Development Of Oral Dosage Forms Research Articles

Recent Patents and Patented Technology Platforms for Pharmaceutical Taste Masking

Taste masking is an important factor in the development of oral dosage forms containing bitter active pharmaceutical ingredients. Currently numerous techniques are being applied to overcome this problem. Realizing this, several researchers and pharmaceutical companies are now engaged in developing novel techniques to address the problem of taste masking evident by numerous patents filed in this area in recent times. In this review the most recent patents for taste masking are discussed and how these patents overcome the limitations of conventional approaches of taste masking is also highlighted. Novel techniques based on some recent patents such as nanohybrid, melt extrusion, non-complex cyclodextrin compositions and off taste masking are providing new realms to taste masking of bitter drugs. The present article also provides an overview of various patented platform technologies based on different techniques/mechanisms employed for taste masking. The unique features and principles of taste-masking approaches used in various patented technologies are also discussed. A better understanding of these new patents and patented technologies will help researchers and pharmaceutical industries to select the appropriate platform, or to develop innovative products with improved taste masking properties.

The Dipeptide Monoester Prodrugs of Floxuridine and Gemcitabine—Feasibility of Orally Administrable Nucleoside Analogs

Dipeptide monoester prodrugs of floxuridine and gemcitabine were synthesized. Their chemical stability in buffers, enzymatic stability in cell homogenates, permeability in mouse intestinal membrane along with drug concentration in mouse plasma, and anti-proliferative activity in cancer cells were determined and compared to their parent drugs. Floxuridine prodrug was more enzymatically stable than floxuridine and the degradation from prodrug to parent drug works as the rate-limiting step. On the other hand, gemcitabine prodrug was less enzymatically stable than gemcitabine. Those dipeptide monoester prodrugs exhibited 2.4- to 48.7-fold higher uptake than their parent drugs in Caco-2, Panc-1, and AsPC-1 cells. Floxuridine and gemcitabine prodrugs showed superior permeability in mouse jejunum to their parent drugs and exhibited the higher drug concentration in plasma after in situ mouse perfusion. Cell proliferation assays in ductal pancreatic cancer cells, AsPC-1 and Panc-1, indicated that dipeptide prodrugs of floxuridine and gemcitabine were more potent than their parent drugs. The enhanced potency of nucleoside analogs was attributed to their improved membrane permeability. The prodrug forms of 5′-l-phenylalanyl-l-tyrosyl-floxuridine and 5′-l-phenylalanyl-l-tyrosyl-gemcitabine appeared in mouse plasma after the permeation of intestinal membrane and the first-pass effect, suggesting their potential for the development of oral dosage form for anti-cancer agents.

The development of orally administrable gemcitabine prodrugs with d-enantiomer amino acids: Enhanced membrane permeability and enzymatic stability

Gemcitabine prodrugs with d- and l-configuration amino acids were synthesized and their chemical stability in buffers, resistance to glycosidic bond metabolism, enzymatic activation, permeability in Caco-2 cells and mouse intestinal membrane, anti-proliferation activity in cancer cell were determined and compared to that of parent drug, gemcitabine. Prodrugs containing d-configuration amino acids were enzymatically more stable than ones with l-configuration amino acids. The activation of all gemcitabine prodrugs was 1.3–17.6-fold faster in cancer cell homogenate than their hydrolysis in buffer, suggesting enzymatic action. The enzymatic activation of amino acid monoester prodrugs containing d-configuration amino acids in cell homogenates was 2.2–10.9-fold slower than one of amino acid monoester prodrugs with l-configuration amino acids. All prodrugs exhibited enhanced resistance to glycosidic bond metabolism by thymidine phosphorylase compared to parent gemcitabine. Gemcitabine prodrugs showed superior the effective permeability in mouse jejunum to gemcitabine. More importantly, the high plasma concentration of d-amino acid gemcitabine prodrugs was observed more than one of l-amino acid gemcitabine prodrugs. In general, the 5′-mono-amino acid monoester gemcitabine prodrugs exhibited higher permeability and uptake than their parent drug, gemcitabine. Cell proliferation assays in AsPC-1 pancreatic ductal cell line indicated that gemcitabine prodrugs were more potent than their parent drug, gemcitabine. The transport and enzymatic profiles of 5′-d-valyl-gemcitabine and 5′-d-phenylalanyl-gemcitabine suggest their potential for increased oral uptake and delayed enzymatic bioconversion as well as enhanced uptake and cytotoxic activity in cancer cells, would facilitate the development of oral dosage form for anti-cancer agents and, hence, improve the quality of life for the cancer patients.

