Dissolution of Directly Compressed Thiamine Hydrochloride Tablets

Abstract

Directly compressed thiamine hydrochloride tablets with varying concentrations of different vehicles as well as their binary blends, were prepared for this investigation. The results showed that, formulated tablets with avicel anhydrous lactose and celutab completely dissolved within short times. First order mechanism was reported for the tablets prepared with single vehicles. The dissolution rate constant “K”, was a function of disintegration constant “D” of the tablets by the relation In K = a + n In D. In addition to that, it is proved that, “K” of produced tablets of short disintegration times was a function of the contributed vehicle concentration “C” by the relation, I/K = A exp. + NC.

On the other hand, (T 50%) of thiamine hydrochloride in a given batch was a function of its disintegration time.     

Degradation Kinetics of Thiamine Hydrochloride in Directly Compressed Tablets I: Effect of Ageing Under Varying Temperature and Relative Humidity Conditions

Abstract

The degrzadation kinetics of thiamine hydrochloride in tablets directly compressed with either single or binary vehicles was studied. The presult shows that, tabletted vitamin stored at varying temperature conditions degraded by first order mechanism. The magnitude of the rate constant K, was dependent on the type and concentration of the vehicle used. The decomposition of vitamin B₁ at varying temperatures was amenable to Arrhenius treatment. The degradation pattern of the vitamin in Avicel or binary blend of Avicel with another vehicle, stored at varying relative humidity conditions deviated from a first order mechanism. There was indication that equilibrium phenomenon is involved in the degradation of the vitamin contained in these vehicles. A log-linear relationship was seen to exist between K, and moisture content of the tablet.     

Preparation and Evaluation of Directly Compressed Medazepam Hydrochloride Tablets

Medazepam, the well known benzodiazepine derivative used as a transquillizer and in alcohol withdrawal, was prepared in directly compressed tablets. The directly compressible vehicles which were used. singly or in binary blends 1:1, were Avicel, Lactose, STA-Rx 1500 Emcompress and the recently introduced vehicle compactrol. It was found that Avicel and Emcompress represent the most suitable single vehicles used for the preparation of Medazepam hydrochloride tablets. In case of binary blends it was found that the best quality batches were prepared using Avicel Emcompress blend 1:1. Physical characteristics including uniformity of weight, thickness, hardness, friability were investigated for the prepared batches. The effect of directly compressible vehicle variation on the uniformity of drug content and the dissolution rates of Medazepam hydrochloride tablets was also studied.     

Soft Gelatin Capsules Iii: An Accelerated Method for Evaluating the Dissolution Stability of Various Gel Formulations

A rapid method has been developed for the evaluation of the dissolution stability of various preformulation gels. Freshly prepared gel samples, after proper drying, were stored over a drying agent at above room temperatures. Periodically the dissolution of a stability sample in % dissolved for a given time was determined spectrophotometrically. In this manner, various preformulation gels could be evaluated in a relatively short time by changes in their dissolution rates from a slope values versus time plot for a given storage condition. Other applications of the method were in screening various plasticizers and additives for their solubility enhancing or protective properties.     

Soft Gelatin Capsules Iii: An Accelerated Method for Evaluating the Dissolution Stability of Various Gel Formulations

Abstract

A rapid method has been developed for the evaluation of the dissolution stability of various preformulation gels. Freshly prepared gel samples, after proper drying, were stored over a drying agent at above room temperatures. Periodically the dissolution of a stability sample in % dissolved for a given time was determined spectrophotometrically. In this manner, various preformulation gels could be evaluated in a relatively short time by changes in their dissolution rates from a slope values versus time plot for a given storage condition. Other applications of the method were in screening various plasticizers and additives for their solubility enhancing or protective properties.     

