A variable presentation of Joubert syndrome: Case report and a brief review.

Joubert syndrome is a rare neurological manifestation usually present in late infancy or early childhood with characteristic episodes of abnormal breathing pattern along with the neurological and other systemic involvement.We report a case of confirmed Joubert syndrome present in the immediate neonatal period with isolated spells of oxygen desaturations not accompanied by the classically described breathing pattern and absent neurological symptoms causing delay in the diagnosis. Isolated oxygen desaturation episodes could be a presenting manifestation of Joubert syndrome in a neonatal period.

Development and evaluation of nifedipine controlled release tablets prepared using mucoadhesive swellable polymer.

Nifedipine is embedded in Gelcarin GP-379 to develop a prolonged release matrix. The effect of polymers levels (15, 20, 30 and 50% w/w), diluent type (lactose Fast Flo, DiTab, and Avicel PH-101), and drug levels (13, 20 and 30% w/w) on in vitro release rate of the drug were investigated. The formulation containing 13% nifedipine, 20% Gelcarin GP-379, and lactose Fast Flo controlled the dissolution rate of nifedipine and released approximately 51% drug at 8 h of testing dissolution. The use of different types of diluents, different drug levels, and different rotational speeds during dissolution testing did affect the drug release rate from the swellable matrices. The dissolution data were analyzed according to Higuchi model, zero order, first order, and Peppas kinetic model. Drug release was found to follow the anomalous diffusion model for swellable matrix.

Modified drug release of poloxamer matrix by including water-soluble and water-insoluble polymer.

BACKGROUND: The ability of poloxamer 407 to control drug release was investigated along with the effect of incorporation of a second polymer with poloxamer on dissolution behavior. METHODS: Tablets made of 30% w/w/ theophylline and 15%, 25%, 50%, or 69% poloxamer were prepared. Additionally, tablets containing mixture of poloxamer with carbomer or hypromellose in a 1:1 ratio and at different total levels (15%, 30%, and 50%) were also tested. RESULTS: Data show that as the level of poloxamer increased, drug release decreased. Formulations containing poloxamer: hypromellose 1:1 at 50% level and formulations containing poloxamer: carbomer 1:1 at 30% level produced controlled release matrices over 24 hours of testing dissolution. The mechanism of drug release follows anomalous relaxation non-Fickian diffusion model. CONCLUSIONS: These results suggest that the combination of poloxamer 407 with hypromellose or carbomer is feasible and has potential to offer the formulator control over drug release.

In vitro evaluation of theophylline matrices using xyloglucan.

Xyloglucan is a water soluble polysaccharide extracted from the beans of Tamarindus Indica. Very few publications are found related to its use for preparing oral sustained release swellable matrix. The purpose of this investigation was to prepare sustained release matrices using Xyloglucan and investigate the effects of polymer level, diluents type, pH and ionic strength of the dissolution medium, basket rotational speed, and swelling isotherms on drug release. Tablet formulations containing 50% theophylline as a drug model, Xyloglucan cold water soluble (20%, 30 and 40%) and different diluents (Avicel PH-101, lactose and dibasic calcium phosphate) were prepared. The formulation containing 30% Xyloglucan water soluble and Avicel was selected as best formulation because it gives controlled release profile and tested for swelling isotherms, drug release in different dissolution media, and different basket rotational speed. Percent drug release from formulations containing 50% theophylline, 30% Xyloglucan water soluble, and Avicel PH-101 was 34.2% at 6 hours, 35.6% with lactose, and 30.9% with Emcompress. ANOVA two-way analysis showed a change in drug release rate when polymer percent was increased at the 5% significance level. Different diluents, different dissolution media, and different basket rotational speeds did not significantly change the drug release. The mechanism of drug release appears to follow anomalous relaxation for swellable matrix.

