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At least 73 records · Page 4Linked to original sources

PubMed2003

Comparison of the compression characteristics between new one-step dry-coated tablets (OSDRC) and dry-coated tablets (DC).

One-step dry-coated tablets (OSDRC) were prepared using materials which are generally used in pharmaceutical tablets. The radial tensile strength of OSDRC was measured for various compression pressures and core porosities before the final compression to compare with that of conventional dry-coated tablets (DC). Furthermore, stress relaxation in the compression process was investigated. Radial tensile strength and stress relaxation profiles of OSDRC were the same as those of conventional DC. X-ray computerized tomography (CT) of the tablets showed that the density distribution of both tablets was also the same. Thus, we concluded that OSDRC and conventional DC have the same compression characteristics and physical properties. The OSDRC-system was executed by the use of upper and lower punches, which had a double structure, a center punch, and an outer punch surrounding the center punch. The OSDRC process consists of three compressions to make the lower-outer layer (1st-outer layer), the core, and the whole tablet including the upper-outer and side-outer layers (2nd-outer layer). At first, the powder for the 1st-outer layer fills a space, which is made by the lower-center punch and lower-outer punch, and is pre-compressed by the upper-center punch. Then, while the upper-center punch pushes the pre-compressed 1st-outer layer, the lower-center punch is slid down. The upper-center punch is then pulled away to make a space, which is filled with the powder for the core. This is then pre-compressed by the upper-center punch. Finally, the lower-outer punch is slid downward and the powder for the 2nd-outer layer fills and surrounds the pre-compressed core/1st-outer layer completely. The core/1st-outer layer and the 2nd-outer layer complex is then compressed by the upper and lower punches in which the center punches are unified with the outer punches, respectively. This system can be assembled onto the turn table of a rotary tableting machine, and can make a dry-coated tablet in a single turn.

Ascorbic Acid↗

PubMed2000

Development of terfenadine-pseudoephedrine double-layer tablet dissolution-equivalent to core tablet.

The terfenadine-pseudoephedrine dosage form discussed here is the sustained-release core tablet composed of outer (fast-release) and inner (sustained-release) layers. To develop the double-layer tablet dissolution-equivalent to a core tablet, the fast-release and sustained-release layers were prepared using various disintegrants and polymers, respectively. The layer composed of terfenadine/pseudoephedrine/lactose/cornstarch/sodium bicarbonate/hydroxypropylcellulose (HPC)/sodium lauryl sulfate/microcrystalline cellulose (60/10/90/30/20/1/40/1/293 mg), which gave the fast disintegration time and high dissolved amounts of drugs, was selected as the fast-release layer. The dissolved amounts of pseudoephedrine from sustained-release layers increased more with a smaller ratio of ethylcellulose and hydroxypropylmethylcellulose (HPMC). Dissolution mechanism analysis showed the release of pseudoephedrine was proportional to the square root of time, indicating that drug might be released from the layers by Fickian diffusion. The layer composed of pseudoephedrine/ethylcellulose/HPMC (110/30/155 mg), which had similar dissolution amounts of pseudoephedrine as the inner layer of a core tablet, was selected as the sustained-release layer. Furthermore, the dissolved amounts of drugs from the core and double-layer tablets had deviations of less than 5% against the average dissolved amounts of drugs at each time. There was no significant difference between the dissolved amounts of drugs from these tablets at each time in pH 1.2, 4.0, and 6.8 (P > .05). Our results suggest that this double-layer tablet was a dissolution equivalent to the core tablet.

Chemistry, Pharmaceutical↗

PubMed2002

Roller compaction and tabletting of St. John's wort plant dry extract using a gap width and force controlled roller compactor. I. Granulation and tabletting of eight different extract batches.

