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At least 1,153 records · Page 64Linked to original sources

PubMed1978

Dissolution rates of hydrocortisone and prednisone utilizing sugar solid dispersion systems in tablet form.

The utilization of ternary sugar solid dispersion systems and the incorporation of these systems into tablet dosage forms were investigated. The dispersion systems were prepared by the fusion method using 50% sucrose-50% mannitol and 50% sorbitol-50% mannitol. Other systems investigated utilized sorbitol, mannitol, and polyethylene glycol 6000 for comparison. The drug component was hydrocortisone or prednisone. The results from a modified NF XIII dissolution rate determination revealed that the mannitol system had the fastest dissolution rate, followed by sorbitol-mannitol, sucrose-mannitol, sorbitol, and finally, polyethylene gylcol 6000. The corticosteroids were stable and did not decompose during preparation of the dispersion systems or direct compression of the tablets. A short-term stability study revealed that the tablets retained their fast dissolution rates and that the tablet characteristic tests, i.e., tablet hardness, remained unchanged. The use of sugar combinations overcame some difficulties previously reported with single sugar systems.

Chemistry, Pharmaceutical↗

PubMed1979

Effect of microcrystalline cellulose on liquid penetration in and disintegration of directly compressed tablets.

The penetration of isooctane and water into tablets of microcrystalline cellulose, dibasic calcium phosphate dihydrate, spray-crystallized maltose-dextrose, and blends of microcrystalline cellulose with one of the other excipients were studied. The isooctane penetrations occurred according to the Washburn equation and were not affected by the presence of 0.5 or 1.0% magnesium stearate. The inhibition of aqueous penetration into tablets resulting from hydrophobic magnesium stearate was less pronounced for vehicles like dibasic calcium phosphate, which exhibited extensive brittle fracture under compression. Microcrystalline cellulose tablets, both with and without magnesium stearate, exhibited extremely fast aqueous penetration even at low porosities, caused by breaking of the hydrogen bonds and subsequent widening of the pores. Ratios between water uptake and original pore volume up to 20 were obtained for microcrystalline cellulose tablets. This unique property was, however, suppressed by the presence of fast dissolving and highly soluble excipients like dextrose, resulting in an antagonistic disintegration behavior of tablets compressed at pressures over 10,000 N/cm2. Improved disintegration properties were obtained by blending microcrystalline cellulose with an insoluble vehicle such as dibasic calcium phosphate dihydrate.

Calcium Phosphates↗

PubMed1979

Tablet position and basket type effects in spin-filter dissolution device.

The effects of stirring and basket placement on tablet dissolution using the previously developed Shah spin-filter device were investigated. Visualization of flow and dissolution patterns was possible by testing nondisintegrating colored tablets. Dissolution experiments were conducted on nondisintegrating double-layered tablets containing salicylic acid as the dissolving layer and ethylcellulose as an inert nondissolving layer. Visual observations revealed that color was drawn more rapidly from the tablet face resting on the bottom of the basket. Dissolution data from multilayered tablets revealed that when the salicylic acid face was resting on the bottom of the basket, the dissolution was appreciably more rapid than when it was facing up in the basket. This phenomenon was found for several stirring speeds.

Diffusion↗

PubMed1980

Role of binders in moisture-induced hardness increase in compressed tablets and its effect on in vitro disintegration and dissolution.

The role of commonly used binders in the moisture-induced hardness increase in compressed tablets containing lactose as a major excipient was studied. Tablets compressed from granulations containing different binders at different moisture levels increased in hardness after overnight exposure to ambient room conditions. The results suggest that this hardness increase is related linearly to the amount of moisture loss from the tablets after compression. The magnitude of the hardness increase is related to the type and concentration of the binder used in wet granulation. The moisture-induced hardness increase in tablets prepared from granulations containing different binders had no effect on the tablet disintegration time and in vitro drug dissolution.

Chemical Phenomena↗

PubMed1982

Thiazides IV: Comparison of dissolution with bioavailability of chlorothiazide tablets.

