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PubMed1998

Pharmacokinetic evaluation in dogs of theophylline in a novel zero-order release core-in-cup tablet.

A new core-in-cup tablet that is manufactured from a novel adjustable punch, has been formulated and evaluated for its ability to release with subsequent absorption of theophylline via a zero-order rate of absorption. The core-in-cup tablets were compared with core only tablets and immediate release capsules. Pharmacokinetic parameters used to test the effectiveness of the formulations included, elimination rate, rate and kinetic order of absorption, relative availability as compared with an immediate release capsule of pure theophylline, and percentage area under the curve fluctuation (%AUCF) at steady state. The correlation coefficient, Akaike's information criterion (AIC) and the F-ratio probability were used to test the applicability of a zero-order, first-order, or square root of time model, for the rate of release of theophylline from the core-in-cup and core only tablets. The zero-order rate model was most applicable to the core-in-cup tablet, whereas the square root of time release model was most applicable to the core only tablet. The average %AUCF for the core-in-cup tablet was 9.26+/-3.15 while that for the core only tablet was 16.19+/-2.37 (p = 0.0545). The results of this study suggest that the core-in-cup tablet is a versatile zero-order release rate dosage form that are simple to produce.

Animals↗

PubMed2001

Influence of crystal shape on the tableting performance of L-lysine monohydrochloride dihydrate.

The purpose of this study is to understand the influence of crystal shape on the tableting performance of L-lysine monohydrochloride (LMH) dihydrate, using the method of data analysis developed by Joiris E et al. 1998. Pharm Res 15:1122-1130. Phase-pure crystals of LMH dihydrate, prism-shaped (S) and plate-shaped (T), were prepared by adjusting the composition of the crystallization solvent. At the same compaction pressure, T always gives stronger tablets than S, (i.e.; the tabletability of T is greater). The porosity of tablets from T crystals is always greater than that of S crystals when compressed at the same pressure, (i.e.; the compressibility of T is lower). The tensile strength of T tablets, at the same porosity, is greater than that of S tablets, (i.e.; the compactibility of T is greater). Therefore, the greater tabletability of T is a result of its better compactibility that overcomes the negative effects by its lower compressibility. The greater compactibility of T is related to favorable orientation of the slip planes in the tablet, corresponding to greater plasticity under load. The yield strengths of T and S crystals are essentially the same (20 MPa). Therefore, the crystal shape influences the tableting performance but does not, in principle, affect the yield strength of LMH dihydrate.

Compressive Strength↗

PubMedDate not supplied

A steady-state evaluation of the effects of propantheline bromide and cholestyramine on the bioavailability of digoxin when administered as tablets or capsules.

Drug interactions can profoundly alter the absorption of digoxin in tablet form. This study evaluated whether digoxin solution in capsules, a new dosage form with 90% to 100% bioavailability, would reduce such alterations, specifically those caused by cholestyramine and propantheline bromide. The investigation used a six-treatment, steady-state, balanced, incomplete block design with 18 healthy adults studied for four continuous two-week treatment periods. Treatments were either two 0.25 mg digoxin tablets or two 0.20 mg digoxin capsules administered alone, with propantheline, 15 mg qid, or with cholestyramine, 8 g qd. Bioavailability was determined from steady-state, 24-hour area under the serum concentration-time curve (AUC, ng X h/mL) and from 0- and 24-hour trough serum digoxin concentrations (ng/mL). The AUCs for tablets alone, with cholestyramine, and with propantheline were 32.8 +/- 13.3 (+/- SD), 22.4 +/- 12.1, and 40.6 +/- 13.9, respectively, while corresponding values for capsules were 31.7 +/- 9.3, 24.7 +/- 7.9, and 35.9 +/- 12.8. The trough concentrations for tablets alone, with cholestyramine, and with propantheline were 0.88 +/- 0.47, 0.61 +/- 0.38, and 1.09 +/- 0.35, respectively; trough concentrations for capsules were 0.77 +/- 0.28, 0.74 +/- 0.28, and 0.96 +/- 0.48, respectively. The only significant differences in AUC were seen when comparing tablets alone versus tablets with cholestyramine (P less than .0005) and tablets with propantheline (P less than .01). A significant finding was also observed when comparing trough concentrations for tablets alone versus tablets with cholestyramine (P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1975

Stability study of nitroglycerin sublingual tablets.