The purpose of this study was to investigate the influence of roller compaction parameters on granule and tablet quality of a dry herbal extract from St. John's wort (Hypericum perforatum L.), which is widely used in the treatment of mild to moderate depressive disorders. Eight different extract batches were blended with 0.5, 2, and 5% of magnesium stearate and were compacted at different compaction forces using a gap width and force controlled roller compactor. The ribbon formed was milled into granules having mean particle sizes up to 700 microns. The roller compaction of the extracts decreased significantly the angle of repose from about 45 to 32 degrees and the Hausner ratio from about 1.2 to 1.1. Tabletting of granulated extract instead of extract powder effectively reduced not only dust and feeding problems during the tabletting process but also prevented capping. The incorporation of 2 and 5% of magnesium stearate into the roller compacted extract reduced significantly the sticking of the dry herbal extracts to the punch faces without affecting the crushing strength of the tablets. Tablets containing granulated extracts exhibited a 3-fold lower disintegration time of about 12 min compared to tablets containing extract powder. Dissolution studies revealed that hyperforin, hypericin, and rutin were more rapidly released from tablets containing granulated extract. Therefore, roller compaction leveled out the differences in technological properties between the eight dry herbal extracts and compression of granulated extract significantly improved tablet quality.

Compressive Strength↗

PubMed1990

Felodipine extended-release tablets once daily are equivalent to plain tablets twice daily in treating hypertension. Dutch Hospital Multicentre Group.

The efficacy of and tolerance to felodipine given as extended-release (ER) tablets once daily (o.d.) and the plain tablets twice daily (b.i.d.) were compared in this study. After a 4-week period on placebo and a beta-blocker, 102 patients who had a diastolic blood pressure (DBP) in the supine position greater than 95 mm Hg were randomized to treatment with felodipine ER tablets 10 mg o.d. (n = 50) or plain tablets 5 mg b.i.d. (n = 52). If the DBP was greater than 90 mm Hg after 2 weeks, the dose was doubled. The total treatment time on felodipine was 6 weeks. Blood pressure (BP) was measured 2 h after the dose and at the end of the dosing interval, i.e., 24 h after ER and 12 h after plain tablets. Both formulations reduced BP significantly (15/12 mm Hg in the ER and 13/11 mm Hg in the plain tablet group, at the end of the dosing interval). No differences in BP reduction were seen between the groups. The proportion of responders was 71% on ER and 65% on plain tablets 24 and 12 h, respectively, after dose intake, and greater than 90% in both groups, when measured 2 h after dose. Ankle swelling and flushing were the most frequently reported adverse events. Eight patients (three on ER) were withdrawn, most of them due to vasodilatory side effects. Felodipine ER once daily was as effective and tolerable as plain tablets b.i.d.

Adult↗

PubMed1986

Film-coated zinc sulphate tablets and the effect of humidity on tablet properties.

Preparation of film-coated zinc sulphate tablets and the effect of relative humidity and aging on the physical properties of these coated tablets were investigated in this study. Shellac; Eudragit E and L, hydroxypropyl methylcellulose (HPMC) and HPMC-Eudragit E mixture were used as film-forming materials. As zinc sulphate has efflorescent properties, the effect of humidity on the coated tablets was studied and physical stability tests were carried out. Coated tablets were kept in bottles and in open petri-dishes at different relative humidities (30, 55 and 85%) at room temperature over 12 weeks, and the weight loss, hardness, and disintegration times of these tablets were followed. Findings indicated that film-coated zinc sulphate tablets having good tablet quality can be prepared using the formulations (F-VI) HPMC-Eudragit E mixture and (F-III) Eudragit E as coating materials. Thus, the effect of relative humidity on tablet properties can be reduced.

Drug Stability↗

PubMed1979

[The effects of various factors on the in vitro velocity of drug release from repository tablets. Part 4: Isoniazid (Rimicid) respository tablets (author's transl)].

The authors investigated the release of isoniazid from repository tablets as related to form, processing technology, strength constant and storage for 5 years. On determining the diffusion coefficient (D), the initial dissolution rate (Vo) and the time required for the diffusion of the releasing medium to the middle of the tablet (t1/2), it was found that the difference in release rate between the flat and the biconvex tablets is small. Furthermore, it was stated that the three-layer tablets have very high D and Vo values and very low t1/2 values, for what reason they are unsuited for repository tablets of the composition under investigation. Moreover, it was found that an increase of the strength constant does not affect the D, t1/2 and Vo values, and that the release of isoniazid is retarded only in flat tablets with the highest strength constant. Storage exerts no effect on the drug release from these tablets. The industrial production of these tablets is under way.

Delayed-Action Preparations↗

PubMed1986

Comparison of a controlled-release tablet of salbutamol given twice daily with a standard tablet given four times daily in the management of chronic obstructive lung disease.