Optimization of Slow-Release Tablet Formulations: Containing Montmorillonite I. Properties of Tablets

Slow-release tablets containing 20%. sodium sul fathiazole and 30%. magnesium aluminum silicate were prepared by direct compression techniques. Dissolution studies indicated that tablet hardness exerted a negligible influence on drug release from the tablets. During the dissolution process the clay slowly swelled to form a gelatinous hydrated layer around the tablet matrix. At faster stirring speeds, friction between the dissolution basket and the tablet rapidly removed the hydrated boundary region and resulted in a more rapid dissolution rate of the sulfonamide. Faster rates of dissolution were seen in deionized water than in dilute acid since the clay hydrated more readily at the higher pit.     

Directly Compressed Mini Matrix Tablets Containing Ibuprofen: Preparation and Evaluation of Sustained Release

ABSTRACT

Directly compressed mini tablets were produced containing either hydroxypropylmethylcellulose (HPMC) or ethylcellulose (EC) as release controlling agent. The dynamics of water uptake and erosion degree of polymer were investigated. By changing the polymer concentration, the ibuprofen release was modified. In identical quantities, EC produced a greater sustaining release effect than HPMC. Different grades of viscosity of HPMC did not modify ibuprofen release. For EC formulations, the contribution of diffusion was predominant in the ibuprofen release process. For HPMC preparations, the drug release approached zero-order during a period of 8 h. For comparative purposes, tablets with 10 mm diameter were produced.     

Evaluation of Mujol as a Direct Compression Excipient in Oxytetracycline Hydrochloride Tablet Formulations

Abstract

The physical properties of oxytetracyc1ine hydrochloride tablets compressed with Musol, a new autocompressib1e vehicle obtained by chemical modification of an edible seed polysaccharide were studied, Avice1 PH 101, Fast-f1o lactose and Emcompress were used as basis for comparison.

With the exception of those tablets containing Emcompress, good disintegration and dissolution profiles were obtained in all the batches formulated. The dissolution characteristics of the tablets did not change significantly after storage in the dark at 30°C for 96 weeks.     

A Stability Study of Clindamycin Hydrochloride and Phosphate Salts in Topical Formulations

Abstract

The stability of clindamycin hydrochloride and clindamycin phosphate was studied in topical liquid formulations prepared with the following solvents: solvent A (70% isopropanol, 10% propylene plycol and 20% water), solvent B (48% isopropanol, polyoxyethelene ethers, acetone, salicylic acid and allantoin), solvent C (40% alcohol, acetone, polysorbate 20, fragrance and water) and “standard” (50% isopropyl alcohol, propylene glycol and water) in glass and plastic containers at 25°, 40°, and 50°C.

It was found that, in general, better stability was obtained in glass containers than in plastic containers. At 25°C both the clindamycin hydrochloride and phosphate formulations in solvent B showed poorer stability than in the other solvents irrespective of the type of container, while formulations in solvent C showed the best stability. In addition, the effect of the pH on the stability of the formulations was determined, and it was clear that at pH values below 4 the stability of all formulations decreased.     

A Stability Study of Clindamycin Hydrochloride and Phosphate Salts in Topical Formulations

The stability of clindamycin hydrochloride and clindamycin phosphate was studied in topical liquid formulations prepared with the following solvents: solvent A (70% isopropanol, 10% propylene plycol and 20% water), solvent B (48% isopropanol, polyoxyethelene ethers, acetone, salicylic acid and allantoin), solvent C (40% alcohol, acetone, polysorbate 20, fragrance and water) and “standard” (50% isopropyl alcohol, propylene glycol and water) in glass and plastic containers at 25°, 40°, and 50°C.

It was found that, in general, better stability was obtained in glass containers than in plastic containers. At 25°C both the clindamycin hydrochloride and phosphate formulations in solvent B showed poorer stability than in the other solvents irrespective of the type of container, while formulations in solvent C showed the best stability. In addition, the effect of the pH on the stability of the formulations was determined, and it was clear that at pH values below 4 the stability of all formulations decreased.     