Nitroglycerin sublingual tablets were studied over a 1-year period to determine tablet stability in terms of loss of strength, uniformity of tablets, and degradation of the drug itself. Tablets from six different firms were analyzed by a semiautomated procedure. The samples included two molded tablets and four compressed tablets, ranging in age at the time of initial assay from 40 days to over 1 year. The results indicated that there is a loss of strength of nitroglycerin tablets and that refrigeration slows down this loss. The study also indicated that these tablets were stable during the year of testing in terms of tablet uniformity and degradation of nitroglycerin.

Analysis of Variance↗

PubMed1976

Stabilized compressed nitroglycerin tablets.

A stabilized compressed nitroglycerin tablet, containing microocrystalline cellulose NF and providone NF as stabilizing agents, was formulated. Bioavailability and physical tests were conducted on the compressed tablet and two leading brands of molded tablets. There was no difference in the mean pulse rate between a molded tablet formulation and the compressed tablet in a crossover study using 10 human volunteers and three tablet strengths, 0.3, 0.4, and 0.6 mg. The compressed tablet was most uniform when tested according to the USP method for weight variation and content uniformity. Various tests for nitroglycerin loss due to volatility, i.e., open dish test, thermogravimetric analysis, and simulated in-use test, all indicated that the stabilized compressed tablet was substantially more stable than partially stabilized or unstabilized molded tablets.

Adult↗

PubMed1977

Bioavailability of sulfadiazine in rabbits using tablets prepared by direct compression and fluidized-bed granulation.

Experimental sulfadiazine tablets prepared by direct compression, using a commercially available direct compression tablet mass, were compared with experimental sulfadiazine tablets prepared by fluidized-bed granulation and commercially available sulfadiazine tablets USP. The values for friability and the time required to release 10 and 50% of the direct compression tablets were between those of the fluidized-bed tablets and the commercial product. With the commercial tablet as a standard, the extent of bioavailability was determined in rabbits; it was slightly higher for both the direct compression and fluidized-bed tablets. A statistically significant difference was found between the direct compression tablets and the standard with respect to the extent of bioavailability and the time of the peak.

Animals↗

PubMed1980

New instrumentation for determining flexure breaking strength of capsule-shaped tablets.

New instrumentation to measure the flexure breaking strength of capsule-shaped tablets was developed. It consisted of a mechanical linkage to apply the breaking load at a uniform rate and a strain-gauge instrumented cantilever beam to convert the load to a proportional millivolt response on a recorder. A recorder tracing was obtained of increasing load with time, with a break in the tracing denoting the tablet's flexure breaking strength. Measurements were made for different tablet hardnesses, and a plot of tablet hardness versus flexure breaking strength yielded a profile of the mechanical strength of the tablet. The instrumentation was shown to have application for determining the effects of tablet thicknesses, tablet ingredients, tablet sizes, cup depths, and bisect dimensions on tablet strength.

Capsules↗

PubMed1983

Effect of intergranular versus intragranular cornstarch on tablet friability and in vitro dissolution.

The effect of blending dry cornstarch versus wet granulation with the drug and other excipients on friability and in vitro dissolution of a ticlopidine hydrochloride tablet formulation was studied. The friability of the tablets was reduced by wet granulating cornstarch with the drug and other excipients compared with the dry blending. The dissolution rate and the tablet-to-tablet variability was improved by incorporating cornstarch in the wet-granulation stage. The lactose placebo tablets, which were wet granulated with either a binder solution or without a binder, also showed reduced tablet friability due to the incorporation of cornstarch in the wet-granulation step. Examination of the tablet cross sections under the scanning electron microscope indicated clumping of starch grains when starch was blended in the dry form. Starch grains were well embedded in the other materials of the tablet and not readily visible when starch was wet granulated with the other excipients. This results in better bonding, fewer weak points, and better homogeneity of the starch disintegrator within the tablet, which accounts for better friability and improved dissolution.