In a double-blind cross-over study 20 patients with reversible airways obstruction were treated either with conventional 4 mg tablets of salbutamol a.i.d., or 8 mg controlled release (CR) tablets of salbutamol b.d. Each treatment was given for 2 weeks. The morning PEFR was significantly higher with the CR tablets (p less than 0.05) but although the evening PEFR was also better the difference was not significant. Wheeze was significantly lower (p less than 0.05) and extra "rescue" inhalation of bronchodilators was required less often and on fewer occasions during treatment with the CR tablets. Comparison of the 12-h mean plasma salbutamol profile showed a peak and trough every 6 h with the standard tablets, and a flatter profile with a single, lower and delayed peak during the 12 h between CR tablets. Although the minimum and average plasma salbutamol levels were similar in the groups on the two preparations, the maximum plasma level was significantly lower and there was significantly less fluctuation on CR tablets (p less than 0.02). The CR and standard tablets had equivalent bio-availability.

Adult↗

PubMed1992

The efficacy and tolerability of controlled-release dihydrocodeine tablets and combination dextropropoxyphene/paracetamol tablets in patients with severe osteoarthritis of the hips.

A double-blind, parallel group study was undertaken in general practice to compare the efficacy of and tolerability to controlled-release (CR) dihydrocodeine tablets and combination dextropropoxyphene/paracetamol tablets in patients with severe osteoarthritis of the hip(s). Eighty-six patients were randomly allocated to receive either CR dihydrocodeine (60 mg) tablets (1 tablet twice daily to 2 tablets daily) or combination dextropropoxyphene (32.5 mg)/paracetamol (325 mg) tablets (2 tablets 3-times daily to 2 tablets 4-times daily) for a period of 2 weeks. Patients recorded in a diary card 4 times a day the severity of their pain and each morning whether or not they woke during the night due to pain in their hip(s). On entry to the study, after the first week's treatment and at the final visit another week later, the investigator assessed the patient's severity of pain on passive movement of the hip and also noted the severity of any volunteered symptoms or side-effects. After 2-weeks' treatment, pain on passive movement of the hip joint was statistically significantly less severe on CR dihydrocodeine than on dextropropoxyphene/paracetamol (p = 0.02). Nausea and vomiting were more pronounced in the dihydrocodeine than in the dextropropoxyphene/paracetamol group after the first week's treatment but by the end of the study there was no significant treatment difference in any of the volunteered side-effects. Patients on CR dihydrocodeine developed some constipation as expected and the dextropropoxyphene/paracetamol patients suffered from impaired concentration. More patients withdrew on CR dihydrocodeine than on dextropropoxyphene/paracetamol but these withdrawals tended to occur early in the trial just after initiating therapy. Tolerance in terms of withdrawals or side-effect profile did not appear to the dosage of each preparation administered. It is concluded that after 2-weeks' treatment CR dihydrocodeine provided superior analgesia to dextropropoxyphene/paracetamol with no difference in side-effects. Furthermore, CR dihydrocodeine has the advantage of twice rather than 3 or 4-times daily dosing.

Acetaminophen↗

PubMed1995

Deformation of the Stokes B2 rotary tablet press: quantitation and influence on tablet compaction.

Deformations that affect the vertical punch displacement of a Stokes B2 rotary tablet press were characterized with a cathetometer. The press deformation was found to be elastic for both the upper and lower compression roller assemblies. However, the upper and lower compression roller assemblies have different Hookian spring constants: 8.58 x 10(4) and 5.18 x 10(4) kN/m for the upper and lower assemblies, respectively. Using two-way analysis of variance, the Hookian spring constants were shown to be independent of compaction phases and lower punch penetration setting. To study the influence of press deformation on tablet compaction, the Hookian spring constants were factored into the caculation of the incremental work of compaction for dibasic calcium phosphate dihydrate and microcrystalline cellulose. As the peak compression pressure increases, the force-displacement work done on the tablet during the loading phase decreases relative to calculations that neglect press deformation. This decrease in force-displacement work was attributed to elastic press deformation, which absorbs energy during the loading phase and then releases this energy later in the compaction cycle, altering the punch-displacement profile. The rate at which the press stores and releases elastic energy depends in part upon the viscoelastic properties of the tablet. Based upon these results, the coupling between press elasticity and a tablet's viscoelastic properties should be accounted for when analyzing tablet compaction or trying to simulate the punch-displacement profile of a tablet press that deforms during compaction.

