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Three-layer guar gum matrix tablet formulations for oral controlled delivery of highly soluble trimetazidine dihydrochloride.

The present study is carried out to design oral controlled drug delivery systems for highly water-soluble drugs using guar gum as a carrier in the form of three-layer matrix tablets. Trimetazidine dihydrochloride was chosen as a model drug because of its high water solubility. Matrix tablet granules containing 30% (M1), 40% (M2) or 50% (M3) of guar gum were prepared by the wet granulation technique using starch paste as a binder. Three-layer matrix tablets of trimetazidine dihydrochloride were prepared by compressing on either side of guar gum matrix tablet granules of trimetazidine dihydrochloride M1, M2 or M3 with 200 mg of guar gum granules containing either 65% of guar gum (T1M1, T1M2 or T1M3), 75% of guar gum (T2M1, T2M2 or T2M3) or 85% of guar gum (T3M1, T3M2 or T3M3) as release retardant layers. The three-layer matrix tablets were evaluated for hardness, thickness, drug content uniformity, and were subjected to in vitro drug release studies. The amount of trimetazidine dihydrochloride released from the matrix and three-layer matrix tablets at different time intervals was estimated using a HPLC method. The three-layer guar gum matrix tablet (T3M3) provided the required release rate on par with the theoretical release rate for guar gum formulations meant for twice daily administration. The three-layer guar gum matrix tablet (T3M3) showed no change either in physical appearance, drug content or in dissolution pattern after storage at 40 degrees C/RH 75% for 6 months. The DSC study did not show any possibility of interaction between trimetazidine dihydrochloride and guar gum/other formulation excipients used in the study. The results indicated that guar gum, in the form of three-layer matrix tablets, is a potential carrier in the design of oral controlled drug delivery systems for highly water-soluble drugs such as trimetazidine dihydrochloride.

Administration, Oral↗

Correlation of characteristics of gel extrusion module (GEM) tablet formulation and drug dissolution rate.

The purpose of the study was to characterize the swelling properties of controlled release tablet formulations with compositional and processing differences. A correlation was also established between the drug dissolution rate from the controlled release gel extrusion module (GEM) tablet and the swelling properties of the core tablet. The GEM tablet consisted of a core tablet of water swellable Carbopol polymer, a neutralizing agent, drug, and excipients. The tablet was subsequently coated with a rigid, water impermeable membrane. A number of holes were then drilled by laser through the impermeable membrane. Dynamic mechanical analysis (DMA), Perkin Elmer DMA7, was used to characterize the swelling properties. During the swelling measurements, the measuring probe and sample were completely submerged in the surrounding medium. The results showed that the formulation containing potassium phosphate dibasic as a neutralizing agent had the highest swelling rate. Correspondingly, this formulation had the highest drug dissolution rate over the same time period. The processing difference included wet granulation and dry roller compaction. The compositional differences included different neutralizing agents, binders or Carbopol polymers. The results showed a linear relationship (r(2)=0.954) between the swelling rates of the core tablets and the drug dissolution rates of GEM tablets. No correlation was found between the drug dissolution rates and either the maximum extent of tablet swelling or the time needed to reach the maximum extent of swelling. The results demonstrated that DMA could be used to support both formulation and process development to determine the effects of different compositions and manufacturing processes on drug dissolution rates for swelling controlled release devices.

Chemistry, Pharmaceutical↗

Utilization of poly(DL-lactide-co-glycolide) nanoparticles for preparation of mini-depot tablets by direct compression.

PURPOSE: The objectives of this study were to prepare the long-acting matrix tablets by direct compression of the mixture of drug and poly(DL-lactide-co-glycolide) (PLGA) nanoparticles and to clarify the effects of such factors as polymer species, mixing ratio of nanoparticles with different molecular weights, and the tablet weight on the drug release and to discuss the mechanism of drug release from matrix tablets. In addition, mini-matrix tablets were prepared to investigate the possibility of application as an implantable dosage form. METHODS: PLGA nanoparticles were prepared by the modified spontaneous emulsion solvent diffusion method. The matrix tablets were prepared by direct compression of mixtures of drug and nanoparticles, and then the release properties, swelling properties and changes in molecular weight of PLGA during the release test were evaluated. RESULTS: The drug showed the biphasic release patterns from all matrix tablets; i.e. a portion of the drug was released rapidly (the initial release phase), the release stopped for a long period (the lag time), and then the residual drug was released (the second release phase). Matrix tablets with various biphasic release patterns could be prepared by altering the molecular weight or copolymer ratio of PLGA. The addition of nanoparticles of low molecular weight PLGA to those of high molecular weight reduced the release rate at the initial release phase, but that at the second release phase was almost entirely unaffected by mixing ratio. Also, the release patterns could be changed by altering the tablet weight and size, but the amounts released per unit of surface area were the same. Hydration analysis suggested that the initial release rates were correlated well with the swelling properties of tablets. CONCLUSION: This system had advantages in terms of simplicity in design and predictability of drug release rate and may be useful as an implantable dosage form.