Dissolution media simulating the proximal canine gastrointestinal tract in the fasted state

Human biorelevant media have been shown to be a useful tool in pharmaceutical development and to provide input for in silico prediction of pharmacokinetic profiles after oral dosing. Dogs, in particular Beagles, are often used as animal models for preclinical studies. Key differences in the composition of human and canine gastric and intestinal fluids are described in the literature and underscore the need to develop a discrete set of biorelevant media, adapted to the conditions of the proximal canine gastrointestinal (GI) tract, to improve forecast and interpretation of preclinical results using in vitro dissolution studies. Canine biorelevant media can also be used in the development of oral dosage forms for companion animals, which is a rapidly growing market. The compositions of Fasted State Simulated Gastric Fluid canine (FaSSGFc) and Fasted State Simulated Intestinal Fluid canine (FaSSIFc) are adapted to the physiological composition of the corresponding gastrointestinal fluids in terms of pH, buffer capacity, osmolality, surface tension, as well as the bile salt, phospholipid, and free fatty acid content (in terms of concentration and reported subtypes). It was demonstrated that canine Fasted State Simulated Intestinal Fluid (FaSSIFc) is superior in predicting the solubility of model compounds in Canine Intestinal Fluid (CIF) compared to the human biorelevant media (FaSSIF and FaSSIF-V2). Two different versions of FaSSGFc, composed at pH 1.5 and pH 6.5, offer the possibility to design in vitro studies which correspond to the in vivo study design, depending on whether pentagastrin is used to decrease the gastric pH in the dogs or not. Canine biorelevant media can therefore be recommended to achieve more accurate forecasting and interpretation of pharmacokinetic studies of oral drug products in dogs.

Potential of Ordered Mesoporous Silica for Oral Delivery of Poorly Soluble Drugs

The use of ordered mesoporous silica is one of the more recent and rapidly developing formulation techniques for enhancing the solubility of poorly water-soluble drugs. Their large surface area and pore volume make ordered mesoporous silica materials excellent candidates for efficient drug loading and rapid release. While this new approach offers many promising advantages, further research is still necessary to elucidate the molecular mechanisms and to improve our scientific insight into the behavior of this system. In this review, the significant developments to date are presented and research challenges highlighted. Aspects of downstream processability are discussed in view of their special bulk powder properties and unique pore architecture. Lastly, perspectives for successful oral dosage form development are presented.

Coaxial Electrospray Formulations for Improving Oral Absorption of a Poorly Water-Soluble Drug

Development of oral dosage forms containing poorly water-soluble drugs is a major challenge in the pharmaceutical industry. This paper describes the use of coaxial electrospray deposition as a promising formulation technology for oral delivery of poorly water-soluble drugs. The technology produced core-shell particles composed of griseofulvin and poly(methacrylic acid-co-methyl methacrylate) (Eudragit L-100), with a diameter of around 1 μm. The drug phase was in an amorphous state when the griseofulvin core was coated with the Eudragit L-100 shell. The in vitro dissolution and in vivo oral absorption studies revealed that the core-shell formulation significantly improved dissolution and absorption behaviors, presumably because of a reduction in particle size, improvement in dispersity, and amorphization. Results demonstrated that coaxial electrospray deposition possesses great potential as novel formulation technology for enhancing oral absorption of poorly water-soluble drugs.