Chemistry, Pharmaceutical↗

PubMed1988

Safety and efficacy of once-daily Uniphyl tablets compared with twice-daily Theo-Dur tablets in elderly patients with chronic airflow obstruction.

Oxygen desaturation and subclinical coronary artery disease may predispose older patients with chronic airflow obstruction to cardiac arrhythmias, especially when high concentrations of theophylline are present in the blood. To assess the safety and efficacy of Uniphyl tablets, an oral theophylline preparation formulated for once-daily dosing, in elderly patients with chronic airflow obstruction, we conducted a randomized, three-phase, double-blind crossover study comparing evening dosing with Uniphyl tablets, Theo-Dur tablets administered twice daily, and placebo. The patients in the study were scheduled to receive each treatment for two weeks. Each day, symptoms, side effects, peak expiratory flow rates, and use of metered-dose inhalers were recorded. Near the end of each phase, serum theophylline concentrations were measured every two hours between 8:00 A.M. and 8:00 P.M. on two consecutive days. The patients underwent ambulatory Holter monitoring during the final 48 hours of each phase. Twelve patients completed the active-drug phases of the study, but seven of the 12 were removed from the placebo phase because of increasing symptom severity. The difference between the number of patients completing the active-drug and placebo phases was statistically significant (p less than 0.001). Treatment with Uniphyl tablets resulted in a significantly (p less than 0.05) greater increase in peak expiratory flow rate than Theo-Dur tablet therapy, and both active drugs increased peak expiratory flow rate more than placebo. Circadian variation in peak expiratory flow rate was seen during the placebo and Theo-Dur tablet phases but not during the Uniphyl tablet phase. Symptoms and side effects were similar during the two active-drug phases. Cardiac ectopy was observed in most of the patients, but it was not significantly greater during the theophylline phases than during the placebo phase. Furthermore, ectopic activity was not directly related to the times of maximal serum theophylline concentration.

Aged↗

PubMed2004

How do roll compaction/dry granulation affect the tableting behaviour of inorganic materials? Microhardness of ribbons and mercury porosimetry measurements of tablets.

The effect of roll compaction/dry granulation on the ribbon and tablet properties produced using different magnesium carbonates was evaluated. The ribbon microhardness and the pore size distribution of tablets were used as evaluation factors. Increasing the specific compaction force resulted in higher microhardness for ribbons prepared with all four magnesium carbonates accompanied with decreased part of fine. Consequently, the corresponding produced tablets displayed a lower tensile strength. A possible correlation between the particle shape, surface area and the resulting pore structure of tablets produced with the four different types of magnesium carbonate was observed. The tensile strength of tablets prepared using granules was lower than tensile strength of tablets produced using starting materials. The partial loss of compactibility resulted in a demand of low loads during roll compaction. However, the impact of changes in the material properties during the roll compaction depended greatly on the type of magnesium carbonate, the specific compaction force and the tableting pressure applied.

Chemistry, Pharmaceutical↗

PubMed2006

Raman spectroscopy of coated pharmaceutical tablets and physical models for multivariate calibration to tablet coating thickness.

Raman spectra of a set of coated pharmaceutical tablets were analyzed for the purpose of calibrating the spectra to tablet coating thickness. Acetaminophen tablets were coated with a hydroxypropylmethylcellulose/polyethylene glycol film coating whose thickness was varied from 0 to 6% weight gain. Coatings were also prepared with two concentrations of TiO2 at several film thicknesses. The resulting spectral data set was analyzed using several different multivariate calibration procedures. The procedures examined in this study included spectral correction followed by target factor analysis, spectral correction with baseline subtraction followed by principal component regression, and first derivative computation followed by principal component regression. The results demonstrate that target factor analysis is a viable method for calibration of Raman spectra to tablet coating thickness. Calibration based on derivative spectra resulted in linear correlation that was equal to that of the results of target factor analysis for coatings without TiO2. However, target factor analysis was found to be superior to other methods when TiO2 was present in the tablet coatings. The effect of sample fluorescence on each of these chemometric methods was also examined. It was found that when photobleaching of fluorescent impurities due to exposure to the Raman excitation source was controlled, the tablet coating thickness could be calibrated to the intensity of the fluorescence signal. The results also demonstrate that for the samples examined here, calibration by target factor analysis is insensitive to variation in fluorescent intensity when the tablet coating emission spectrum is included in the matrix of target vectors.