Delayed-Action Preparations↗

Drug release from and mechanical properties of press-coated tablets with hydroxypropylmethylcellulose acetate succinate and plasticizers in the outer shell.

Dissolution profiles of diltiazem hydrochloride (DIL) contained in core tablets from press-coated (PC) tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) and plasticizers-adsorbent in the outer shell were investigated. Although, on the addition of triethyl citrate (TEC), triacetin (TA), and acetyltriethy citrate (ATEC) as plasticizers, DIL release was suppressed completely in first fluid (pH 1.2) for 10 h, it was not suppressed in HPMCAS on the addition of dibutyl sebacate (DBS) and acetylated monoglyceride. On the other hand, DIL in second fluid (pH 6.8) was released rapidly after a lag time in all the PC tablets. Water-soluble plasticizers such as TEC, TA, and ATEC showed greater compatibility to HPMCAS, and the results were consistent with suppression of DIL release in first fluid. Furthermore, as to PC tablets with HPMCAS and TEC-adsorbent, the DIL release in second fluid did not change after pretreatment in first fluid by the paddle-beads methods. To evaluate the resistance of the outer shell against such a mechanical impact, tablets with HPMCAS, HPMCAS and TEC- or DBS-adsorbent (H, HT, or HD tablets, respectively) were prepared. In compressive load-strain curves after immersion in first fluid, wet crushing strength was lower in the order of HT > H > HD tablets. Also, the curves of HT tablets at 3 and 21 h after immersion were quite different from those of other tablets, and it was hard to find crushing points. These results suggested that the resistance of the outer shell was due to plastic deformation properties involving some interaction between HPMCAS and TEC.

Cardiovascular Agents↗

Investigations into the stabilisation of drugs by sugar glasses: I. Tablets prepared from stabilised alkaline phosphatase.

The aim of this study was to investigate the formulation of sugar glass stabilised alkaline phosphatase from bovine intestine (BIAP) into tablets. Two major subjects of tablet formulation were investigated. First, the compaction behaviour of the inulin sugar glass was investigated. Secondly, the effect of the compaction process on the physical stability of sugar glass stabilised BIAP was investigated, comparing inulin and trehalose glass. The tabletting properties of freeze-dried inulin without BIAP were studied first. Freeze-dried inulin conditioned at either 20 degrees C/0% relative humidity (RH) or 20 degrees C/45% RH was compacted at various pressures. As expected, the yield pressure of the material conditioned at 0% RH was higher (68 MPa) than after conditioning at 45% RH (39 MPa). Tablets made of the material stored at 0% RH showed severe capping tendency, especially at high compaction pressures. In contrast, material conditioned at 45% RH gave tablets without any capping tendency and a friability of less than 1%. Sugar glasses of BIAP and either inulin or trehalose were prepared by freeze-drying (BIAP/sugar 1/19 (w/w)). The material was subsequently compacted. Tablets and powders were stored at 60 degrees C/0% RH. The activity of the incorporated BIAP was measured at various time intervals. It was found that inulin was by far superior to trehalose as stabiliser of BIAP in tablets. The poor stabilising capacities of trehalose after compaction are explained by crystallisation of trehalose induced by the compaction process and moisture in the material. The results clearly show that inulin is an excellent stabiliser for BIAP. The tabletting properties are adequate, showing sufficient tablet strengths and low friability. Furthermore, the good (physical) stability of inulin glass with respect to exposure to high relative humidities makes it practical to work with.

Alkaline Phosphatase↗

Fast dispersible ibuprofen tablets.

Fast dispersible tablets disintegrate either rapidly in water, to form a stabilized suspension, or disperse instantaneously in the mouth to be swallowed without the aid of water. A direct compression method was used to prepare these two types of tablets containing coated ibuprofen as a high dosed model drug. The properties of the water dispersible tablet, such as porosity, hardness, disintegration time and increase in viscosity after dispersion, were investigated. The selected tablet formulation, containing 26% galactomannan and 5% crospovidone, disintegrates before the galactomannan starts to swell. These tablets disperse in water within 40 s and show a crushing strength of 95 N. To develop an orodispersible tablet, a rotatable central composite design was applied to predict the effects of the quantitative factors mannitol and crospovidone as well as compression force on the characteristics of the tablet. Special emphasis was paid to the development of a wetting test, replacing the normal disintegration method. An optimum tablet formulation, containing 34% mannitol and 13% crospovidone, provides a short wetting time of 17 s and a sufficient crushing strength of 40 N. In conclusion, fast dispersible tablets with acceptable hardness and desirable taste could be prepared within the optimum region.