Based on the initial dissolution rate profiles in water, a slow-dissolving, an intermediate-dissolving, and a fast-dissolving chlorothiazide 250-mg tablet were selected for the bioavailability and bioequivalence study. In addition, two marketed 500-mg chlorothiazide tablets were studied. The three 250-mg tablets were bioequivalent, as were the two 500-mg tablets. Therefore, the dissolution test conditions were modified to associate in vitro dissolution with in vivo performance of the product. Based on these results, it was concluded that a dissolution of 75% in 60 min by paddle method at 75 rpm in pH 7.4 phosphate buffer can be used as a quality assurance test for 250- and 500-mg chlorothiazide tablets.

Biological Availability↗

PubMed1983

Sustained release of theophylline from hydroxypropylcellulose tablets.

Compressed tablets were prepared from theophylline and hydroxypropylcellulose. Effects of the viscosity grades of the polymer, the mixing ratios of two polymers with different viscosity grades, and the polymer contents in the tablets on release patterns of theophylline were examined in vitro. Release rate was decreased with increasing viscosity designation and polymer contents in the tablets. In salivary level profiles of theophylline following oral administration of sustained-release tablets to five human volunteers, a low but sustained level was noted indicating sustained release of the drug from the tablets in vivo.

Administration, Oral↗

PubMed1988

Effect of binders on sulfamethoxazole tablets.

Five batches of sulfamethoxazole tablets were prepared using different binders [starch, acacia, ethyl cellulose sodium carboxymethylcellulose, and povidone (1-vinyl-2-pyrolidinone polymer, PVP)] with water in 3% (dry basis) concentration. Comparative data show that granules prepared with PVP have the best flow properties and minimum angle of repose, percentage fines, and compressibility, while granules of sodium carboxymethylcellulose could not be compressed into well-defined tablets. Tablets containing starch as a binder possess all the quality features. Tablets from acacia, however, give a poor dissolution profile. Ethyl cellulose has less effective granule formation, leading to poor quality tablets. Rank correlation with respect to solubility and absorption characteristics according to granulating agent in the formation is: starch greater than ethyl cellulose greater than PVP greater than acacia.

Absorption↗

PubMed1988

High-performance liquid chromatographic methods for the determination of ranitidine and related substances in raw materials and tablets.

High-performance liquid chromatographic methods have been developed for the determination of ranitidine and related compounds in drug raw material and tablets. The method has been shown to resolve at least nine related compounds from the drug. The sensitivity of the method to related compounds is better than 0.01%. Eight raw material samples and 11 tablet samples were examined for related compounds. Total impurities found ranged from 0.31 to 0.79% in raw materials and from 0.40 to 1.75% in tablets. Drug raw materials and tablets were assayed by HPLC; results for raw materials were between 98.2 and 101.1%, and those for tablets were between 96.1 and 102.2%, with a relative standard deviation for the assay of less than 1%. Raw material assay results were confirmed by nonaqueous titration.

Chemical Phenomena↗

PubMed1993

Effect of the mode of super disintegrant incorporation on dissolution in wet granulated tablets.

The effect of the mode of super disintegrant incorporation in wet granulated tablets was investigated with three super disintegrants: sodium starch glycolate, crospovidone, and croscarmellose sodium. The disintegrants were incorporated extragranularly or intragranularly or distributed equally between the two phases. Lactose, naproxen, or dibasic calcium phosphate was used as the principal tablet component to provide various degrees of solubility to the formulations. The formulations were dried to three different levels of moisture content. The results indicated that, for the formulations studied, extragranular incorporation resulted in faster dissolution than did equal distribution intragranularly and extragranularly, which in turn was superior to intragranular incorporation. Granulation moisture content was found to have a formulation-specific impact on tablet dissolution, with each main tablet component behaving in a different fashion. When all other factors were kept constant, there was a tendency for croscarmellose sodium to produce faster tablet dissolution than sodium starch glycolate or crospovidone. The super disintegrants tended to promote faster dissolution in a neutral pH medium than in an acidic medium.