Formulation and characterization of nystatin gel

The main objective of this research is to develop and characterize a series of carbopol 934 (CP) hydroxypropyl methylcellulose (HPMC) and a combination of carbopol-HPMC as a gel base for topical delivery of nystatin. The drug level was held constant at 1.72% w/w and the level of propylene glycol which is used as a co-solvent and penetration enhancer was also kept constant at 2% w/w. The total level of the polymer was held constant at 1.5% w/w as a single polymer or combination of two polymers. The polymers combination selected were: carbopol 934 to HPMC at a ratio of 0:1, 1:0, 1:2, 2:1 and 1:1. The batch size was 500 g and triethanolamine was used to adjust the pH of the gel. The rheological study showed that formulation containing combination of 2 carbopol and 1 HPMC ratio gave the highest viscosity, and exhibited an apparent pseudoplastic thixotropic behavior. The diffusion study indicated that gel formulation containing carbopol-HPMC at a ratio of 2:1 gave the highest percent drug diffusion compared to formulation containing low carbopol to HPMC ratio, carbopol alone or HPMC alone. Both in-vitro release and rheological study indicated that carbopol-HPMC had the best gel strength, physical properties and ability to diffuse the drug than carbopol or HPMC alone. The results obtained in this study demonstrated that the combination of carbopol and hydroxypropyl methylcellulose can be used as a gel vehicle for nystatin topical application.

Use of near-infrared for quantitative measurement of viscosity and concentration of active ingredient in pharmaceutical gel.

Near infrared (NIR) spectroscopy is gaining worldwide interest as an analytical tool for quality control of raw materials, intermediate products, and final dosage forms. This technique can be used without sample preparation, therefore, avoiding the need for reagents and solvents. Quantitative NIR analyses involve calibration by sophisticated mathematical techniques that have been used extensively since the advent of microcomputing and chemometrics. The main objective of this investigation was to use transmission near-Infrared spectroscopy to measure the potency of an active ingredient in a topical gel preparation. A second objective was to evaluate the effect of gel viscosity on the NIR reflectance spectra. Four gel formulations with different ibuprofen concentrations were used for quantitative determination of the active ingredient, and five gel formulations with different viscosity values were used for the evaluation of the effect of viscosity change on the near-infrared reflectance spectra. The laboratory ibuprofen quantitative determination was compared to near-infrared transmission data using linear, quadratic, cubic and partial least square techniques to determine the relationship between ultraviolet (UV) determination and near-infrared spectra. For viscosity, the laboratory data were compared to near-infrared diffuse reflectance data using the same techniques used to determine the relationship between Brookfield viscometer determination and near-infrared spectra. The results demonstrated that an increase in ibuprofen concentration and viscosity produced an increase in near-infrared absorbance. Series of model equations were developed from the calibration of laboratory vs. the near-infrared data for each formulation. The near-infrared spectroscopy method is an alternative method that does not require sample pretreatment for quantitative measurement of active ingredient and viscosity of pharmaceutical gel.

Effect of hydrodynamic environment on tablet dissolution using flow-through dissolution apparatus

The main objective of this research is to investigate the principles underlying the dissolution process, study the phenomena of drug release in laminar flow, and better understand the effect of hydrodynamic condition on drug dissolution, in order to predict drug dissolution from a solid dosage form. Two drug models were selected, theophylline (Class I) and naproxen (Class II), and were formulated into conventional tablets containing 105 mg theophylline or 300 mg naproxen using wet granulation method. Additionally theophylline (105 mg) and naproxen (300 mg) matrices containing 30hydroxypropylmethylcellulose (HPMC) polymer were prepared by direct compression and tested for dissolution using both USP II and IV dissolution apparatus. Tablets were tested for dissolution (USP IV) using different cell diameter, flow rate, and different position of the tablet inside the cell. In general, the drug dissolution at a given time is a direct function of the flow rate, increasing the flow rate increases drug release. The use of a small cell resulted in faster drug dissolution and higher Reynold's Number than using a large cell. Tablet position in the cell, also has an effect on drug dissolution, inserting the tablet in a horizontal position inside the cell gave faster dissolution than a vertical position. The hydrodynamic conditions did not affect the drug dissolution from HPMC controlled release tablets indicating that the drug dissolution is controlled by the matrix. An equation to predict drug dissolution from conventional tablets was established: Sh=-21.36+10.58Re(1/2) where R2=0.98. This study demonstrated that hydrodynamic conditions, and type of dissolution testing apparatus used have an effect on dissolution rate, mass transfer rate, and film thickness underlying dissolution process.

Effect of hydrodynamic environment on tablets dissolution rate.

