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PubMed1975

Pharmacokinetics of procainamide intravenously and orally as conventional and slow-release tablets.

Pharmacokinetics of procainamide were studied in healthy volunteers after single doses intravenously and orally as conventional and slow-release tablets and after repeated oral doses to steady state. The initial distribution after intravenous administration was rapid and the overall elimination in the beta-phase corresponded to t1/2 of 2.7 hr. The mean volume of the central compartment was small and only 4 percent of V-d (beta), which was 2.3 l/kg body weight. About 65 percent was excreted unchanged after intravenous administration and about 55 percent after a single oral dose of 500 mg. The recovery of the metabolite N-acetylprocainamide was 12 percent after both routes of administration. Procainamide was completely absorbed from the gastrointestinal tract and the first-pass elimination was very limited. The rates of absorption from the tablet compositions were well correlated to the in vitro dissolution properties. Administration of slow-release tablets every 8 hr gave about the same mean plasma level at steady state as ordinary tablets given every 4 hr, and the availability was the same from both preparations. The occasional high plasma concentration peaks after ordinary tablets were not observed after the slow-release tablets. Renal clearance was about 500 ml/min, indicating an active secretion in the tubules.

Acetylation↗

PubMed1989

Effect of a high-fat meal on the bioavailability of a polymer-coated erythromycin particle tablet formulation.

The effect of food on the relative bioavailability of an erythromycin particles-in-tablet formulation was studied in 27 healthy volunteers, using a four-way, crossover study design with the following treatments: one or two erythromycin capsules USP (Eryc, Parke-Davis), or one polymer-coated erythromycin particles-in-tablet (PCE, Abbott) administered fasting or with a high-fat meal. Under fasting conditions the erythromycin particles-in-tablet and erythromycin capsule formulations are bioequivalent based on similar tmax and dose-normalized Cmax and AUC values. The rate and extent of absorption from the particles-in-tablet formulation, however, are dramatically reduced following administration with a meal. Mean Cmax and AUC values decreased by 73% and 72%, respectively, and seven subjects had no detectable erythromycin plasma concentrations for 16 hours following administration of the particles-in-tablet formulation with the high-fat meal. Greater than 40% of the subjects had nonfasting Cmax and AUC values that were less than 10% of those values following administration of the dose fasting. Cmax and AUC values in nonfasting subjects were within 75% to 125% of fasting values in only two and one of 27 subjects, respectively. The erythromycin particles-in-tablet formulation therefore should not be administered with meals.

Adult↗

PubMed1995

The effects of calcium supplementation (milk powder or tablets) and exercise on bone density in postmenopausal women.

The etiology of age-related bone loss is unclear but both lack of exercise and dietary calcium deficiency have been implicated in its causation. This 2-year randomized placebo-controlled study was designed to examine the effects of increased dietary calcium and exercise in 168 women who were more than 10 years postmenopausal. The subjects were randomized into one of 4 groups: placebo, milk powder containing 1 g of calcium, calcium tablets 1 g/night, and calcium tablets 1 g/night and an exercise regimen. The exercise group aimed to undertake 4 h of extra weight-bearing exercise per week and were undertaking 10% more activity than other groups at 2 years. Bone mineral density at the lumbar spine, three hip sites, and two sites of the tibia close to the ankle joint were measured at 6 month intervals. Dietary intake was evaluated by a weighed food record, exercise was evaluated by an exercise diary, and blood and urine samples were obtained to examine effects on calcium homeostasis. Individual data points were compared using repeated measures ANOVA and least squares regression. Calcium supplementation by either the calcium tablets or the milk powder resulted in cessation of bone loss at the intertrochanteric hip site (placebo, calcium tablets, calcium and exercise, milk powder -0.81, +0.17, +0.23, and +0.07% per year, respectively; p < 0.05 for all supplementation groups compared with placebo) with similar results at the trochanteric hip site. The calcium and exercise group had less bone loss at the femoral neck site when compared with calcium supplementation alone (placebo, calcium tablets, calcium and exercise, milk powder -0.67, -0.18, +0.28, and -0.18% per year, respectively; p < 0.05 for calcium and exercise compared with calcium alone). There was a significant reduction in the rate of bone loss at the ultradistal site of the tibia (placebo, calcium tablets, calcium and exercise, milk powder -2.5, -1.6, -1.0, and -1.5% per year, respectively; p < 0.05 for all supplementation groups compared with placebo). There was no significant bone loss at the spine site in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed2003

Characterization of physical mixtures and directly compressed tablets of sulfamerazine polymorphs: implications on in vitro release characteristics.