Biological Availability↗

PubMed1993

Influence of the application site on bioadhesion and slow-release characteristics of a bioadhesive buccal slow-release tablet of miconazole.

The influence of the application site on bioadhesion and release characteristics of a bioadhesive buccal slow-release tablet of miconazole has been evaluated. The adhesion time and salivary miconazole levels were measured after application of the tablet to the gingiva, the cheek and the palate in 10 healthy volunteers. The longest adhesion time noted was for the gingiva (565 min), compared to the palate and cheek with adhesion times of 210 and 243 min, respectively. Tablets adherent to the palate showed the highest initial salivary drug levels, followed by those adherent to the cheek and gingiva, respectively. The clearance rate from the oral cavity was similar when the tablet was applied to the palate and the cheek, but it was markedly decreased when applied to the gingiva. It is concluded that the gingiva is the best site for application of a bioadhesive buccal system for local therapy. A study in 8 comatose intubated patients showed that the application site had to be adapted to the state of the patients treated, as salivary miconazole concentrations comparable to those observed with the gingival tablet in healthy volunteers, were obtained after application to the cheek.

Adhesiveness↗

PubMed1988

Pharmacokinetic and pharmacodynamic properties of a new controlled-release formulation of metoprolol: a comparison with conventional tablets.

The pharmacokinetic and pharmacodynamic properties of a new multiple-unit, controlled-release (CR) formulation of metoprolol (metoprolol succinate, 95 mg once daily), which has almost constant (zero-order) release properties over most of a 24-h dose interval, have been compared with those of conventional metoprolol tablets (metoprolol tartrate, 100 mg once daily and 50 mg twice daily), in 12 healthy male volunteers. The steady-state plasma concentrations of metoprolol after five days of treatment varied less throughout the day with the CR than with the conventional formulation. This was associated with a considerably lower peak plasma concentration and the achievement of a significantly higher plasma concentration at the end of the dose interval. Similarly, the effect on exercise-induced tachycardia was maintained at a relatively constant level throughout the day after treatment with the CR formulation. A significantly greater effect 24 h after administration was achieved with the CR formulation, when compared with once-daily dosing with metoprolol tablets, 100 mg. Twice-daily dosing with metoprolol tablets, 50 mg, produced a similar beta 1-blocking effect at the end of the dose interval to that observed with metoprolol CR. Although the steady-state plasma concentrations indicated significantly lower systemic availability for the CR formulation, compared with both regimens of metoprolol tablets, the total effect over the dose interval, expressed as the area under the efficacy curve (AUEC), was similar for the three treatments. The relationship between steady-state plasma concentrations and the pharmacodynamic efficacy at corresponding times, indicated that plasma concentrations were more effectively utilized after the administration of the CR formulation than after the conventional tablet regimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Effect of controlled-release metoprolol on blood pressure and exercise heart rate in hypertension: a comparison with conventional tablets.

In a double-blind study with parallel groups a new controlled-release (CR) formulation of metoprolol, 100 mg once daily, was compared with conventional metoprolol tablets, 100 mg once daily, in 27 patients with primary hypertension. Exercise tests on a bicycle ergometer were undertaken 24 h after intake of the last dose of the drug following a four-week placebo run-in period and after four weeks of active treatment. Heart rate, measured in the supine position and during exercise at the highest comparable workload, was reduced significantly more by metoprolol CR (p less than 0.05), thus indicating a higher degree of beta 1-blockade at the end of the dose interval with metoprolol CR. There was a greater reduction in supine systolic pressure (p less than 0.05) but not in supine diastolic pressure after metoprolol CR than after conventional tablets at 24 h. There was no significant difference between the two groups with respect to reduction in systolic blood pressure during exercise. The 24-h plasma concentrations of metoprolol CR and conventional tablets correlated with the effects on heart rate, but not with blood pressure. The tolerability of metoprolol CR was comparable with that of metoprolol administered as conventional tablets. In conclusion, there was significantly greater beta 1-blockade 24 h after the intake of drug after metoprolol CR compared with conventional tablets.