The main objective of this research was to develop an experimental method to apply well-defined flow fields to solid dosage forms, to study the rate process underlying tablet dissolution, and to better understand the role of external hydrodynamic condition on mass transfer rate and film thickness during dissolution. Two drugs models, Theophylline (class 1) and Naproxen (class 2), were selected and formulated into conventional tablets containing 105 mg Theophylline or 300 mg Naproxen using the wet granulation method. Tablets were tested for dissolution using both the basket and paddle methods at different rotational speed of 25, 50, 75, and 100 rpm. In general, the paddle method gave higher dissolution rates than the basket method and as the velocity of rotation was increased, drug release was also increased. Six different paddles and a tablet holder were designed and used to test dissolution rate. The rate of dissolution was dependent on the tablet surface area exposed to the dissolution medium, and on the shape, diameter, and area of the paddles used. Theophylline tablets showed increased mass transfer rate and decreased film thickness as basket rotation speed was increased. At 25 rpm, the mass transfer coefficient was 0.684 x 10(-4) cm/sec and film thickness was 12.003 x 10(-2) cm; at 100 rpm, the mass transfer coefficient was 3.884 x 10(-4) cm/sec and film thickness was 2.114 x 10(-2) cm. Paddle values tested at the same speed showed higher mass transfer coefficient and lower film thickness for Theophylline and Naproxen tablets. P values obtained by modification of the Stokes-Einstein equation showed that diffusion is the rate-limiting step to drug release and not mass transfer. This study demonstrated that hydrodynamic condition, type of dissolution testing used, and design of the paddles have an effect on dissolution rate, mass transfer rate, and the film thickness underlying the dissolution process.

Relationship between internal phase volume and emulsion stability: the cetyl alcohol/stearyl alcohol system.

The main objective of this study was to optimize the stability of cetyl alcohol/stearyl alcohol emulsions in terms of percentage of internal phase volume, emulsifier type and concentration, and amount of external phase (water). Creams (o/w emulsions) were prepared by phase inversion and physical properties as particle size of the internal phase, apparent viscosity, and sedimentation volume evaluated. Stability was performed at room temperature, 40 degrees C, 50 degrees C, and under stress conditions. High hydrophilic lipophilic balance (HLB) nonionic surfactants as tween 80, tween 20, Myrj 52, Brij 35, and low HLB span 60 were used as emulsifying agents. The percentage of internal phase components (cetyl alcohol and stearyl alcohol), percentage of emulsifying agents, and percentage of aqueous external phase were varied, and stability was investigated. As the level of emulsifier agent (tween 80 and span 60) increased from 3% to 15%, and the percent of the internal phase remained constant at 30%, the particle size of the internal phase decreased and the cream became more stable. Formulations of the same composition, but prepared using Myrj 53 and tween 20 as emulsifiers, showed a larger particle size than formulations prepared using tween 80 and Brij 35. As the level of the internal phase volume increased and consequently the amount of water decreased, emulsion viscosity increased. The best formulation containing 30% internal phase (50% cetyl alcohol, 35% stearyl alcohol), 15% emulsifying agents (tween 80/span 60 ratio of 3:1), and 70% water was selected, and effects of process temperature and cooling rate on emulsion stability investigated. This formulation was further investigated in terms of stability of a 1% hydrocortisone addition by varying the percentage (30%, 35%, 40%, and 45%) of internal phase and percentage of water (70%, 65%, 60%, and 55%). The best formulation contained 45% internal phase (22.5 g cetyl alcohol, 15.75 g stearyl alcohol, 15% emulsifying agent, which is equivalent to 5 g tween 80 and 1.7 g span 60), and 55% w/w water, was manufactured under different manufacturing processes. Emulsions prepared by homogenization at the beginning of the process of emulsification were stable with small internal phase particle diameter. This study demonstrates that at every cetyl alcohol/stearyl alcohol ratio there is a phase volume/emulsifier HLB ratio, which results in optimum stability.

Evaluation of bioadhesive glipizide spheres and compacts from spheres prepared by extruder/marumerizer technique.