Hardness↗

PubMed1984

Neutron activation of iron tablets to evaluate the effects of glycine on iron absorption.

Neutron bombardment (neutron flux, 3 X 10(12) neutrons/cm2/s) of prepared iron tablets containing glycine-iron or iron alone was performed to prepare radioactive tablets to assess the effects of glycine on iron absorption from tableted formulations. No interfering isotopes of sufficient quantity were generated during neutron activation of the iron tablets. Cobalt-60 was the major trace mineral detected and accounted for only 1.3% of the total activity. There may have been trace amounts of zinc-65 or chromium-51 present, but they were not detectable above background radioactivity in the final tablet produced. Iron-59 represented greater than 98% of the radioactivity present in the tablets used in the study. Glycine-containing iron tablets produced dramatically higher amounts of iron in blood and tissues of rabbits (p less than 0.05) than did the same tablet formulations without glycine. The area under the iron blood concentration-time curve over 4 h increased by 67% with glycine added to the formulation over control iron tablets. Iron concentrations in tissues 4 h after iron administration was in the order of blood greater than liver greater than heart greater than kidney greater than muscle.

Animals↗

PubMed1990

Nondestructive near-infrared analysis of intact tablets for determination of degradation products.

Near-infrared spectrometry was used in this study to examine intact aspirin tablets in order to demonstrate the usefulness of the technique as a nondestructive method of quality control. Unique sampling optics were used to simultaneously illuminate the entire surface of the tablets, including the top, bottom, and side. Changes in individual tablet spectra were correlated to (a) the time that the tablets spent in a hydrator, (b) the mass of water absorbed by the tablets, and (c) the mass of salicylic acid formed by base-catalyzed hydrolysis of acetylsalicylic acid. A prediction equation for each of these three parameters was constructed using near-infrared spectral reflectance values obtained from intact tablets. Prediction errors were low for (a) the time that tablets spent in the hydrator (+/- 19 h over a period of 168 h), (b) the mass of water absorbed (+/- 0.04% of tablet mass), and (c) the mass of salicylic acid formed (+/- 0.04% of tablet mass).

Aspirin↗

PubMed1995

1H-NMR microscopy of tablets.

A 1H-nuclear magnetic resonance (NMR) microscopy method was utilized for the first time to determine the porosity distribution of physically intact tablets. The main advantage of this newly developed method was that porosity cross sections through whole tablets or specific locations could be obtained without mechanically destroying the tested tablet. This was achieved by filling tablet cavities with silicone oil under vacuum. The amount of silicone oil locally within the tablet was then determined by 1H-NMR microscopy, revealing the inverse inner structure. To reduce the measuring time, a paramagnetic gadolinium complex was added to the silicone oil. The cross sectional signals produced by 1H-NMR microscopy through the tablet were transformed into a color image by a specially designed computer graphic program. To improve the signal-noise ratio an algorithm of 3D-filtering was introduced. The maximal spatial resolution achieved with this method was about 95 microns for a cube's edge length corresponding to some 380,000 positions in a 9-mm-diameter compression-coated tablet. Uneven porosity distributions within tablets, cracks, or cavities could be visualized with this newly developed method. Different compaction mechanisms were observed with plastic- or brittle-type tablets. The different states of densification during compaction of powders could be detected. The integrity of compression coatings was determined to be dependent on the pressure load and the location of the core within the coat.

Magnetic Resonance Imaging↗

PubMedDate not supplied

Relative bioavailability of different oral sustained release oxprenolol tablets.