Adult↗

PubMed1988

Efficacy and tolerability of a new controlled-release formulation of metoprolol: a comparison with conventional metoprolol tablets in mild to moderate hypertension.

In a double-blind study with parallel groups 195 hypertensive patients were randomly allocated to treatment with either conventional tablets of metoprolol, 100 mg once daily, or a new controlled-release (CR) formulation of metoprolol, 100 mg once daily. The dose was doubled if the patient's diastolic blood pressure remained greater than or equal to 95 mmHg after six weeks on 100 mg, whereas well-controlled patients continued on 100 mg once daily for a further six-week period. In the metoprolol tablet group the 200 mg dose was administered in the form of Durules. There was a significant reduction from the placebo baseline in systolic and diastolic blood pressure and heart rate at 24 h after both six weeks and 12 weeks of active treatment; no significant difference in the mean reduction from baseline between the two groups was demonstrated. However, significantly more patients responded to treatment with metoprolol CR when compared with those patients taking metoprolol tablets. After six weeks of active treatment 61% of the metoprolol CR group and 56% of the conventional metoprolol tablet group had a diastolic blood pressure less than 95 mmHg. After another six weeks the corresponding figures were 83% and 69% respectively. Between week 6 and 12, 36% of patients in the metoprolol CR group and 42% of patients in the conventional metoprolol tablet group were receiving a 200 mg dose. All formulations of metoprolol were well-tolerated. Fewer subjective symptoms were reported during active treatment than during the placebo phase. There were no differences between the groups with regard to changes in laboratory variables from baseline, changes in all combined symptoms, or changes in any one symptom.

Blood Pressure↗

PubMed1988

The antianginal efficacy and tolerability of controlled-release metoprolol once daily: a comparison with conventional metoprolol tablets twice daily.

In a randomized, double-blind, cross-over study treatment with a new controlled-release (CR) preparation of metoprolol, given once daily, was compared with treatment with conventional metoprolol tablets, given twice daily, in 115 patients with stable effort angina pectoris. The patients were treated with 100 mg/day or 200 mg/day, depending on their previous beta-blocker dose. Antianginal efficacy was estimated by counting the number of anginal attacks, by noting the consumption of nitroglycerin tablets, and by exercise tolerance testing. Adverse effects were recorded by a standardized questionnaire. When all patients were analysed together there were no differences in antianginal efficacy between the two treatment regimens. However, when the group taking 200 mg daily was analysed separately better exercise tolerance was found during metoprolol CR therapy, as measured by onset of chest pain and ST-segment change, compared with conventional metoprolol therapy. The two formulations were well tolerated. When given once daily in a total daily dose of 100 mg, the CR preparation induced less adverse effects than the conventional tablets, 50 mg twice daily. It was concluded that the new metoprolol CR preparation, given once daily, possesses the same antianginal efficacy as conventional metoprolol tablets, given twice daily, and may be better tolerated in patients susceptible to side-effects. The antianginal effect of metoprolol CR, 200 mg/day, may be greater over 24 h than that produced by conventional metoprolol tablets, 100 mg twice daily.

Adult↗

PubMed1978

The comparative bioavailability of Lanoxin tablets and Lanoxicaps with and without sorbitol.

(1) The mean cumulative urinary digoxin excretion over 8 days was compared in 8 healthy volunteers after single doses of digoxin administered as 3 Lanoxin tablets of 0.25 mg, 3 digoxin tablets of 0.2 mg, 12 Lanoxicaps without sorbitol of 0.05 mg, 6 Lanoxicaps without sorbitol of 0.1 mg digoxin, 3 Lanoxicaps without sorbitol of 0.2 mg and 3 Lanoxicaps with sorbitol of 0.2 mg. (2) There was no significant difference between the 8 day cumulative urinary excretion for any of the Lanoxicaps treatments. (3) Cumulative urinary excretion after 3 digoxin tablets of 0.2 mg was significantly (P less than 0.05) lower than after all other treatments. (4) Cumulative urinary excretion after 3 Lanoxin tablets of 0.25 mg was not significantly different from that after any of the Lanoxicaps treatments except 0.1 mg Lanoxicaps without sorbitol, it was significantly (P less than 0.05) lower after the latter. (5) Mean urinary excretion of digoxin was 60% of ingested dose for all Lanoxicaps treatments and was significantly (P less than 0.05) higher than the mean value of 50% for both tablet treatments. (6) Enhanced absorption of digoxin from Lanoxicaps was confirmed and shown to be unrelated to the sorbitol content of the capsule shell.