The present study evaluates the effects of excipients, compression pressure, and relative humidity (RH) on the stability of sulfamerazine polymorphs (referred here as SMZ I and SMZ II) and their release from directly compressed tablets using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and dissolution analysis. SMZ I and SMZ II tablets were compressed with magnesium stearate (MGST), and microcrystalline cellulose (MCC) at 5000, 7500, and 10,000 lbs. pressures and stored at 40, 75, 95, and 100% RH conditions for 5 weeks. There were indications of possible drug-excipient interaction in the binary mixtures under different relative humidity conditions from the DSC data, but they could not be confirmed by PXRD because the crystal structures of the drug and excipients remained unaltered. The crystal structures of the polymorphs in the tablet also remained unaltered under the above conditions. There were, however, significant differences observed in the drug release properties of the two polymorphs. SMZ II was found in general to have a higher rate of drug release than SMZ I. Extensive gelation of MCC under higher moisture conditions, compression pressure during tableting, and inherent tabletability of the sulfamerazine crystals were factors that affected drug release. All these factors contributed towards prolonging the disintegration and deaggregation of the tablet particles and were therefore concluded to be the rate limiting steps for the dissolution process.

Anti-Infective Agents↗

PubMed2003

Characteristics of hydroxypropyl methylcellulose influencing compactibility and prediction of particle and tablet properties by infrared spectroscopy.

Particle characteristics, chemical substitution, compaction behavior, and tablet properties of hydroxypropyl methylcellulose powders from two different suppliers were related using multivariate data analysis. By Principal Component Analysis it was shown that the the degree of substitution of the HPMC powders did not correlate to the particle and compaction properties as strongly as anticipated. Particle shape and powder surface area seem to be more important for the compaction behaviour of the powders than the degree of substitution. In addition, particle and tablet properties were predicted from infrared spectral data. Fourier transform infrared (FTIR) and near infrared (NIR) spectral data of the powders were combined with measured values of the particle characteristics, compaction behavior, and tablet properties using the multivariate data analysis program SIMCA 7.1. Properties like density, particle shape, tablet tensile strength, and drug release characteristics of the HPMC powders and corresponding tablets in this study could be predicted using Partial Least Squares models. In conclusion, the particle shape and powder surface area of HPMC powders seem to be important factors for the quality of tablet attained. Further, this study confirms that NIR and FTIR analysis used in combination with multivariate analysis are powerful tools for predicting the properties of materials and the quality of the end product.

Compressive Strength↗

PubMed2003

Tensile strength and disintegration of tableted silicified microcrystalline cellulose: influences of interparticle bonding.

The effects of some material variables (particle size and moisture content) on the tensile strength and disintegration time of tableted standard microcrystalline cellulose (MCC, Avicel) and a silicified brand (SMCC, Prosolv) were studied. Three particle size fractions were employed, after equilibration in three levels of environmental relative humidity (RH%), and the tensile strength and disintegration time were determined at different levels of total tablet porosity or packing fraction (p(f)). The MCC grade or silicification affects the moisture sorption and the packing during tapping as well as the particle deformation (yield pressure, P(y)) during tableting. There was a slight increase in the tensile strength but a marked increase in the disintegration time of Prosolv compared with Avicel in the p(f) range 0.7-0.9, which corresponds the range for pharmaceutical tablets. These increases are explained in terms of the range and magnitude of the interparticle forces developed and the interparticle separation. Despite the higher moisture content of Prosolv after equilibration compared with Avicel, compression of Prosolv results in higher P(y), in tablets of higher energy of interparticle bonding, longer interparticle separation, and extended disintegration compared with Avicel. The incorporated SiO(2) is thought to play the role of barrier or sink for the moisture sorbed, but only for RH up to 52%, which is a moisture content range less than twice that of tightly bound water. At higher RH (72%), the incorporated SiO(2) does not increase the P(y), but reduces the energy of interparticle bonding and the interparticle separation because of its probable saturation. The latter, in turn, results in more extended disintegration times due to reduced uptake of water into the tablets and to the probable reduction of water available for the deployment of the microcrystalline cellulose activity as disintegrant.

Cellulose↗

PubMed2005

Release of poorly soluble drugs from HPMC tablets studied by FTIR imaging and flow-through dissolution tests.

