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At least 1,081 records · Page 60Linked to original sources
PubMed1987

Bioavailability study of a new amoxicillin tablet designed for several modes of oral administration.

A new tablet of amoxicillin (Flemoxin solutab) has been formulated with galenic properties which allow it to be taken as a tablet, either swallowed, chewed or sucked, or to be taken after dispersion in water. This study was undertaken to compare the bioavailability of the new tablet (swallowed as such, or after dispersion) with a commercially available amoxicillin capsule and, for purposes of internal reference, with a Flemoxin forte suspension. Each formulation was administered to 12 volunteers according to a repeated 4 X 4 latin square design. Statistical analysis revealed that the tablet and suspension formulations tested gave significantly higher maximum plasma levels, occurring significantly faster after intake, when compared to the capsule. Furthermore, the new tablet showed a statistically significantly greater area under the plasma concentration-time curve with a highly predictable absorption when compared to the capsule. The method of intake of the new tablet appeared to be of no relevance with respect to the observed bioavailability.

Administration, Oral↗
PubMed1979

Comparative bioavailability of sustained-release and conventional tablets of hydroxyethyltheophylline in man.

The comparative bioavailability of sustained-release and conventional tablets of hydroxyethyltheophylline was studied in normal subjects. In a single dose study on 7 subjects, 3 conventional tablets or 2 sustained-release tablets were administered orally after a light breakfast and blood samples taken for 6 and 12 hours respectively. With conventional tablets the mean peak concentration (8.10 +/- 0.751 microgram/ml) was reached at 3 hours and concentrations less than 5 microgram/ml were observed in 4 out of 7 subjects at 6 hours. In contrast, with sustained-release tablets of theophylline and hydroxytheophylline complex the mean peak concentration (8.90 +/- 0.88 microgram/ml) was reached at 6 hours and levels above 5 microgram/ml were observed in 4 out of 7 cases at 12 hours. Administration of 2 sustained-release tablets twice a day produced trough plasma concentrations varying between 6.9-13.8 microgram/ml, i.e. within the therapeutic range in all the 5 subjects. It is concluded that this new oral sustained-release preparation provides therapeutic plasma theophylline concentration on a 12 hourly dosage schedule.

Biological Availability↗
PubMed1983

Stability of nitroglycerin tablets submitted by U.S. hospitals.

The stability of nitroglycerin tablets that had been stored in hospitals across the United States was studied. Through a voluntary FDA drug stability program, all hospital pharmacies in the United States were asked in October 1981 to complete a response card indicating information about nitroglycerin tablets they had in stock. Based on the responses, FDA selected 167 samples (representing three manufacturers and all available tablet strengths) from pharmacies that represented an adequate cross section of the country. The samples were analyzed for content uniformity, strength, identification, and disintegration; samples that left a residue on the screen of the tablet disintegration basket were tested for dissolution by three methods and compared with samples that did not leave a residue. All samples met USP requirements for content uniformity, strength, and disintegration. Six samples that showed unusual disintegration characteristics dissolved slowly by one or more methods; however, other samples also showed slow dissolution. Nitroglycerin tablets appear to be stable when stored under actual marketplace conditions. The USP disintegration test will not distinguish between rapidly and slowly dissolving tablets.

Drug Stability↗
PubMed1984

[Use of polyacrylate dispersions for nebulization of phenobarbital. 2. In vitro testing of tablets with phenobarbital polyacrylate microspheres].

Using factorial design the authors investigate the qualification of phenobarbital microcapsules with polyacrylate to produce retard tablets. The drug release of the tablets depended significantly on the pressure, the drug concentration and the form of the tablets (microcapsules or corresponding physical mixtures of the ingredients. The drug release from the tablets with microcapsules was more slowly than from tablets with physical mixtures, because there are additional barriers and the formation of a more fixed matrix. The increase of the polyacrylate (from 20 up to 40%) and of the pressure (from 50 up to 100 MPa) inhibits significantly the drug release from the matrices. REM-pictures explain the structure of the tablet surfaces before and after the liberation test.

Acrylic Resins↗
PubMed1984

Pharmacokinetics and bioavailability of metronidazole after tablets, suppositories and intravenous administration.