The objective of this study was to attempt to deliver glipizide from spheres and compacts containing the natural polymer Carrageenan (Gelcarin, GP 812) and prepared by extruder/marumerizer technique. A second objective was to evaluate the mucoadhesive strength of the bioadhesive spheres onto the mucus membrane of rabbit. The effects of polymer, drug level, and type of spheronizing material were evaluated. All sphere formulations were compacted into tablets using a rotary Manesty B-3B machine equipped with 12/32 flat face tooling. Results show drug release from spheres and compacts decreased as the level of Carrageenan was increased. However as the level of drug was increased drug release also increased. Spheres containing Avicel PH-101 gave higher drug release than spheres of the same composition but prepared with Avicel RC-581. In general, the drug release from tablets was higher than its corresponding spheres and drug release from spheres and tablets containing Carrageenan was higher than control spheres and tablets of the same composition but without Carrageenan. Tablet formulations compacted from spheres containing Avicel RC-581 gave higher release rate constants than tablet formulations of the same composition but prepared with Avicel PH-101. The bioadhesion study showed that mucoadhesion strength between spheres and mucus membrane of the rabbit depends on the levels of polymer, drug, and type of spheronizing material. Developed bioadhesive spheres and tablets increase the solubility of glipizide which may increase its bioavailability and also increased the adherence of the bioadhesive systems to the mucous membrane so that once daily dose can be administered.

Preliminary evaluation of glipizide spheres and compacts from spheres prepared by cross-linking technique.

The objective of this research was to use the natural polymer Carrageenan to obtain controlled release spheres loaded with glipizide using the cross-linking technique. The effect of polymer level and drug load were investigated. The drug was dispersed in Carrageenan solution and the dispersion was dropped by a device containing 3 disposable syringes into cross-linking solution containing 3% calcium chloride. After 15 minutes residence time, the spheres were collected by decantation and dried in hot air oven at 38 degrees C +/- 2 degrees C for 24 hours. The dried spheres were successfully compacted into tablets using rotary Manesty B-3B machine equipped with 12/32 inches round flat face punches, target tablet weight was 400 mg +/- 5%. As the polymer level was increased in the sphere formulation, the drug release rate was increased. However, as the drug level was increased in the sphere formulation, the release rate was decreased. This trend was also true for tablets compacted from spheres. The scanning electron microscope photographs supported the dissolution data. More cracks and rough surface were observed in tablets compacted from spheres containing high polymer level and low drug level.

Protein binding of glipizide using equilibrium dialysis technique: effects of hydrogen ion concentration, drug concentration and ionic strength.

The objective of this research was to investigate the effects of hydrogen ion concentration, drug concentration and ionic strength on the binding affinity of glipizide to albumin protein. Different buffer solutions of different pH values (pH 6.7, 7.5 and 8.5), different drug concentrations (2.45 mg, 4.82 mg and 9.42 mg), and phosphate buffer solutions pH 7.5 of different ionic strength (0.1, 0.4 and 1.0) were prepared. The effects of pH, drug concentration and ionic strength on the amount of glipizide bounded to 0.25 g bovine albumin was investigated. As the pH of the solution was increased from pH 6.4 to pH 8.5, milligrams drug bounded to gram protein (r value) decreased from 8.2 mg to 3.84 mg/g protein. Also as the ionic strength of the solution was increased from 0.1 to 1.0, the r value decreased from 10.76 mg to 3.96 mg/g protein. However, the r value did not change significantly with increasing of drug from 2.45 mg to 9.42 mg/25 ml. The r value was 7.36 mg/g protein when concentration of the drug was 2.45 mg/25 ml and 7.4 mg/g protein when the concentration of the drug was 9.42 mg/25 ml. This study demonstrated that factors such as high pH and high ionic strength can alter drug-protein binding and consequently increase free drug in plasma and increase bioavailability of slightly water insoluble drug such as antidiabetic drugs.

Drug release from Carbomer 934 matrices.

