considered inactive and inert substances, but, over the years, numerous studies have contradicted this belief. This review focuses on the effect of excipients on the physiological variables affecting oral absorption along the different segments of the gastrointestinal tract. The effect of excipients on the segmental absorption variables are illustrated with examples to help understand the complexity of predicting their in vivo effects.

AREAS COVERED

The effects of excipients on disintegration, solubility and dissolution, transit time, and absorption are analyzed in the context of the different gastrointestinal segments and the physiological factors affecting release and membrane permeation. The experimental techniques used to study excipient effects and their human predictive ability are reviewed.

EXPERT OPINION

The observed effects of excipient in oral absorption process have been characterized in the past, mainly in vitro (i.e. in dissolution studies, in vitro cell culture methods or in situ animal studies). Unfortunately, a clear link with their effects in vivo, i.e. their impact on Cmax or AUC, which need a mechanistic approach is still missing. The information compiled in this review leads to the conclusion that the effect of excipients in API oral absorption and bioavailability is undeniable and shows the need of implementing standardized and reproducible preclinical tools coupled with mechanistic and predictive physiological-based models to improve the current empirical retrospective approach.

Fabrication of Naftopidil-Loaded Tablets Using a Semisolid Extrusion-Type 3D Printer and the Characteristics of the Printed Hydrogel and Resulting Tablets

The production of three-dimensional (3D)-printed drugs holds promise for future personalized medicine. Here, we prepared tablets containing naftopidil as a model drug using a semisolid extrusion-type 3D bioprinter applicable for tissue engineering. A hydrogel is typically used as the printer ink for 3D bioprinters, and we incorporated various amounts of hydroxypropyl methylcellulose hydrogel (30%, 40%, and 50% gel) into the printer ink. The resulting 3D-printed gel product was dried to obtain tablets. The rheological properties of the printer ink changed as its composition was changed, and tablets were prepared successfully from several formulations. Increasing the amount of hydroxypropyl methylcellulose hydrogel in the printer ink led to delayed drug dissolution, decreased weight, and decreased hardness of the tablets. Delayed drug dissolution was also observed when the amount of disintegrating agent typically used in powder compression tablets was increased in the ink, and increasing the incorporated amount of the disintegrating agent crospovidone increased the hardness of the tablets. Our results will provide useful information for the preparation of tablets using semisolid extrusion-type 3D printers.

Orodispersible tablets: A new trend in drug delivery

The most common and preferred route of drug administration is through the oral route. Orodispersible tablets are gaining importance among novel oral drug-delivery system as they have improved patient compliance and have some additional advantages compared to other oral formulation. They are also solid unit dosage forms, which disintegrate in the mouth within a minute in the presence of saliva due to super disintegrants in the formulation. Thus this type of drug delivery helps a proper peroral administration in pediatric and geriatric population where swallowing is a matter of trouble. Various scientists have prepared orodispersible tablets by following various methods. However, the most common method of preparation is the compression method. Other special methods are molding, melt granulation, phase-transition process, sublimation, freeze-drying, spray-drying, and effervescent method. Since these tablets dissolve directly in the mouth, so, their taste is also an important factor. Various approaches have been taken in order to mask the bitter taste of the drug. A number of scientists have explored several drugs in this field. Like all other solid dosage forms, they are also evaluated in the field of hardness, friability, wetting time, moisture uptake, disintegration test, and dissolution test.