Administration, Oral↗

Near-infrared FT-Raman spectroscopy as a rapid analytical tool for the determination of diltiazem hydrochloride in tablets.

This study was performed to develop a fast and reliable analytical method for the quantitative determination of diltiazem hydrochloride in tablets. HPLC is currently the preferred method, but is time consuming due to extensive sample preparation. FT-Raman spectroscopy was used to quantitatively analyse diltiazem hydrochloride in commercially available tablets (Tildiem) and in experimental tablets prepared at lab-scale. The percentage of diltiazem hydrochloride in each tablet was determined by calculating-after vector normalisation-the total peak area of the spectral band between 1625 and 1560 cm(-1). No spectral interference from tablet excipients was seen at this spectral band. After FT-Raman spectroscopy the same samples were analyzed based on the HPLC method described in the USP XXIV. The drug dosage per tablet obtained from the vibrational spectroscopy method correlated well with the results obtained using HPLC analysis for both the commercial tablets (HPLC: 63.57+/-0.13 mg; Raman: 63.28+/-0.26 mg (n=50)) and the experimental tablets (HPLC: 181.02+/-0.25 mg; Raman: 181.22+/-0.35 mg (n=50)). FT-Raman is a reliable alternative for the HPLC method to quantify the amount of diltiazem hydrochloride in tablets. The spectroscopic method is faster because it eliminates sample pre-treatment. Furthermore the FT-Raman method has an additional advantage of not requiring solvents.

Chromatography, High Pressure Liquid↗

Mercury porosimetry of microcrystalline cellulose tablets: effect of scanning speed and moisture.

The effect of pretreatment and scanning speed of mercury porosimetry on the porosity result of microcrystalline cellulose tablets was studied. The porosity parameters followed were total pore volume, mean and median pore size, and volume pore size distribution. Scanning speed did not affect the total pore volume of tablets compressed from microcrystalline cellulose. With increasing speed, the smallest pores of powder tablets were not properly determined, which increased the mean pore size. The median pore size of tablets compressed from powder and granules decreased and the maximum at the pore size range 500-1000 nm changed towards smaller pores with increasing scanning speed. Scanning speed appears to affect in different ways the samples with different physical structures. In tablet samples, scanning speed affects the volume of the pores at the whole pore size range determined. Thus, it is important to use about the same, reasonably low scanning speed in the measurements when comparing the samples. Swelling of microcrystalline cellulose in tablet samples is observed by mercury porosimetry measurement; a change in the pore structure is detected after storage at 88% relative humidity as increased total pore volumes and median pore sizes. Due to swelling, the maximum at the pore size range 500-2000 nm changed towards larger pores with increasing moisture. Swelling is observed similarly in tablets manufactured from powder and granules. When storing in humid conditions, water fills the smallest pores of microcrystalline cellulose powder tablets, hinders the intrusion of mercury and, thus, the mean pore size increases. Contrary to this, the volume of the smallest pores of granule tablets compressed with the highest compression pressure increased with increasing moisture. Careful pretreatment before the measurements is important.

Cellulose↗

Pharmacokinetic profile of a new controlled-release isosorbide-5-mononitrate 60 mg scored tablet (Monoket Multitab).

The influences of food, tablet splitting, and fractional dosing on the pharmacokinetics of a new controlled-release double-scored tablet containing 60 mg isosorbide-5-mononitrate (Monoket Multitab) were investigated in healthy male volunteers. Food interaction was evaluated after single dose administration under fasted conditions and after a standard high-fat breakfast. The effect of tablet splitting was assessed at steady-state, after 5 days of once daily dosing with the tablet taken intact or trisected. The influence of fractional dosing was assessed after 1 and 6 days of daily regimen of 40 mg in the morning (2/3 of a tablet) and 20 mg in the evening (1/3 of a tablet). The pharmacokinetics of isosorbide-5-mononitrate after taking the tablet intact or in three fragments were very similar with a mere 10% increase of maximum plasma concentration (C(max)) for the latter, while the time to peak (T(max)) decreased from 5 to 4 h and areas under the concentration vs. time curves (AUCs) were virtually unchanged. Morning trough concentration reached 53 and 46 ng/ml, respectively. Administration of the intact tablet after a high-fat breakfast increased C(max) by 18% and AUC by 21%, and slightly delayed T(max) from 5 to 6h. During fractional dosing, morning and evening C(max) reached 364 and 315 ng/ml on the first day, and 373 and 300 ng/ml on the 6th day, respectively. The ratio of AUC(0-24 h) on the last day to AUC(infinity) on the first day, was 82.1% (confidence limits 71.7-94.1%) possibly resulting from peripheral volume expansion. The release characteristics of Monoket Multitab are thus moderately influenced by concomitant intake of food and to a very minor extent by tablet breaking. Fractional dosing allows to achieve lower peak and higher morning trough levels, while total exposure is comparable to that during once daily dosing (AUC(0-24 h, s.s.) of 5.55+/-1.78 and 5.71+/-1.08 microg h/ml).