The main objective of this investigation was to describe the mechanism of drug release from Carbomer 934 hydrogel matrices and to evaluate the effect of polymer level, diluent type, and matrix restriction using customized device (that permits only one surface of the tablet to be exposed to the dissolution medium) on theophylline release from Carbomer matrices. Formulations containing theophylline (10%), Carbomer (10%, 30, 50%), direct compressible diluent (lactose fast flo, Avicel PH-101, Emcompress) and magnesium stearate (0.75%) were compressed at a target tablet weight of 450 mg and target hardness of 7-9 Kp. USP Apparatus 1, was used to test the drug release and Korsmeyer equation was used to describe the mechanism of drug release from Carbomer matrices. Results show that the release profile and release mechanism from Carbomer matrices were influenced by Carbomer level, diluent type, and matrix restriction. In general the release mechanism was anomalous (non-Fickian) except for 10% and 30% Carbomer level and in Avicel PH-101 matrices, where, the release mechanism appears to follow super case II where, the n exponent has value greater than 0.89. All formulations selected appear to follow zero order release only up to 120 minutes. Restriction of tablet surface resulted in a shift toward Fickian release. This study demonstrated that it is possible to modify the drug release mechanism and rate, by changing polymer level, diluent type, and imposing physical restriction on the surface of the matrix.

Kinetic release of theophylline from hydrophilic swellable matrices.

The objective of this research was to evaluate the effect of hydroxypropylmethylcellulose (HPMC; Methocel K4M Premium) level and type of excipient on theophylline release and to attempt to predict the drug release from hydrophilic swellable matrices. Formulations containing theophylline anhydrous (10% w/w), Methocel K4M Premium (10%, 30%, and 40% w/w), different diluents (Lactose Fast Flo, Avicel PH-101, and Emcompress), and magnesium stearate (0.75% w/w) were prepared by direct compression at a target weight of 450 mg +/- 5% and target hardness of 7 kp to 10 kp. It was found that, as the percentage of polymer in all formulations increased from 10% to 30% or 40%, the drug release decreased. However, there was no significant difference in drug release between formulations containing 30% polymer and formulations containing 40% polymer. At low levels of polymer, the drug release is controlled by the type of diluent used. Avicel PH-101 formulation gave the highest release, while its corresponding Emcompress formulation gave the lowest release. Formulations containing 30% or 40% polymer gave the same release profiles irrespective of the type of diluent used. In all cases, replacement of a portion of Methocel K4M Premium with any diluent resulted in increase of theophylline release. In addition, this investigation demonstrated that the drug release from hydrophilic swellable matrices can be predicted using only a minimum number of experiments.

Compressional characterization of two dextrose-based directly compressible excipients using an instrumented tablet press.

The main objective of this work was to evaluate the compaction behavior and record the work and the force involved in the compaction of blends and granules of two dextrose-based directly compressed excipients using a single-punch instrumented tablet press. The second objective was to identify the predominant form of deformation for the two different directly compressible excipients. Anhydrous theophylline (10% w/w) was used as a drug model, Emdex and/or Maltrin M 510 (89.5% w/w) were used as diluent, and magnesium stearate (0.5% w/w) was used as lubricant. All formulations were compressed at four different compressional forces and at a target tablet weight of 450 mg +/- 5%. Results show that compacts prepared from Emdex using the direct compression method produced the lowest elastic work and die wall friction, and the best degree of lubrication. Wet granulation for Maltrin M 510 decreased elastic work, frictional work, and ejection force, and enhanced both net work and degree of lubrication. In general, wet granulation for both Emdex and Maltrin M 510 decreased the crushing strength of the tablets and enhanced the degree of lubrication, compared to direct compression formulations. All formulations showed similar shape pattern for plastic deformation, suggesting that the predominant mechanism of deformation is plastic deformation type a Heckel plots.

Evaluation of two dextrose-based directly compressible excipients.

The objectives of this research were to evaluate the physical properties and compaction behavior of two dextrose-based directly compressed excipients. Anhydrous theophylline (10% w/w) was used as a drug model, Emdex and or Maltrin M510 (89.5% w/w) were used as diluent, and magnesium stearate (0.5% w/w) was used as lubricant. Direct compression and wet granulation methods were used for preparing the compacts. In general, the wet granulation method reduced the density of the mixture and consequently its flow rate compared to the mixture prepared only by solid-solid mixing. All formulations were compressed at four different compressional forces and at a target weight of 450 mg +/- 5%. Tablets obtained were different in physical properties and mechanical strength based on type of excipient used and methods of tablet preparation (direct compression versus wet granulation). Compacts prepared from Maltrin M510 had a longer disintegration time and slower drug release than compacts of the same composition but prepared with Emdex. Disintegration time and drug dissolution from tablets containing Maltrin M510 as diluent and prepared by wet granulation appeared to be controlled by a "gel" layer formation around the tablets and not by the tablets porosity. This study demonstrates that full characterization of excipients is needed because a different manufacturing process for the same excipients may produce differences in the pharmaceutical products.