Color Stability: An Evaluation of Three Natural-Source Colorants as Components in Compressed Tablets

A modified colorimetric procedure was developed in order to measure changes in color in multiple-tablet beds rather than in individual tablets or other dosage forms. Fading, induced by exposure of the test product to an exaggerated illumination source, was assumed to be the nechanism for color change during the short-term studies. The color changes encountered during the long-term studies were attributed to the effects of chromatic distortion produced by storage conditions (time, temperature, humidity, and/or package).

This study encompassed an evaluation of three natural-source colorants included in the composition of compressed tablets. These colorants (carmine. cranberry, and raspberry) were selected as model components in the tablet formulas for the long-term storage studies because of their favorable photostability encountered during the short-term screening trials.     

Color Stability: An Evaluation of Three Natural-Source Colorants as Components in Compressed Tablets

Abstract

A modified colorimetric procedure was developed in order to measure changes in color in multiple-tablet beds rather than in individual tablets or other dosage forms. Fading, induced by exposure of the test product to an exaggerated illumination source, was assumed to be the nechanism for color change during the short-term studies. The color changes encountered during the long-term studies were attributed to the effects of chromatic distortion produced by storage conditions (time, temperature, humidity, and/or package).

This study encompassed an evaluation of three natural-source colorants included in the composition of compressed tablets. These colorants (carmine. cranberry, and raspberry) were selected as model components in the tablet formulas for the long-term storage studies because of their favorable photostability encountered during the short-term screening trials.     

Projection of Tentative Expiry Date from One-Point Accelerated Stability Testing II. Overage Consideration

A previous publication (1) analyzed a statement originated from the Food and Drug Administration (FDA) that a drug product which is stable for three months at 37-40° and 75% or higher relative humidity can be given a tentative expiry period of two years from the date of manufacture. Conditions which can be uesd to make a successful projection using such a proposal have been established. These conditions are applicable only to pharmaceutical systems which do not contain an overage. The theoretical discussion is extended in this communication to analyze the effect of the overage on the proposed projection of the expiry period. The analysis shows that the inclusion of the overage lowers the threshold activation energy needed to satisfy the FDA's proposal     

Projection of Tentative Expiry Date from One-Point Accelerated Stability Testing II. Overage Consideration

Abstract

A previous publication (1) analyzed a statement originated from the Food and Drug Administration (FDA) that a drug product which is stable for three months at 37–40° and 75% or higher relative humidity can be given a tentative expiry period of two years from the date of manufacture. Conditions which can be uesd to make a successful projection using such a proposal have been established. These conditions are applicable only to pharmaceutical systems which do not contain an overage. The theoretical discussion is extended in this communication to analyze the effect of the overage on the proposed projection of the expiry period. The analysis shows that the inclusion of the overage lowers the threshold activation energy needed to satisfy the FDA's proposal     

A Study of the Chemical and Physical Stability of Ascorbic Acid,Folic Acid,and Thiamine Hydrochloride Tablets Formulated with Emcompress Standard

Abstract

Tablets which were prepared from separate formulations of Emcompress Standard^R, a commercially available directly compressible granulation, with ascorbic acid, folic acid, and thiamine hydrochloride were subjected to accelerated aging conditions and studied for chemical stability and such physical parameters as hardness, friability, and disintegration time. Other physical factors which could affect the interpretation of the data, such as moisture content, particle size distribution, angle of repose, weight variation, and hardness were also studied using fresh samples.

Accelerated aging showed that the ascorbic acid formulation was chemically unstable; the tablets became soft, the frability increased markedly, and the disintegration time decreased. The folic acid formulation was chemically stable, but the tablets became soft, the friability increased, and disintegration time increased. The thiamine hydrochloride formulation was also chemically stable—the tablets became soft, the disintegration time decreased, and the friability increased.     