Acetaminophen↗

PubMed2001

An investigation of pulsatile release tablets with ethylcellulose and Eudragit L as film coating materials and cross-linked polyvinylpyrrolidone in the core tablets.

To develop new pulsatile release tablets, which can suppress drug release in stomach and release the drug rapidly after a predetermined lag time of about 3 h in intestine, the use of tablets with ethylcellulose/Eudragit L as a coating film and cross-linked polyvinylpyrrolidone in the core tablets was investigated. The release of diltiazem hydrochloride (DIL) as a model drug in the core tablets was investigated in vitro. The lag time (t10) was prolonged with an increase of the coating level, whereas the drug release rate was almost constant, irrespective of the coating level. The water-uptake study and electron microscope photographs suggested the mechanism of pulsatile release of drug. Pulsatile release tablets containing 60 mg DIL with 4.4 h of lag time (t10) in vitro were administrated to eight volunteers. The mean plasma concentration curves showed 4.9 h of lag time (tlag), 8.0 h of time to maximum concentration (tmax) and 3.1 h of time between tmax and tlag (t(psi)) in vivo. Relative bioavailability was 1.05 for pulsatile release tablets compared to conventional tablets.

Adult↗

PubMed2000

Development of disintegrating multiple-unit tablets on a high-speed rotary tablet press.

Enteric coated bisacodyl pellets were compressed into divisible disintegrating tablets on a high speed rotary tablet press and investigated for pellet damages. The degree of pellet damages was examined via the bisacodyl dissolution during the acid treatment of' the drug release test for enteric coated articles according to USP 23. The damages depended on the type of filler-binder used and settings of the tablet press. Avicel PH 101 proved to be the most suitable filler-binder, effecting homogeneous distribution of the pellets within the tablets, as could be shown by image analysis of coloured pellets. The speed of the tablet press had noo influence on the pellet damages using Avicel PH 101 as a filler-binder, however, tablets containing 70% (w/w) of coated pellets did not fulfil the requirements of USP 23, despite optimum elasticity and coating thickness of a new Eudragit FS 30 D coating. Reducing the proportion of pellets to 60% per tablet, less than 10% of bisacodyl were released within 2 h during acid treatment thus fulfilling the requirements of the USP 23.

Solubility↗

PubMed2004

Bioequivalence study of levothyroxine tablets compared to reference tablets and an oral solution.

The study was designed to evaluate the bioequivalence of three levothyroxine sodium (CAS 51-48-9) formulations, i.e. a test and a reference tablet and an oral solution. A bioequivalence study was carried out in 25 healthy volunteers, who were administered a single dose of 600 microg levothyroxine in the form of the test formulation (levothyroxine sodium tablets 200 microg; Eferox), the originator product, and an oral solution. The trial was performed in one study center according to an open, randomized, three-way cross-over design with wash-out periods of 35 days between administration. Blood samples were taken up to 48 h post dose, the plasma was separated and the concentrations of levothyroxine and triiodothyronine were determined by radioimmunoassay with I125 labeling method. The levothyroxine mean Cmax were 112.0+/-17.3 ng/ml, 113.4+/-18.5 ng/ ml and 111.3+/-15.1 ng/ml, while the mean AUC0-24 were 2263.7+/-332.8 ng x h/ ml, 2307.3+/-351.3 ng x h/ml and 2286.1+/-331.0 ng x h/ml for the test and reference tablets as well as for the oral solution, respectively. No significant differences were found of principal pharmacokinetic parameters between the studied formulations. The 90%-confidence interval for the primary target parameters, intra-individual ratios of AUC0-24 and Cmax of levothyroxine were within the acceptance ranges for bioequivalence trials, i.e. AUC0-24 0.954-1.016 and 0.966-1.011 as well as Cmax 0.948-1.027 and 0.968-1.032 for test tablets versus reference tablets and the oral solution, respectively. Similar results were observed for triiodothyronine. In the light of the present study it can be concluded that the levothyroxine test tablet is bioequivalent to the reference formulation in respect of extent and rate of absorption. The results of the present trial confirm the findings of a previous study, performed under steady-state conditions with Eferox tablets 100 microg in patients without thyroid function.