The bioequivalence of oral dosage forms of oxprenolol was assessed in a triple crossover study on two groups of 12 volunteers each. Single 160 mg doses of oxprenolol hydrochloride were given after an overnight fast of either oxprenolol sustained-release tablets in a megaloporous system, a hydrophil matrix and Slow-Trasicor (Ciba-Geigy) in the first group, or floating slow-release tablets administered with food or in absence of food, and rapid release Oxprenolol (Terapia, Cluj-Napoca) tablets, in the second group. Serum oxprenolol concentrations were measured by a gas chromatographic method. Pharmacokinetic parameters which describe bioavailability and general kinetic behavior of the drug were calculated from individual serum profiles. They were subjected to statistical analysis (paired Student's t test, p < 0.05). The customary bioequivalence criterion was used: 0.8 < parameter ratio(tested/standard) < 1.2. Megaloporous tablets showed bioequivalence with the reference sustained release product Slow-Trasicor. Hydrophil tablets showed moderate sustained-release characteristics. Floating tablets showed significantly greater oxprenolol absorption when taken with food and were non-bioequivalent with floating tablets without food, as well as with the reference rapid release tablets, of oxprenolol. However, fasting tablets were bioequivalent to the Slow-Trasicor product, when taken with food.

Administration, Oral↗

PubMedDate not supplied

Pharmacokinetics and bioavailability of acyclovir sustained-release tablets in dogs.

The pharmacokinetics and bioavailability of acyclovir sustained-release tablets in dogs were investigated. Blood concentrations of acyclovir were determined by RP-HPLC after a single oral dose of two kinds of acyclovir tablets given separately to 6 beagle dogs. The main pharmacokinetics parameters of the acyclovir sustained-release tablet were as follows: T1/2, Tmax and Cmax were 4.10 +/- 0.20 h, 4.05 +/- 0.54 h and 6.90 +/- 0.68 [microg x ml(-1), respectively. MRT was 9.02 +/- 0.44 h. Using acyclovir standard tablet as control, relative bioavailability of the acyclovir sustained-release tablet was 152.2 +/- 49.90%. According to the two-tailed t-test, there was a distinct difference in the data for Tmax, Cmax and AUC between acyclovir sustained-release tablets and acyclovir standard tablets, and the absorbability of acyclovir sustained-release tablets was much better than that of the acyclovir standard tablets.

Acyclovir↗

PubMed2005

A novel in vitro and numerical analysis of shear-induced drug release from extended-release tablets in the fed stomach.

PURPOSE: To design an in vitro apparatus that could simulate the in vivo range of surface shear stresses relevant for the human stomach under fed conditions. METHODS: Computer simulations were combined with in vitro experiments to quantify tablet erosion rate vs. surface shear stress. From two separate computer models, of tablets in the fed stomach and of tablets in vitro, we first estimated the intragastric range of surface stress and Reynolds number (Re), and then designed a dissolution apparatus and parameter space to replicate the in vivo conditions. The in vitro tablet erosion was determined by a new rotating beaker apparatus that provided predictable surface shear on tablets. Tablet mass erosion rates were measured for two different extended-release tablets at a range of in vivo relevant surface shear stresses obtained by varying viscosity of test media and rotation rate of the beaker. RESULTS: Mass erosion rate and surface shear were found to be highly correlated. Erosion rate increased with surface shear more rapidly at "low" stresses (<35 dyne/cm2) independent of tablet material. At higher surface stress, erosion was strongly material dependent. CONCLUSIONS: Shear force effects on drug release from matrix tablets relevant for fed state are for the first time possible to predict by in vitro dissolution testing.

Algorithms↗

PubMed2004

Relative bioavailability and safety profile of gefitinib administered as a tablet or as a dispersion preparation via drink or nasogastric tube: results of a randomized, open-label, three-period crossover study in healthy volunteers.