II. Segregation of Active Constituents from Tablet Formulations During Grinding: Significance to Pharmaceutical Analysis

The preparatory step in the analysis of active drugs in tablet dosage forms has generally consisted of the grinding or milling of a given number of the tablets into a fine powder. Certain drugs formulated as tablets have been shown to undergo physical separation from other tablet components as a result of grinding. This phenomenon accounts, at least in part, for the poor reproducibility found in duplicate assays for these drugs in tablet composites. This same phenomenon also explains discrepancies between the average of the individual tablet assay values of samples prepared by direct dissolution, and the assay value of the corresponding composites.

This paper illustrates this phenomenon using a problem dosage form and suggests methods of sample preparation that avoid segregation of ingredients. These methods include the direct dissolution of a representative number of individual tablets in a suitable solvent, the sieving and regrinding of the ground tablets, the grinding of a composite with a suitable organic solvent and the evaporation of the solvent, and the dissolution of the total composite tablet sample in a solvent.     

II. Segregation of Active Constituents from Tablet Formulations During Grinding: Significance to Pharmaceutical Analysis

Abstract

The preparatory step in the analysis of active drugs in tablet dosage forms has generally consisted of the grinding or milling of a given number of the tablets into a fine powder. Certain drugs formulated as tablets have been shown to undergo physical separation from other tablet components as a result of grinding. This phenomenon accounts, at least in part, for the poor reproducibility found in duplicate assays for these drugs in tablet composites. This same phenomenon also explains discrepancies between the average of the individual tablet assay values of samples prepared by direct dissolution, and the assay value of the corresponding composites.

This paper illustrates this phenomenon using a problem dosage form and suggests methods of sample preparation that avoid segregation of ingredients. These methods include the direct dissolution of a representative number of individual tablets in a suitable solvent, the sieving and regrinding of the ground tablets, the grinding of a composite with a suitable organic solvent and the evaporation of the solvent, and the dissolution of the total composite tablet sample in a solvent.     

Optimization of Direct Compression Tablet Formulations for Use in Tropical Countries

Abstract

With the aid of a combined mixture- and factorial- design, 2 standard tablet formulations were selected suitable for use in tropical countries. The formulations were based on native ingredients or ingredients that are available worldwide. The selection of the standard formulations was based on both the initial tablet properties of the formulations one day after preparation as well as the physical stability after storage under tropical conditions.

The selected formulations were evaluated by adding model drugs (diazepam, 2 mg per tablet or hydrochlorthiazide, 100 mg per tablet) and measuring tablet properties, not only one day after preparation, but also after storage under tropical conditions. Both selected tablet formulations were suitable standard formulations for tablets prepared by direct compression for use in tropical countries.     

Optimization of Direct Compression Tablet Formulations for Use in Tropical Countries

With the aid of a combined mixture- and factorial- design, 2 standard tablet formulations were selected suitable for use in tropical countries. The formulations were based on native ingredients or ingredients that are available worldwide. The selection of the standard formulations was based on both the initial tablet properties of the formulations one day after preparation as well as the physical stability after storage under tropical conditions.

The selected formulations were evaluated by adding model drugs (diazepam, 2 mg per tablet or hydrochlorthiazide, 100 mg per tablet) and measuring tablet properties, not only one day after preparation, but also after storage under tropical conditions. Both selected tablet formulations were suitable standard formulations for tablets prepared by direct compression for use in tropical countries.     

燃料电池质子交换膜的热稳定性和热降解动力学

采用热重分析(TGA)、Kissinger、Flynn-Wall-Ozawa、Friedman和Modified Coats-Redfem方法,在氮气气氛和升温速率分别为5℃/min、10℃/min、15℃/min和20℃/min条件下,研究了质子交换膜的热稳定性及热降解动力学。TG-DTG曲线显示该质子交换膜分解率达到5%时,最低热降解温度大于350℃,热分解过程经历两个阶段,第一和第二阶段热分解区间分别出现在340℃～440℃和405℃～600℃之间。采用不同方法的计算结果显示,第一阶段的平均表观活化能为155.8kJ/mol,第二阶段的平均表观活化能为177.1kJ/mol。