Mechanisms of chlorpheniramine maleate release from hydrophilic swellable polymer systems.

The main objective of this work is to attempt to understand better the mechanism of release of highly water soluble drugs from a swellable polymer and to quantify the amount of drug released. Tablets containing 10% w/w drug, hydroxypropylmethylcellulose E4M (10% w/w, 20% w/w and 30% w/w), 1% w/w magnesium stearate and quantity sufficient to 100% w/w with Lactose Fast Flo as diluent were prepared using the direct compression method. The amount of drug released due to Fickian diffusion and non-Fickian diffusion (polymer relaxation) was quantified at different time intervals. In order to determine if the drug release was Fickian diffusion or non-Fickian diffusion, the exponent n obtained from the equation: Mt/M yen = Ktn was calculated. It was found to be above 0.5 for restricted and unrestricted systems indicating non-Fickian diffusion. Also, the approximate contribution of Fickian diffusion and polymer relaxation to the non-Fickian anomalous release process was calculated. The data obtained from one tablet surface and all surfaces exposed to the dissolution medium demonstrated that Fickian diffusion predominated for the first hour. After one hour of testing dissolution, the relaxational mechanism predominated. The percent drug release from restricted matrices at 6 hours of dissolution testing was 77.9% by polymer relaxation and 27.9% by Fickian diffusion.

In-vitro evaluation of sustained release ibuprofen microspheres.

Microspheres for oral use have been employed to target and to sustain the release of the drug. The objective of this study was to use the melt dispersion technique and aqueous vehicle to entrap ibuprofen into wax carrier (carnauba wax) with the aid of surfactant (Pluronic L-62). The effects of different levels of Pluronic L-62, stirring speed, and ibuprofen levels, as well as the in-vitro release rate of ibuprofen were evaluated. The in-vitro dissolution of ibuprofen in phosphate buffer pH 7.2 showed that microspheres prepared with low amount of drug (1.5 g) released 58.1% of ibuprofen after 6 hours, while microspheres prepared with high amount of drug (6.0 g) released only 38.9% of ibuprofen. Microsphere formulations prepared by using aqueous vehicle were spherical and of smooth surface. In general the melt dispersion technique was a successful method for preparing sustained release ibuprofen microspheres.

In-vitro evaluation of sustained release ibuprofen microspheres

Microspheres for oral use have been employed to target and to sustain the release of the drug. The objective of this study was to use the melt dispersion technique and aqueous vehicle to entrap ibuprofen into wax carrier (carnauba wax) with the aid of surfactant (Pluronic L-62). The effects of different levels of Pluronic L-62, stirring speed, and ibuprofen levels, as well as the in-vitro release rate of ibuprofen were evaluated. The in-vitro dissolution of ibuprofen in phosphate buffer pH 7.2 showed that microspheres prepared with low amount of drug (1.5 g) released 58.1 percent of ibuprofen after 6 hours, while microspheres prepared with high amount of drug (6.0 g) released only 38.9 percent of ibuprofen. Microsphere formulations prepared by using aqueous vehicle were spherical and of smooth surface. In general the melt dispersion technique was a successful method for preparing sustained release ibuprofen microspheres

Modified release matrix prepared by compaction of spheres containing waxy material.

In this study, chlorpheniramine maleate spheres were prepared by the extruder/marumerizer. A new waxy material, Gelucire 50/02 at three levels (10%, 30% and 50%) was added and Avicel PH-101 was used as spheronizing material. The drug was incorporated into the waxy material by two methods. The first was the direct method, in which the drug (10%), wax and Avicel PH-101 were mixed together. The second was the fusion method, in which the drug was dispersed in the melted wax and the solidified mass was milled and mixed with Avicel PH-101. The data obtained indicated that simple addition of waxy material into chlorpheniramine maleate-Avicel PH-101 spheres interrupted matrix formation and increased drug release. Also in this study, a multiparticulate delivery system was prepared successfully by compaction of spheres into tablets. Tablets compacted from spheres prepared by fusion method gave less drug release than those compacted from spheres of the same composition but prepared with direct method. As the level of wax was increased in tablet formulation, drug release was decreased.