Spectroscopic imaging and a flow-through dissolution test have been combined to improve the possibilities of investigating the release of a poorly soluble drug (diclofenac) from pharmaceutical tablets. The presented methods aim to overcome the limitations that impede the conventional dissolution test because of its inability to observe precipitates of poorly soluble drug during tablet dissolution. The proposed flow-through set-up allows small drug particles that are being carried along in the water-flow to be analyzed, by adding a dissolution agent to the medium after it left the tablet cell. Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopic imaging provides an insight into the processes inside the tablet and is not hindered by insoluble or recrystallising drug. The techniques have been hyphenated and used to study tablets containing diclofenac sodium and HPMC (hydroxypropyl methylcellulose) in different dissolution media that influence the solubility of the drug. The release profiles obtained by flow-through dissolution test suggest the presence of particles (or precipitates) in the dissolution medium. This is consistent with the results obtained by FTIR imaging, which confirms that both proposed techniques are superior to the ordinary dissolution test when applied to poorly soluble drugs. FTIR imaging data have been analyzed by a classical least squares analysis, corrected for the parts of the tablet outside the field of view, and used to calculate the release profile. The infrared spectra of diclofenac at varying relative humidity were acquired to study the interactions of diclofenac and water, including identification of dissociated diclofenac, thus the chemical specificity of FTIR imaging was fully utilized.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1976

Vapor pressure of nitroglycerin in sublingual molded tablets: implications for stability.

To understand nitroglycerin intertablet migration, vapor pressures of nitroglycerin in tablets were measured using a modified gravimetric Knudsen effusion technique. To supplement the vapor pressure data, adsorption isotherms at 296 degrees K were determined, and tablets were studied by scanning electron microscopy. For conventional tablets (i.e., tablets without stabilizing additives such as polyethylene glycol 400), the nitroglycerin vapor pressure in a tablet is within about 10% of that for pure liquid nitroglycerin, provided the potency is greater than 0.3 mg. Significant capillary condensation in tablets at relative vapor pressures close to unity is demonstrated. Stabilizing additives lower the vapor pressure of nitroglycerin, the magnitude of the effect depending on both the nature of the additive and the additive-nitroglycerin weight ratio. The mechanism of intertablet migration involves capillary condensation. Vapor pressure reduction of about 15%, achieved through the use of an additive, appears sufficient to prevent significant intertablet migration.

Adsorption↗

PubMed1984

Systematic error associated with apparatus 2 of the USP dissolution test V: Interaction of two tableted prednisone formulations with glass and plastic vessels.

Recently marketed glass vessels that are uniform and pass USP specifications were compared with uniform plastic vessels that also pass USP specifications. Two lots of prednisone tablets, Tablet 1 and Tablet 2, were tested in both types of vessels. Tablet 1 gave higher results (+12.7% of label claim) in glass vessels at 50 rpm but gave equivalent results in either vessel at 75 rpm. Tablet 2 gave equivalent results in either vessel at 50 rpm but gave higher results (+22% of label claim) in glass vessels at 75 rpm. The type of vessel used to obtain dissolution results for tablets should be specified.

Chemistry, Pharmaceutical↗

PubMed1990

What happens to tablets and capsules in the stomach: endoscopic comparison of disintegration and dispersion characteristics of two microencapsulated potassium formulations.

Previously we investigated gastric emptying and distribution of a capsule formulation of microencapsulated KCl and found the drug was usually present in clumps of KCl crystals held in place by gastric mucus. We therefore investigated whether a tablet formulation of microencapsulated KCl would have improved dispersion. We characterized the intragastric disintegration of capsules and tablets of microencapsulated KCl in 12 subjects. The capsule formulation floated in the gastric pool; one end would adhere to the gastric mucosa and the motion of the tethered capsule would pull the end of the capsule off. The KCl crystals would then be deposited in a mass. In contrast, the tablet formulation sank to the anatomically most dependent portion of the stomach. The tablet rapidly became soft and fragile but, if allowed to remain in one place and minimally disturbed, required a median of 12 min to lose its shape. If allowed to reach the gastric antrum, the tablet was quickly ground by the antro-pyloric pump and widely dispersed. Once liberated in the stomach, the microencapsulated KCl crystals were bound into a more-or-less cohesive mass. The differences between KCl formulations, once the crystals were released, was minimal although the larger crystals from the tablet formulation appeared less adherent and cohesive; they dispersed more in a reticulated pattern when the stomach was distended. We conclude that formulation of a drug in a microencapsulated multiple-unit dosage form does not guarantee wide dispersion nor absence of high local concentration of drug.