Evaluation of the impact of sodium lauryl sulfate source variability on solid oral dosage form development

Objective: The objective of this study was to investigate the effects of sodium lauryl sulfate (SLS) from different sources on solubilization/wetting, granulation process, and tablet dissolution of BILR 355 and the potential causes. Methods: The particle size distribution, morphology, and thermal behaviors of two pharmaceutical grades of SLS from Spectrum and Cognis were characterized. The surface tension and drug solubility in SLS solutions were measured. The BILR 355 tablets were prepared by a wet granulation process and the dissolution was evaluated. Results: The critical micelle concentration was lower for Spectrum SLS, which resulted in a higher BILR 355 solubility. During wet granulation, less water was required to reach the same end point using Spectrum than Cognis SLS. In general, BILR 355 tablets prepared with Spectrum SLS showed a higher dissolution than the tablets containing Cognis SLS. Micronization of SLS achieved the same improved tablet dissolution as micronized active pharmaceutical ingredient. Conclusions: The observed differences in wetting and solubilization were likely due to the different impurity levels in SLS from two sources. This study demonstrated that SLS from different sources could have significant impact on wet granulation process and dissolution. Therefore, it is critical to evaluate SLS properties from different suppliers, and then identify optimal formulation and process parameters to ensure robustness of drug product manufacture process and performance.

Aqueous Solubility Enhancement Through Engineering of Binary Solid Composites: Pharmaceutical Applications

Limits to the aqueous solubility of emerging new chemical entities, as well as older drug molecules, represent a barrier to solid oral dosage form development. Numerous techniques are conventionally employed in aqueous solubility enhancement, although a universal strategy has proven elusive. Formation of binary solid composites, such as eutectics or amorphous solid dispersions, offers an alternative to traditional solubility enhancement techniques. The reality of these systems, however, is that very few examples have been made commercially available, ultimately stemming from a lack of understanding regarding structural and thermodynamic stability-indicating phenomena associated with higher-energy solid materials. In the present work, a comprehensive structurally based review of the fundamental solid-state properties of binary composite materials is presented. Specific emphasis is placed on current topics of research in the area of binary composite formation and the relationship to the underutilization of this technology with the pharmaceutical industry.

A potentiometric titration method for the crystallization of drug-like organic molecules

It is generally accepted, that crystalline solids representing a low energy polymorph should be selected for development of oral dosage forms. As a consequence, efficient and robust procedures are needed at an early stage during drug discovery to prepare crystals from drug-like organic molecules. In contrast to the use of supersaturated solutions, we present a potentiometric crystallization procedure where saturated solutions are prepared in a controlled manner by pH-titration. Crystallization is carried out under defined conditions using the sample concentration and experimental p K a values as input parameters. Crystals of high quality were obtained for 11 drugs selected to demonstrate the efficiency and applicability of the new method. Technical improvements are suggested to overcome practical limitations and to enhance the possibility of obtaining crystals from molecules in their uncharged form.

Synthesis and evaluation of novel coumarin-based esterase-sensitive cyclic prodrugs of peptidomimetic RGD analogs with improved membrane permeability.

Earlier, we reported the development of a coumarin-based prodrug system that could be used for the preparation of cyclic prodrugs of opioid peptides. These cyclic prodrugs exhibited excellent membrane permeability characteristics. Therefore, it was of interest to determine the effects of this prodrug strategy on the membrane permeabilities of peptidomimetics which also have low membrane permeabilities. For this study, we have chosen two RGD (Arg-Gly-Asp) peptidomimetics, which have the potentials to be developed clinically as orally active antithrombotic agents. However, the clinical development of oral dosage forms of these RGD analogs has been hindered by their low intestinal mucosal permeability. Therefore, we have synthesized the corresponding coumarin-based cyclic prodrugs of these RGD peptidomimetics, which have the two most polar functional groups, a carboxyl and an amino group, masked as an ester and an amide, respectively. These cyclic prodrugs were shown to have higher membrane interaction potentials, as estimated by their partitioning between aqueous buffer and an immobilized artificial membrane, than the corresponding RGD analogs suggesting that they should exhibit good membrane permeation characteristics. Subsequently, in a separate study these cyclic prodrugs were shown to be 5 to 6-fold more able to permeate monolayers of Caco-2 cells, an in vitro cell culture model of the intestinal mucosa barrier, than the corresponding RGD peptidomimetics.

Development of oral dosage form for elderly patients: use of agar as base of rapidly disintegrating oral tablets.