The pharmacokinetics of metronidazole were determined in cross-over study on 11 healthy volunteers after 400 mg tablets from two producers. 1000 mg suppositories and 800 mg intravenously (IV). High-pressure liquid chromatography was used to assay both unchanged metronidazole (M) and the hydroxy metronidazole metabolite (OH-M). The peak concentrations were observed 1.2 - 1.3 hrs after the administration of tablets and 4.9 hrs after the suppositories. After the IV dose, the OH-M peak appeared only after 8 hours. The serum half-life was 6.5 hrs after the IV dose, 6.1 - 6.8 hrs after the tablets and 6.8 hrs after the suppositories. After IV dosage, the terminal phase distribution volume was 38.1 lit and the total body clearance 4.09 lit/hr. The bioavailability of the tablets was 80.4 and 84.1 per cent and after the suppositories 53.8 per cent. The rate of elimination OH-M was faster after suppositories than after IV dosage where it was intermediate after the tablets. Accordingly, the serum-half-life was 9.7 hrs after suppositories, 19.2 hrs after IV infusion, and 10.6 and 11.8 hrs. after the tablets. The rates of apparent metabolization was graded in the same relative order, with a faster rate after the suppositories, 0.168 hrs-1 compared to 0.368 hrs-1 after the IV route of administration. The differences pertaining to OH-M is considered probably to be caused by interaction with the metabolic activity of the bacterial flora of the colon.

Absorption↗
PubMed1984

[Use of foaming and nonfoaming gentamycin tablets in treating cows with chronic endometritis].

Biopharmaceutic and therapeutic investigations were carried out with foaming and nonfoaming gentamycin sulfate tablets. The experiments were conducted with a total of 100 cows affected with chronic inflammation of the uterus. Both types of tablets, containing 30,000 IU of gentamycin sulfate each were introduced into the uterus via Andreev's catheter, bimanually or by means of a vaginal speculum and Albrechtzen's clamp, at the rate of 10. Followed up were the serum levels, the excretion with the milk, and the content in the uterine secretion of gentamycin after using the tablets. There was no statistically significant difference in the serum levels of gentamycin as initiated by the two types of tablets. In milk the peak values reached 0.02 micrograms/cm3, and in uterine washings (with 15 cm3 isotonic solution of sodium chloride) the proper levels were established up to 74nd hour. Demonstrated was the therapeutic effect in the treatment of cows with chronic endometritis - 77.4 per cent with the use of foaming and 71.4 per cent with the use of nonfoaming tablets. There was also a rising trend with the conception rate in the treatment of sterile cows (otherwise having no signs of uterine inflammation) with the use of nonfoaming tablets of gentamycin sulfate at the rate of 5, introduced 24 hours after insemination.

Animals↗
PubMed1980

Pharmacokinetics of whole and half Theo-Dur tablets.

The bioavailability and absorption patterns of whole and divided sustained-release theophylline tablets, Theo-Dur, were investigated. Both whole and divided tablets were well absorbed. The rates of absorption differed. The mean absorption time for whole tablets was 5.7 h and for divided tablets 4.2 h. The influence of these differing mean absorption times on the appearance of the serum curves is negligible, and the sustained action is maintained also after breaking the tablets. The present investigation shows that Theo-Dur tablets can be broken for dosage convenience, still maintaining the sustained action.

Adult↗
PubMed1982

Steady-state plasma levels of salicylate in patients with rheumatoid arthritis: effects of dosing interval and tablet strength.

Forty patients who were admitted to hospital with rheumatoid arthritis received a total of 3.9 g/d of enteric-coated acetylsalicylic acid (ASA) (Entrophen) according to one of four dosing schedules: group 1 (n = 13), three 325-mg tablets four times daily; group 2 (n = 11), two 650-mg tablets three times daily; group 3 (n = 10), three 650-mg tablets twice daily; and group 4 (n = 6), two 975-mg tablets twice daily. Five to seven days after the start of therapy, when steady-state plasma salicylate levels had been achieved, 10 blood samples, 1 per hour, were collected. Three healthy volunteers who received plain ASA formed a control group. There was little fluctuation in the salicylate levels over the sampling period, regardless of the dosing interval, and no significant difference in the fluctuations between the five groups. Likewise, there was no significant difference in the mean salicylate levels at each sampling time, regardless of the dosing interval or tablet strength. These results suggest that different tablet strengths of enteric-coated ASA and different dosing intervals produce comparable plasma salicylate levels. Less frequent dosing may improve patient acceptance of salicylate therapy in the treatment of arthritis.

Adult↗
PubMed1982

[Barbital buffer in tablets as a solvent for complement fixation test (CFT)].