BACKGROUND: Many patients with head and neck cancer have difficulty swallowing tablet formulations of medications, and use of dispersion preparations may be advantageous. OBJECTIVE: The aim of the present study was to determine the relative bioavailability and safety profile of a single dose of gefitinib, an orally active inhibitor of epidermal growth factor receptor tyrosine kinase, when administered as a whole 250-mg tablet or as a dispersion preparation via drink or nasogastric tube in healthy male volunteers. METHODS: This was a Phase 1, randomized, open-label, 3-period crossover study. Plasma samples obtained before dosing to 240 hours after dosing were analyzed for gefitinib using reverse-phase high-performance liquid chromatography with tandem mass-spectrometric detection. The pharmacokinetic parameters of interest included AUC, C(max), and the relative bioavailability of the dispersion via drink or nasogastric tube compared with the standard tablet. RESULTS: Eighteen healthy white male volunteers were enrolled. They had a mean age of 43 years (range, 21-59 years), mean body weight of 85.1 kg (range, 60-101 kg), and mean height of 180.3 cm (range, 171-187 cm). The geometric mean AUC was 2219 ng.h/mL for a single 250-mg dose of gefitinib administered as a whole tablet, 2233 ng.h/mL for the dispersion preparation administered by drink, and 2007 ng.h/mL for the dispersion preparation administered by nasogastric tube. The corresponding values for the geometric mean C(max) were 95.2, 96.3, and 89.9 ng/mL. The gefitinib dispersion preparation administered by drink had a mean bioavailability of 103.8% relative to the whole tablet; the dispersion preparation administered by nasogastric tube had a mean bioavailability of 99.1% relative to the whole tablet. For the drink-tablet and nasogastric tube-tablet comparisons, the estimate-of-treatment ratios for the AUC were a respective 1.006 and 0.928; for the C(max), they were 1.012 and 0.964. There appeared to be no clinically significant differences in absorption or elimination between the preparations. Three volunteers experienced adverse events (AEs) that were considered possibly related to gefitinib (pruritus and dry skin), and 6 volunteers experienced procedure-related AEs (cannula-site reaction and rhinorrhea); these AEs were mild or moderate. No serious AEs were recorded, and no AEs led to withdrawal of any volunteer. CONCLUSIONS: Administration of a 250-mg dose of gefitinib as a dispersion preparation by drink or nasogastric tube achieved a systemic exposure to gefitinib that was consistent with that achieved when gefitinib was administered as a whole tablet. There was no evidence of tolerability problems associated with the routes of administration studied in these healthy volunteers.

Administration, Oral↗

PubMed2003

Evaluation of the compression characteristics and physical properties of the newly invented one-step dry-coated tablets.

This study was conducted in order to clarify the compression characteristics, and to confirm the superiority of the physical properties, of the newly invented One-Step DRy-Coated tablets (OSDRC). We compared both the compression characteristics and the physical properties of OSDRC with those of physical-mixture tablets (PM) that were prepared with the same ingredients, quantity, and compression pressures. We selected potassium chloride (KCl) and acetaminophen (AAP) as the model drugs, since the former is known for its appropriate compression characteristics and the latter for its brittleness. The advantage of OSDRC is that they are capable of maintaining any kind of drug in their core, because the core is tightly surrounded by the outer layer, even when the drugs in the core have poor compression characteristics, which causes difficulties in forming a solid core tablet using conventional dry-coated tablet methods. The radial tensile strength of OSDRC was the same as, or superior to, that of PM containing of AAP. The results were in accordance with the compression process analysis performed according to Kawakita's equation. The friability of OSDRC was also superior to that of PM. These preferable characteristics were attributable to the high intensity of the OSDRC outer layer surface in comparison to that of PM. It was difficult to clarify the difference between OSDRC and PM in their physical properties when KCl was applied, since the tabletability of the whole tablet was high due to KCl's physical properties. The OSDRC containing AAP in their cores showed a controlled release pattern, though no other materials that have been known to influence drug release was present. It was considered that this controlled release pattern was caused by a reduced AAP particle surface area due to compression. It was confirmed with these experiments that the compression characteristics and the physical properties of AAP-OSDRC were superior to those of PM. These results indicated that it is possible to produce tablets that have materials with poor compression characteristics in the core portion, and high tabletability materials for the outer layers. In other words, it is possible to produce capsule-like tablets using the OSDRC compression method.