Adult↗

PubMed1992

Novel approach to estimate quality of binary random powder mixtures: samples of constant volume. II: Applications of equation to optimize tableting conditions.

In a companion communication, an equation (eq 1) of the homogeneity of binary random mixtures, which applies to constituents differing in particle size and in bulk density, was derived. The present paper demonstrates the practical applications of this equation in optimizing tableting conditions with respect to a high dose uniformity. Tablets of 50:50 (w/w) mixtures of coarse sucrose and of fine microcrystalline cellulose (Avicel PH 101)-talc vehicle were produced on a single-punch machine. Without a spin feeder, the tablets showed variations in content uniformity that were significantly higher than those estimated from eq 1. Correlation analysis between the individual mass and the content of the constituents of the tablets revealed this difference to be due to nonuniformity of the die filling and not due to incomplete mixing. Accordingly, the use of a spin feeder allowed production of tablets with higher dose uniformity, which conformed well with the theoretical optimum predicted with eq 1. Further variation of the processing conditions cannot improve the quality (i.e., varying the tableting speed resulted in equal or in poorer uniformity of dose content).

Algorithms↗

PubMed1994

Pharmacodynamics and relative bioavailability of cabergoline tablets vs solution in healthy volunteers.

The effect of formulation on the urinary pharmacokinetics, pharmacodynamics, and relative bioavailability of cabergoline was investigated. Twelve healthy female volunteers, aged 23-35 years, were treated, according to an open, randomized, crossover design, with cabergoline (1-mg single oral dose) both as tablets and as a solution. The two administrations were separated by a 4-week wash-out period. Cabergoline and prolactin were measured in urine and plasma, respectively, by specific radioimmunoassays. Blood samples were collected before and up to 30 days after dosing. Urine was collected before and up to 8 days after dosing. Cabergoline elimination half-lives calculated from urinary data were 68 and 63 h after administration of the tablets and the solution, respectively. Urinary excretion of unchanged cabergoline accounted, on average, for 1.92% (range, 0.14-3.26) and 1.80% (range, 0.67-3.09) of the dose after administration of the tablets and the aqueous solution, respectively. Relative bioavailability of tablets vs solution was 99% (geometric mean with the 90% confidence intervals of 68-144%). Prolactin levels in 10 out of 12 subjects fell below the detection limit of the assay (1.5 micrograms/L) after both treatments. The mean maximum prolactin decrease (ca. 70%) was achieved by 2 or 3 h after dosing; the effect persisted up to 9 days, being completely exhausted 23-28 days after dosing. The analysis of variance performed on the pharmacodynamic effects of the two cabergoline formulations indicated that the percent decreases of plasma prolactin levels were not significantly different for tablets and solution. These results indicate that the pharmacodynamics and relative bioavailability of cabergoline are not influenced by formulation, as tablets or solution.

Adult↗

PubMed1990

Comparative bioavailability of a cisapride suppository and tablet formulation in healthy volunteers.

The comparative bioavailability of cisapride as a 30 mg suppository and three 5 mg oral tablets was investigated in 12 non-smoking, healthy male volunteers. The two formulations were administered on two separate occasions following an overnight fast, according to a randomized cross-over design. The plasma concentration of cisapride was measured over 48 h after drug administration. The 30 mg suppository exhibited a mean time to the peak plasma concentration of 3.8 h, while the tablets showed a significantly earlier peak time of 1.5 h. The maximum plasma concentration of cisapride after the 30 mg suppository (50.3 ng.ml-1) was significantly lower than after the tablets (74.3 ng.ml-1). The AUCs following the two treatments did not differ significantly from each other. The comparative bioavailability of the 30 mg cisapride suppository in relation to the three 5 mg oral tablets was 85%, with a 95%-confidence interval of 67% to 102% (not adjusted for dose). Normalizing the mean AUC by dose, the relative bioavailability of the suppository was 43% of that of the tablet. The elimination half-life of cisapride was not significantly different following the administration of the two formulations (9.3 h for the suppository and 9.8 h for the tablet).

Adult↗

PubMed1981

Amitriptyline pharmacokinetics. Single doses of Lentizol compared with ordinary amitriptyline tablets.