The purpose of this paper was to develop a tableting technology of barbital buffer as a standard diluent easy in use for complement fixation test (CFT). As starting point, barbital (veronal) buffer after Alton et al. [1] was assumed. Among 4 solubilizers polyvinyl pyrrolidone (PVP 10 000) was chosen, which provided a good solubility of the barbital in distilled water at 20 degrees C and it affected favourably the complement activity (C'). PVP 10 000 added to the components of barbital buffer at an amount of 0.275 per 10 tablets, in the form of solution for granulation, provided the required physical properties of the tablets. As compared with the barbital buffer after Alton et al. [1], the tablets produced affected favourably C' activity, decreased the range of spontaneous haemocyte lysis, and they did not effect CFT titers of two anti-Brucella abortus standard sera as well as 77 sera of cattle infected with brucellosis under natural conditions. The described physical and biological properties of the barbital buffer tablets with PVP addition indicate their usability as diluent for CFT. A standard diluent used in the form of tablets in all Poland's laboratories should provide a better reproducibility of CFT results in diagnostic examinations towards brucellosis as well as other infectious diseases in men and animals.

Animals↗
PubMedDate not supplied

Comparative bioavailability of chlorpropamide tablet and suspension formulations.

The bioavailability of a chlorpropamide tablet formulation chlorpropamide tablet formulation was assessed by comparing it to a reference suspension of chlorpropamide. Eighteen healthy adult men received chlorpropamide 250 mg as a tablet (Diabinese, Pfizer) and suspension in an open two-way crossover study of Latin-square design with a 14-day washout period between treatments. Serial blood samples were obtained by venipuncture for 96 hours for chlorpropamide serum concentration determinations. Serum glucose concentrations were determined at 0, 0.5, 1, 2, and 4 hours. The area under the serum chlorpropamide concentration-time curve (AUC), peak serum chlorpropamide concentration (Cmax), time to Cmax, and mean glucose concentration at each time point for each treatment were compared using a two-tailed Student's t test for paired data (p less than 0.05). Microrate constants for a two-compartment model for oral absorption computed using nonlinear regression were also compared. There were no significant differences between the two formulations regarding AUC, Cmax, time to Cmax, and hypoglycemic response. The absorption rate for the tablet was significantly greater than for the suspension. The results suggest that the oral chlorpropamide tablet and reference suspension are bioequivalent. Although the tablet had a faster absorption rate than the suspension, this probably is not clinically important since both formulations similarly decreased serum glucose concentration.

Adult↗
PubMed1980

Effect of formulation on dissolution and bioavailability of phenytoin tablets.

Bioavailability of different phenytoin tablets was calculated from saliva phenytoin levels in healthy human volunteers in a single dose study. Tablets containing different excipients and either phenytoin free acid or sodium phenytoin were chose on the basis of an in vitro dissolution rate study of different tablets. Tablets containing phenytoin precipitated with polysorbate 80 showed faster in vitro dissolution and also higher bioavailability than tablets prepared with phenytoin free acid with different excipients. In vivo studies showed that proper formulation of a tablet containing the free acid form of phenytoin can give rise to the same bioavailability than that of sodium phenytoin. In vitro dissolution of the formulation reflected in vivo bioavailability.

Adult↗
PubMed1993

Comparison of the effect of a single oral L-thyroxine dose (150 micrograms) in tablet and in solution on serum thyroxine and TSH concentrations.

150 micrograms of L-thyroxine were administered to each of 14 euthyroid goitrous patients orally between 7:30 and 8:30 a.m. after fasting overnight. The L-T4 dose given was one and half tablets of the drug "Eutirox" (L-T4 tablet of 100 micrograms distributed by Bracco, Milan, Italy) or one and half ml of the solution "Tiroxen" (solution containing 100 micrograms/ml of L-T4 distributed by Laboratori Baldacci, Pisa, Italy). Two studies (one with tablet and one with solution) were performed on each patient. The tablet or the liquid form of L-T4 were administered in random order. In each study a blood sample for serum hormone determination was drawn immediately before L-T4 administration, then 30 minutes later and every hour up to the fifth hour after. The second study was performed in similar fashion later. The mean serum TT4 concentration value at any time was very similar in the two studies, thus showing the same time course after the administration of solution and the tablet formulation. The mean basal TT4 value (9.07 +/- 0.56 and 8.90 +/- 0.73 micrograms/dl respectively) increased significantly at the first and second hours. The highest value was reached at the second and at the third hour after the solution (11.15 +/- 0.58 micrograms/dl) and the tablet (11.81 +/- 0.78 micrograms/dl) respectively. Subsequently, the mean TT4 values remained significantly higher than basally over the entire 5 hours. The FT4 mean serum concentration at all times were very similar in the two studies and showed the same time course.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Relative bioavailability of iron from two different iron tablets used in the Indonesian Iron Supplementation Program.

