Abstract: Most of the drugs that have been invented are of BCS Class II. Therefore, dissolution rate enhancement is the key aspect for absorption of these drugs. Liquisolid technology is very efficient in the dissolution rate enhancement of these drugs. Moreover, use of other polymers such as Eudragit and hydroxypropyl methylcellulose in the liquisolid approach can cause sustained release of drugs. This review focuses on the formulation approaches of liquisolid tablets or compacts along with its fundamental principles.
Abstract: The aim of this research was to develop different ophthalmic gels of gatifloxacin using mucoadhesive polymers. To improve intraocular delivery of topically applied drugs such as gatifloxacin, gel formulations were prepared since solutions have a shorter ocular residence time because of tear turnover. A 3(2) factorial design was used to investigate the combined effect of two independent formulation variables in the preparation of the gels. Nine batches were prepared as per experimental design and evaluated for gelation temperature, gel strength, bioadhesion, viscosity, permeation, and antimicrobial efficacy. A surface plot was also created to graphically represent the effect of the independent variables on the evaluation parameters. Drug polymer compatibility was evaluated by differential scanning calorimetry and Fourier transform infrared spectroscopy. The prepared gels were observed to have a satisfactory gelation temperature, gel strength, and bioadhesion. Rheological study of the formulations indicated that gels exhibited pseudoplastic rheology. A modified device was used to evaluate drug permeation through a sheep's corneal membrane. In vitro permeation studies showed that a Peppas model was the best-fit model. Antimicrobial studies also indicated efficacy comparable to that of a marketed formulation. This systematic approach to formulation design should help in investigating the effect of variables in formulation processing.
Abstract: The aim of the present work was to prepare and evaluate sustained release liquisolid compact formulations of tramadol hydrochloride. The dissolution profile of the prepared compacts was also compared to that of a marketed preparation. Liquisolid sustained release formulations were prepared by using HPMC K4M as a sustained release agent. Precompression studies of characteristics such as flow properties were also carried out. Liquisolid compacts were evaluated by hardness, friability, and in vitro dissolution studies. Comparison of dissolution profiles was carried out by using a modelindependent, model-dependent, and statistical approach. The prepared liquisolid compacts are new dosage forms with better sustained release behavior compared to a marketed sustained formulation. The dissolution profile followed the Peppas model as "best fit" model. Two-way ANOVA results revealed a significant difference in dissolution profiles. This systematic approach to producing a formulation was found to help with analyzing the sustained release of tramadol hydrochloride. The use and evaluation of model-dependent methods is more complicated. These methods provide an acceptable model approach that indicates the true relationship between percent drug release and time variables, including statistical assumptions.
Abstract: The purpose of the present research was to study the effects of Ceolus KG-802 on the dissolution behavior of fenofibrate liquisolid tablets. The fenofibrate liquisolid tablets were formulated using the mathematical model described by Spireas et al. In the present research, Ceolus KG-802, a different form of microcrystalline cellulose (PH 102 grade), was used as a carrier material. The developed formulations were subjected to preformulation studies such as differential scanning calorimetry, X-ray powder diffraction, and determination of flow properties. The liquisolid tablets prepared were studied for their in vitro dissolution and compared to liquisolid tablets prepared using Avicel PH 102. The in vitro dissolution profiles of liquisolid tablets prepared using Ceolus KG-802 indicated slower dissolution than those of liquisolid tablets prepared using Avicel PH 102, which was a subject of earlier studies. This might be due to the particle size, shape, and characteristic properties of Ceolus KG-802.
Abstract: The purpose of the present study was to develop ophthalmic gel formulations of fluconazole. Intraocular delivery of topically applied drugs such as fluconazole is hampered by elimination of the solution due to tear turnover, so an in situ gelling thermoreversible mucoadhesive gel was formulated. Thermoreversible mucoadhesive gels were prepared using the cold method along with poloxamer 407 and different mucoadhesive polymers such as hydroxy ethyl cellulose (HEC), hydroxy propyl methyl cellulose (HPMC) K4M, and polyvinyl pyrrolidone (PVP) K30. Gels were evaluated for physical parameters like appearance, gelation temperature, pH, spreadability, drug content, gel strength, bioadhesion, and in vitro permeation. A modified device (modified K-C diffusion cell with a sheep's eye corneal membrane as a diffusion membrane) was used for evaluation of drug permeation through a sheep's corneal membrane. The formulated gels were transparent, uniform in consistency, and had spreadability with a pH range of 6.8 to 7.3. Satisfactory bioadhesion on the sheep's corneal surface and good gel strength were also observed. Diffusion studies have shown that a matrix is the best-fit model. As the concentration of mucoadhesive agent increases, the rate of permeation decreases. The order of drug permeation through the membrane was HEC > PVP K30 > HPMC K4M. This study found that a thermoreversible polymer and mucoadhesive polymers can be effectively used to prolong residence time.
Abstract: Sumatriptan succinate is an agonist for a vascular 5-hydroxytryptamine (5-HT)1 receptor subtype (probably a member of the 5-HT1D family). It does not have significant affinity for the remaining 5-HT receptors. It does not have affinity for alpha1, alpha2 or beta-adrenergic, dopamine1, dopamine2, muscarinic or benzodiazepine receptors. The objective of the study was to evaluate the in vitro transnasal absorption of sumatriptan succinate through sheep nasal mucosa and to determine its in vitro permeation behavior from various formulations containing penetration enhancers. In this study four different thermoreversible gel formulations designed for nasal delivery of sumatriptan succinate were formulated. The formulations were prepared by using a poly(oxythylene) poly(oxypropylene) block copolymer (Pluronic F 127) based gel along with different permeation enhancers and a pluronic lecithin organogel base. The effect of different concentrations of sodium glycocolate, EDTA and transcutol on in vitro nasal diffusion of sumatriptan succinate was studied. The best permeation profile was obtained with a formulation containing transcutol at a concentration of 0.005% w/w. Pluronic lecithin organogel showed good gelling properties at a concentration in the 20% range.
Abstract: The purpose of this research was to study mucoadhesive microspheres of tramadol hydrochloride compressed into tablet along with a loading dose. Microspheres containing tramadol hydrochloride were prepared by employing sodium alginate in combination with a mucoadhesive polymer, i.e., Carbopol 971P. An orifice-ionic gelation method was used to prepare the microspheres. A 3(2) factorial design was used to investigate the combined effect of two independent formulation variables in the preparation of microspheres. The concentration of sodium alginate (X(1)) and carbopol 971P (X(2)) were selected as independent variables. Nine batches were used in the experimental design and evaluated for swelling index, mucoadhesion, and drug entrapment efficiency. A surface plot is presented to graphically represent the effect of the independent variables on the evaluation parameters. The best batch exhibited drug entrapment efficiency of 70.12%, swelling index of 2.3 and mucoadhesion of 95.42%. Microspheres showing maximum drug entrapment were compressed with the loading dose and subjected to in vitro dissolution studies. Drug release from tablets was found to follow a matrix model. Initial burst release from these tablets indicated the release of the loading dose and then a sustained effect over the time. This modified approach to formulation of tablets was found to be effective in sustaining drug release.