Adult↗

PubMed2000

Influence of tableting forces and lubricant concentration on the adhesion strength in complex layer tablets.

The strength of adhesion in complex two-layer tablets is assessed using statistical methods with respect to the applied tableting forces for the first layer and for applying the second layer on the first, as well as regarding the fraction of the lubricant. These results, obtained on a single-punch tablet press, are compared with the results for three-layer tablets produced on a rotary press at production scale. The strongest negative influence on adhesion strength was exerted by the amount of lubricant in the central layer. As expected, compression forces for central-layer tableting also had a negative effect, whereas the compression forces for complex layer tableting exerted a positive effect on layer adhesion. The validity of the derived model equation was proved by experiments: It was shown that the adhesion strength in complex layer tablets produced in production scale can be predicted from laboratory-scale experiments. This makes optimization of the formulation and parameter settings at an early stage of development possible.

Adhesiveness↗

PubMed2001

Fine-Particle ethylcellulose as a tablet binder in direct compression, immediate-release tablets.

Ethylcellullose has traditionally been used in tablets as a binder in an alcohol solution form. In the present study, fine-particle ethylcellulose (FPEC) was used as a binder to manufacture immediate-release tablets by the direct compression technique. The binding potential of FPEC is compared to that of commercially available coarse-particle ethylcellulose at the same viscosity grade and to that of hydrophilic binders. The compression force setting was kept constant for all batches. The concentration of the binder was varied from 5% to 25%. Acetaminophen was used as a model drug because capping is a problem frequently observed during high-speed compaction and further processing of acetaminophen tablets. In this study, there would be an increase in the contact area with FPEC and hence greater bond formation. This greater bond formation should be able to reduce the problem of capping in tablets containing highly elastic materials such as acetaminophen. Tablets were evaluated based on the following tests: weight variation, extent of capping, hardness, friability, disintegration, and dissolution. Based on the results of these tests, FPEC proved to be an effective binder for directly compressed acetaminophen tablets. The 10% and 15% formulations of FPEC passed all the tests and also produced the hardest tablets.

Acetaminophen↗

PubMed1987

A comparative bioavailability study of carbamazepine tablets and a chewable tablet formulation.

Differences in product formulations have been shown to affect the therapeutic response by altering the relative bioavailability and pharmacokinetics of a drug. The relative bioavailability and pharmacokinetics of carbamazepine tablets (CBZ) and a chewable tablet formulation were evaluated in 10 normal healthy subjects (five men and five women). The study utilized a randomized, crossover design with a 4-week washout period between doses. Blood samples were collected at 0, 1, 2, 3, 4, 6, 8, 10, 14, 24, 30, 36, and 48 h following a 200-mg dose. Plasma samples were assayed by fluorescence polarization immunoassay. Ke, Cmax, Tmax, area under the curve (AUC), and relative bioavailability were estimated using traditional pharmacokinetic methods and compared by paired t test. A statistically significant higher Cmax (3.81 +/- 81 vs. 4.64 +/- .80 mg/L) was observed with the chewable tablet formulation but was not thought to be clinically relevant. No significant differences between formulations for Ke (0.022 +/- 0.007 vs. 0.025 +/- 0.008 h-1 h), Tmax (7.49 +/- 2.69 vs. 6.04 +/- 2.7 h), AUC 48 h (119 +/- 22 vs. 133 +/- 13 mg/h/L), or AUCO--infinity ( 221 +/- 40 vs. 203 +/- 41 mg/h/L) were noted. Absorption was variable for both preparations. The relative bioavailability using the tablet as the standard formulation was (0.92 +/- 0.22). Transient, mild side effects were noted in three subjects with the chewable tablet alone, and one subject experienced side effects with both formulations. It was concluded that CBZ tablets and chewable tablets may be used interchangeably; however, considerable intra- and intersubject variability exists, and the need for patient monitoring is emphasized.

Adult↗