The relative bioavailability of two different iron tablets which are used in the Indonesian iron supplementation program was determined, because low bioavailability of iron might decrease the impact of the program. In two studies volunteers (n = 12, n = 6) received 120 mg elemental iron either as two iron tablets, each containing 60 mg elemental iron, or as an aqueous Fe(II)-sulphate solution in a randomized cross-over design. Plasma iron concentrations were measured before, and 1, 2, 4, 6, 8 and 10 hours after dosing. For each of the tablets and solutions, the positive area under the concentration/time curve (AUC+), the peak plasma level (Cmax), the time to reach the peak plasma level (tmax) and the relative bioavailability were determined. Relative bioavailability of both tablets was high (106.9 +/- 24.3%) and 116.3 +/- 43.1%). This indicates a good therapeutical efficacy of both tablets. In case where low effectiveness of iron supplementation programs is recorded, factors other than low bioavailability of iron in the tablets must be responsible.

Adult↗
PubMed1994

Antacid activity of calcium carbonate and hydrotalcite tablets. Comparison between in vitro evaluation using the "artificial stomach-duodenum" model and in vivo pH-metry in healthy volunteers.

Antacid activity of calcium carbonate (CAM, Rennie) and of hydrotalcite (HYD) containing tablets has been assessed in vitro using computer-controlled "artificial stomach-duodenum" model, including or not a piece of hog gastric mucosa in the gastric reservoir, and simulating the constant flux system or the normal gastroduodenal flux regulation. The data obtained under the latter condition were compared to those obtained in vivo by pH-metry in 12 healthy volunteers, in response to one administration of 2 tablets. The theoretical maximal capacity was similar when 1 tablet of CAM or of HYD was added to the gastric contents, including or not a piece of gastric mucosa, close to 95 H+ mmol. The reduction of acid load penetrating into the duodenum and the duodenal pH were of the same magnitude in response to both antacids. When normal gastroduodenal flux regulation was simulated, a dose-response curve, constructed by 1, 2 or 3 tablets, resulted in the same antacid characteristics in response to both antacids. The maximal gastric and the mean duodenal pH values obtained with CAM were, however, higher than with HYD, corresponding to a greater neutralizing activity developed by CAM than by HYD. The comparison between in vivo administration of two tablets of each antacid and the in vitro model simulating normal gastroduodenal flux regulation in response to the addition of two tablets resulted in similar data. The maximal pH values obtained in in vivo assays were slightly lower than in vitro, depending on the ratio of antacid amount to gastric acid content, well established in in vitro conditions and unknown in in vivo situations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Use of galactomannan to produce hydrophilic matrix tablets].

Galactomannan currently seems to be a very promising auxiliary. The aim of the present work was to examine the applicability of this auxiliary in tablet-making. Galactomannan is a polysaccharide composed of galactose and mannose, which is distributed by the Swiss firm Meyhall under the name Meyprogat. The products are numbered according to their molecular weight and polymeric degree. Thus, Meyprogat 7, 30, 60, 90, 120 and 150 can be discriminated. It is used in many areas, for example in the food industry as a stabilizing agent, and in medical therapy to cure diabetes and hyperlipidaemia. In pharmaceutical technology, it is used in low concentration (5-10%) as a disintegrant agent and in high concentration (25%) as binding agent. It is able to form a hydrophilic matrix, which results in sustained release. Theophylline was chosen as model agent. After the preformulation examinations, granulations were made by a wet method, and after this tablets were formed. Examinations were made of the granulations, the physical parameters of the tablets were determined, and the release of the effective agent from the tablets was studied. The following conclusions were drawn: 1. Galactomannan yields tablets with very good hardness. 2. Galactomannan is suitable for the formation of hydrophilic matrix tablets. Through use of this macromolecular agent, the rate of dissolution can be influenced in accordance with the desired purpose.

Carbohydrate Conformation↗
PubMed1993

A comparison of low dose methotrexate bioavailability: oral solution, oral tablet, subcutaneous and intramuscular dosing.