Two separate single doses of Lentizol (W. R. Warner, Pontypool, U.K.), a sustained-release preparation of amitriptyline (AT) were taken by each of six healthy subjects. Plasma concentrations of AT and of nortriptyline (NT) were determined at intervals over a period of 48 or 72 h. Faeces were collected and their drug content measured. Results were compared with those obtained when the same subjects took ordinary AT tablets. AT was found in the faeces after the ingestion of Lentizol or of ordinary AT tablets. However, after NT tablets negligible amounts of NT appeared in the faeces. AT was sometimes absorbed slowly from Lentizol, but on other occasions it was absorbed as rapidly as from ordinary tablets. Plasma levels of AT 24 h after the dose were usually not higher after Lentizol than after an equal dose of ordinary tablets. The systemic bioavailability of Lentizol as judged by areas under the plasma concentration-time curves, both for AT and for the NT formed metabolically, was on average lower than that of the ordinary tablets. However, the amounts of AT found in the faeces were not large enough to account for the AT area reduction by simple failure of absorption. Possible explanations of the discrepancy are discussed.

Amitriptyline↗

PubMed1981

In vitro release and in vivo serum fluoride levels and urinary excretion after different sodium fluoride tablets.

Various sodium fluoride tablets used for the treatment of osteoporosis were evaluated. The tablets were characterized in vitro by determining the release curves. The serum levels and urinary recovery of fluoride were determined after a single oral dose either of rapidly soluble (conventional), sustained release or enterocoated tablets. The in vivo study showed that administration of sustained release tablets eliminated high serum peaks and prolonged the duration of an elevated serum level as compared to conventional tablets. The biovailability of the fluoride was lower after intake of sustained release and enterocoated tablets, and there was an increase in the interindividual variance of biovailability.

Adult↗

PubMed1985

In vivo and in vitro evaluation of magnesium-aluminum hydroxide antacid tablets and liquid.

The effect of magnesium-aluminum hydroxide antacid tablets or liquid on food-stimulated gastric acidity was evaluated in vivo in eight duodenal ulcer patients. Experiments were performed also in vitro. Although in vitro neutralizing capabilities of the two preparations were the same (28.3 +/- 0.1 mmol/liter), the duration of effect of tablets was longer in vivo. For example, at 3 3/4 hr after an eaten meal, mean hydrogen ion concentration with three tablets was 29.8 +/- 9.9 mmol/liter while with 15 ml liquid it was 59.6 +/- 10.3 mmol/liter (P less than 0.05). Additional studies were performed in vitro to explain the longer duration of effect of tablets compared with liquid in vivo. These experiments suggested that tablets reacted more slowly with acid than did liquid and that saliva, which was mixed with tablets during chewing, also contributed to the prolonged duration of effect.

Aluminum Hydroxide↗

PubMed1982

Studies on different dissolution models. IV. Erosion of tablets.

A comparative study of the action of erosion on non disintegrating theophylline tablets was performed in the three USP XX dissolution models, the rotating basket, the paddle and the modified disintegration apparatus, as well as in a new (sandwich) model. The results show erosion to be dependent on the mechanical strength of the tablets and to be promoted by the phenomenon of softening of the tablets during the process of dissolution. A considerable and moderate erosion was found for 'soft' tablets in the rotating basket and disintegration apparatus, respectively, whereas no or only slight erosion was observed in the paddle and sandwich models. The phenomenon of dissolution intensified erosion and erosion intensified dissolution is shown to affect the description of the release profiles. The dissolution profiles of the 'hard' tablets in the models preferred to be described by the square root equation, whereas the profiles of the 'soft' tablets in the case of erosion showed a tendency to a better fit with the cube root of mass versus time relation.

Kinetics↗

PubMedDate not supplied

Stable isotope methodology for studying the performance of metoprolol Oros tablets in comparison to conventional and slow release formulations.

Metoprolol Oros tablets were designed to deliver their drug content as a constant rate over a period of time longer than that currently recorded with slow-release dosage forms. The bioavailability of 7/95, 14/190 and 21/285 Oros tablets was compared to that of either 100 mg conventional or 200 mg slow-release Lopresor tablets in 3 two-period change over experiments. In each experiment, 6 healthy volunteers received intravenous deuterated metoprolol concomitantly with one of the Oros systems or with one of the other two formulations. The Oros tablets gave rise to lower and steady plasma levels of metoprolol over 24 h than the other formulations. Their mean absorption time was around 3 times longer than that of the slow-release tablets. The amount of the drug absorbed unchanged was linearly related to the dose. The influence of the gastrointestinal transit time on the performance of Oros tablet was limited. These studies demonstrated the value of the stable isotope methodology in bioavailability assessment for drugs presenting a high inter-subject variability in their plasma clearance such as metoprolol.

Absorption↗