Acetaminophen↗

PubMed2005

Preparation of amoxicillin intragastric buoyant sustained-release tablets and the dissolution characteristics.

An intragastric buoyant sustained-release tablet (IGB-T) containing 100 mg of amoxicillin (AMX) was prepared to eradicate gastric Helicobacter pylori. A tablet prepared by compressing the mixture of hydroxypropylcellulose-H (HPC-H), citric acid (17.2 mg), sodium hydrogen carbonate (22.8 mg) and AMX was employed as the basic system for preparing IGB-T. The weight and diameter of the tablets were designed to be about 300 mg and 10 mm, respectively. IGB-T containing 5 mg of AMX and HPC-H (255 mg) was buoyant and showed a sustained-release pattern in water. However, when AMX was increased and HPC-H decreased to maintain the tablet weight (300 mg), there was no apparent sustained-release pattern. To prepare IGB-T containing 50 mg of AMX, the surface of the tablet was coated with HPC-H after a tablet was prepared from the mixture of AMX (50 mg), HPC-H (210 mg), citric acid (17.2 mg), and sodium hydrogen carbonate (22.8 mg). This tablet (IGB-T50-Coating) was buoyant and showed a sustained-release pattern in water. However, to complete IGB-T with 100 mg of AMX, it was necessary not only to coat the surface of the tablet but also to use granulated AMX with a particle size of 300-500 microm (IGB-T100-Coating-300-500G). IGB-T100-Coating-300-500G was confirmed to be buoyant for 24 h while maintaining a tablet shape and showed a sustained-release pattern in water and buffer solutions of pH 1.2 and 6.8.

Amoxicillin↗

PubMed2003

Pharmacokinetic comparison of fast-disintegrating and conventional tablet formulations of risperidone in healthy volunteers.

BACKGROUND: Difficulties with and resistance to tablet-taking are common in all patient groups and can exacerbate compliance problems and undermine treatment efficacy. In recent years, rapidly dissolving oral drug formulations have been developed to overcome problems related to swallowing difficulties. OBJECTIVE: The goal of this study was to evaluate the bioequivalence of a fast-disintegrating oral tablet of risperidone and the conventional oral tablet. METHODS: This was a randomized, open-label, 2-way crossover trial in which healthy volunteers received two 0.5-mg tablets of a fast-disintegrating oral risperidone formulation and two 0.5-mg tablets of conventional oral risperidone, each in a single administration. Blood samples for pharmacokinetic analysis of the active moiety (risperidone + 9-hydroxy-risperidone), risperidone, and its active metabolite 9-hydroxy-risperidone were obtained during a 96-hour period after dosing. Safety assessments included monitoring of adverse events, hematology and biochemistry tests of the sampled blood, urinalysis, blood pressure measurements, and electrocardiography. RESULTS: The bioequivalence assessment was based on pharmacokinetic and statistical analysis of data from 37 subjects who completed both treatment periods. The plasma concentration-time profiles of the active moiety, risperidone, and 9-hydroxy-risperidone were similar after intake of the 2 formulations. The fast-disintegrating tablet and the conventional tablet showed bioequivalence with respect to the active moiety, risperidone, and 9-hydroxy-risperidone. The 90% CIs for the mean treatment ratios of the log-transformed peak plasma concentration, area under the plasma concentration-time curve (AUC) to the last quantifiable time point, and AUC extrapolated to infinity were all within the predefined equivalence range from 80% to 125%. Twenty-eight of 50 (56%) subjects originally randomized reported adverse events, with a similar incidence for both treatments. All adverse events were mild, with somnolence and headache being the most frequently reported. No clinically relevant changes were observed in physical, biochemical, hematologic, or urinalysis variables during the study. CONCLUSION: In this study in healthy subjects, a single administration of two 0.5-mg fast-disintegrating risperidone tablets was bioequivalent to a single administration of two 0.5-mg conventional risperidone tablets.

Adult↗