OBJECTIVE: To compare the relative bioavailability of low dose methotrexate (MTX) administered as tablet, oral solution, and subcutaneous (sc) injection to that of intramuscular (im) injection in patients with rheumatoid arthritis (RA). METHODS: Twelve patients meeting the American College of Rheumatology criteria for RA had serial blood MTX concentration samples drawn over a 24-h period after receiving their normal weekly MTX dose. Relative bioavailability (F) of the tablet and oral solution formulations was determined by comparison of the area under the time-versus-serum-concentration curves (AUC) for the 2 different oral formulations as a percentage of the AUC for im injection. Also, relative bioavailability of the sc formulation was compared to im in 6 of the patients. RESULTS: Mean F for the oral tablet was 0.85, while that for the oral solution was 0.87. Both oral formulations showed a statistically significant difference in mean F when compared to im (tablet vs im, p = 0.002, oral solution vs im, p = 0.009). No statistically significant difference, however, was found in mean relative bioavailability between tablet and solution (p = 0.744). The mean F for sc was 0.97; no statistically significant difference existed between the mean F values for the sc and im routes of administration (p = 0.657). CONCLUSIONS: Our data suggest the oral solution may be substituted for tablet dosing and sc injection substituted for im. Thus, a variety of different dosing methodologies may be considered providing the most appropriate route in each patient, given issues of compliance, medication cost, and preference.

Administration, Oral↗
PubMedDate not supplied

Determination of reserpine and chlorothiazide in commercial tablets by liquid chromatography with fluorescence and UV absorbance detectors in series.

A procedure is presented for determination of reserpine and chlorothiazide in commercial tablets by liquid chromatography (LC). Powdered sample, equivalent to the weight of one tablet, is dissolved in 10.0 mL dimethyl sulfoxide, the mixture is diluted to 100.0 mL with methanol, and the solution is filtered; 10 mL of the filtrate is then diluted to 100.0 mL with methanol. The standard solution is prepared in the same solvent mixture and contains the 2 ingredients in approximately the same quantities as in the diluted sample solution. For LC, a 7.5 cm long normal-phase column is used; mobile phase consists of methanol containing a small volume of an aqueous solution of 1-pentanesulfonic acid, sodium salt. Two detectors are arranged in series: a fluorescence detector set at 280 nm excitation and 360 nm emission quantitates reserpine and a UV absorbance detector set at 300 nm determines chlorothiazide. Several synthetic mixtures containing the 2 ingredients in amounts ranging from 80 to 120% of quantities declared in commercial tablets were analyzed by the proposed method. Two samples of commercial tablets were also analyzed; for each sample, 5 determinations were made on a ground composite of 20 tablets; 10 individual tablets were also analyzed. The composites were also analyzed by the current U.S. Pharmacopeia method for this product.

Antihypertensive Agents↗
PubMed1996

Comparative bioavailability of a metoprolol controlled release formulation and a bisoprolol normal release tablet after single oral dose administration in healthy volunteers.

The bioavailability patterns of a 100 mg metoprolol controlled release tablet and a 10 mg bisoprolol normal release tablet were compared in a single dose crossover study in 12 healthy subjects. The plasma drug concentration levels were measured for 36 h post-dose, using HPLC with fluorimetric detection. The 2 formulations were equally well tolerated, headache being the most frequently reported adverse event. Episodes of bradycardia (heart rate < 50 bpm) occurred at a similar rate with both formulations. The plasma metoprolol profile differed significantly (p < 0.05) from the bisoprolol profile regarding time to maximum concentration, mean residence time, the ratio of peak concentration (Cmax) to the area under the curve (AUC) and the plateau time as estimated from the half-value duration. The average drug plasma concentration observed 24 h after administration still accounted for 54% of the Cmax value for the metoprolol controlled release tablet, but only 23% with the bisoprolol normal release tablet. A large inter-individual variability was seen in the bioavailability of metoprolol, with 3 subjects (characterised as CYP2D6 deficient) exhibiting AUC values 8 - 10 times larger than in the other subjects. The controlled release pattern of the formulation was similar in slow and fast metabolizers. No such variability pattern was apparent for bisoprolol. The findings allow to conclude that, after administration of the metoprolol controlled release tablet, the rate of absorption of the active principle is significantly slower, therefore yielding more constant plasma concentration levels over the 24 h post-dose period, than after administration of the bisoprolol normal release tablet.

Absorption↗