Rapidly disintegrating tablets as an oral dosage form for elderly patients with impaired swallowing were investigated using agar powders (AG) or treated agar powders (TAG). When the compression pressure was changed from 0.4 to 2.0 ton/cm2, the disintegration time of AG tablets increased from about 60 to about 160s, and the hardness significantly increased from 3 to 13 kgw. The disintegration time and hardness of the TAG tablets were scarcely affected by the compression pressure: the disintegration time was 5--6s, and the hardness was 2--3 kgw. The rapid disintegration of the TAG tablets seemed due to the rapid water penetration into the tablet resulting from the large pore size and large overall pore volume. It was found that rapidly disintegrating oral tablets with proper hardness can be prepared using TAG.

Formulation development of an oral dosage form for an hiv protease inhibitor, AG1284

Several preformulation characteristics of a series of novel HIV protease inhibitors were examined as a prelude to expedient oral dosage form development. Initial studies indicated that these compounds were orally bioavailable in rats (≤ 39%), but chemically unstable at low pH. AG1284 was selected as the lead compound from the series for further preclinical development based on its relatively high oral bioavailability and stability. The pH-rate profiles of AG1284 indicated a first-order degradative loss of a dimethylbenzyl group under acidic conditions. Concentrated solutions of an amorphous form prepared in various pharmaceutical solvents exhibited precipitation on standing. The precipitate was identified as crystalline AG1284 by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and polarized light/hot stage microscopy, and its solubility in water proved to be much lower than that of the amorphous form. Oral administration in dogs of a solid blend of AG1284 with polyethylene glycol 3350 (PEG 3350) in enteric-coated hard gelatin capsules did not yield any detectable AG1284 levels in plasma. When dosed in a propylene glycol/water (60/40) solution at 50 mg/kg to rats, oral bioavailability and C max were 39% and 2.8 μg/ml, respectively. When delivered in a lyophilizable emulsion to rats at 100 mg/kg, oral bioavailability and C max were 31% and 3.0 μg/ml, respectively. The lyophilized product could be reconstituted with WFI to regenerate an emulsion.

An integrated approach to the selection of optimal salt form for a new drug candidate

A general method was developed to select the optimal salt form for BMS-180431, a novel HMG-CoA reductase inhibitor and a candidate for oral dosage form development, in an expeditious manner at the onset of the drug development process. The physicochemical properties such as hygroscopicity, physical stability of crystal forms at different humidity conditions, aqueous solubility, and chemical stability of seven salts e.g., sodium, potassium, calcium, zinc, magnesium, arginine and lysine, were studied using a multi-tier approach. The progression of studies among different tiers was such that the least time-consuming experiments were conducted earlier, thus saving time and effort. A ‘go/no go’ decision was made after each tier of testing the salts, thus avoiding generation of extensive data on all available salt forms. The hygroscopicities of all BMS-180431 salts were evaluated at tier 1 and four salts (sodium, potassium, calcium and zinc) were dropped from consideration due to excessive moisture uptake within the expected humidity range of pharmaceutical manufacturing plants (30–50% R.H. at ambient temperature). The remaining three salts were subjected to the tier 2 evaluation for any change in their crystal structures with respect to humidity and the determination of their aqueous solubilities in the gastrointestinal pH range. The magnesium salt was dropped from further consideration due to humidity-dependent changes in its crystal structure and low solubility in water (3.7 mg/ml at room temperature). Arginine and lysine salts, which were resistant to any change in their crystalline structures under extremes of humidity conditions (6 and 75% R.H.) and had high aqueous solubilities (> 200 mg/ml), were elevated to tier 3 for the determination of their chemical stability. Based on solid state stability of these two salts under accelerated conditions (temperature, humidity, and presence of excipients), consideration of ease of synthesis, ease of analysis, potential impurities, etc., and input from the marketing group with respect to its preference of counter ion species, the arginine salt was selected for further development. The number of tiers necessary to reach a decision on the optimal salt form of a compound may depend on the physicochemical properties studied and the number of salts available. This salt selection process can be completed within 4–6 weeks and be easily adopted in the drug development program.