Adult↗

PubMed1984

Gastric emptying of enteric-coated tablets.

To evaluate the gastric emptying time of pharmaceutical dosage forms in a clinical setting, a relatively simple dual-radionuclide technique was developed. Placebo tablets of six different combinations of shape and size were labeled with indium-111 DTPA and enteric coated. Six volunteers participated in a single-blind and crossover study. Tablets were given in the morning of a fasting stomach with 6 oz of water containing 99mTc pertechnetate and continuously observed with a gamma camera. A scintigraph was obtained each minute. The results suggested that the size, shape, or volume of the tablet used in this study had no significant effect in the rate of gastric emptying. The tablets emptied erratically and unpredictably, depending upon their time of arrival in the stomach in relation to the occurrence of interdigestive myoelectric contractions. The method described is a relatively simple and accurate technique to allow one to follow the gastric emptying of tablets.

Adult↗

PubMed1992

Comparison of salivary miconazole concentrations after administration of a bioadhesive slow-release buccal tablet and an oral gel.

The salivary miconazole concentrations after administration of a bioadhesive slow-release buccal tablet and an oral gel have been compared. The bioadhesive tablet consisted of a mixture of thermally modified starch and 5% polyacrylic acid. Although the amount of drug administered via the bioadhesive tablet was sixfold lower than when the gel was used, the salivary miconazole levels were higher and remained above the MIC value of Candida albicans for more than 10 hours. The mean adhesion time of the tablet was 586 min. The bioadhesive tablet appears to be a promising drug delivery system for the buccal administration of drugs for local therapy.

Administration, Buccal↗

PubMedDate not supplied

[Incidence of caries in the Canton Waadt (Vaud) after the change from fluoride tablets to fluoridization of salt].

This report shows results of a survey on dental caries in the Canton of Vaud in the years 1970 and 1974. In this canton fluoridation was carried out by means of fluoride tablets distributed at school until 1969/70 and in subsequent years by adding 250 mg F/kg fluoride to domestic salt. For comparison, results from adjoining and other cantons are also presented. In 1970 the 3 communities in the Canton of Vaud (Moudon, Grandson and Vevey) showed a remarkably low overall caries level due to the distribution of fluoride tablets, supplemented in Grandson with regular brushings with fluoride solution. When the fluoride tablets were discontinued in 1968/70 and fluoridated domestic salt containing 250 mg F/kg NaCl was introduced, caries incidence reached an even lower level. In these 3 communities caries prevalence fell to the lowest level reached, so far, by means of preventive measures in Bettlach (Canton of Solothurn, toothbrushing with fluoride solutions 6 times per year combined with information, fluoride tablets on every school day, and in addition consumption of table salt fluoridated at a suboptimal level of 90 ppm). The children in the control communities Romont (Canton of Fribourg), St-Aubin (Canton of Neuchâtel) and Châtel-St-Denis (Canton of Fribourg) also showed decreases of caries levels from 1970 to 1974. This decrease can be attributed to the distribution of fluoride tablets started at the schools of this community in the late sixties. Caries incidence in the age spans 8 to 12 and 10 to 14 years was estimated. Children from the Canton of Vaud where fluoridated table salt was practically the only preventive measure showed a smaller DMF increase than those from the cantons Fribourg and Neuchâtel. By means of a method combining DMF means of various age groups it was possible to obtain sufficiently large numbers of children for a study of the caries prevalence in each community. All communities showed a decrease of caries levels. In the Canton of Vaud this reduction started at a lower initial level and in 1974 reached consistently lower values than those of the control communities of the cantons of Fribourg and Neuchâtel.

Adolescent↗