Adult↗

Influence of tableting on the enzymatic activity of different alpha-amylases using various excipients.

The purpose of the study was to show the influence of compression pressure on the enzymatic activity of different types of alpha-amylases and to analyze the loss of activity of alpha-amylase in mixtures with different excipients. Following that, the properties of excipients used for tableting enzymes were evaluated. Tablets were produced on an instrumented single punch tableting machine. The pure amylases were tableted with increasing graded compaction pressures. Mixtures were tableted to different maximum relative densities, rho(rel,max). The remaining enzymatic activity of the alpha-amylase in the tablets was determined by the starch iodine reaction. The results show a difference between different types of alpha-amylase depending on their origin and additives. Enzymatic inactivation occurs for the pure materials at all pressures used. It is initiated during and continues after compaction. It can be inhibited by freezing the tablets. Another possibility is to tablet the enzyme in a mixture with excipients, which prevent inactivation by softly embedding the enzyme. One example which even stabilizes alpha-amylase at high volume reduction is kappa-carrageenan. In conclusion, enzymatic inactivation can be markedly reduced when excipients are used for tableting, which require little compaction pressure and are able to release the mechanical stress in the form of expansion.

Carrageenan↗

Modeling of theophylline release from different geometrical erodible tablets.

The aim of this study is to reveal statistically how various geometrical shapes such as triangle, cylinder, half-sphere affect the release rate of the active substance called theophylline in erodible hydrogel matrix tablets. We have tried to indicate these changes in the release rate of theophylline by supporting our aim with the mathematical equations developed by Hopfenberg and Katzhendler et al. The model developed by Hopfenberg assumes that drug release occurs from the primary surface area of the device but Katzhendler et al. (I. Katzhendler, A. Hoffman, A. Goldberger, M. Friedman, Modelling of drug release from erodible tablets, J. Pharm. Sci. 86 (1997) 110-115), described a situation where the erosion rates of the tablet are different in the radial and axial directions. Hydrogel matrix tablets were prepared with hydroxypropylmethylcellulose (HPMC E(50)) possessing different geometrical shapes as triangular, cylindrical and half-spherical using experimental design. When the dissolution results have been evaluated, it has been observed theophylline release from different geometrical erodible tablets fitted with that of the Katzhendler et al., equation. This equation which was suggested for cylindrical tablets was also used to interpret half-spherical and triangular tablets. According to the above stated equation, n has been determined as 4 for triangular tablets and 1.5 for half-spherical tablets and we have also suggested that, these n values could be used in the kinetic programs.

Drug Delivery Systems↗

Near-infrared spectroscopy as a nondestructive alternative to conventional tablet hardness testing.

PURPOSE: Near-infrared reflectance spectroscopy (NIRS) was used to evaluate and quantify the effect of compression force on the NIR spectra of tablets. METHODS: Flat, white tablets with no orientation (scoring, etc.) were manufactured on a Stokes Rotary Tablet Press. NIRS was used to predict tablet hardness on the following four formulations and one placebo matrix: hydrochlorothiazide (HCTZ) 15% and 20% in a placebo matrix (microcrystalline cellulose and magnesium stearate), and chlorpheniramine maleate (CTM) 2% and 6% in a placebo matrix. Five or six levels of tablet hardness from 2 to 12 kg were used for each formulation. Laboratory hardness data was compared to NIR reflectance data using a NIRSystems Rapid Content Analyzer. Multiple linear regression and partial least squares regression techniques were used to determine the relationship between tablet hardness and NIRS spectra. RESULTS: An increase in tablet hardness produced an upward shift (increase in absorbance) in the NIRS spectra. A series of equations was developed by calibrating tablet hardness data against NIR reflectance response for each formulation. The results of NIRS hardness prediction were at least as precise as the laboratory hardness test (SE = 0.32). CONCLUSIONS: A NIRS method is presented which has the potential as an alternative to conventional hardness testing of tablets.

Chlorpheniramine↗

Tablet formulation study of spray-dried sodium diclofenac enteric-coated microcapsules.

Sodium diclofenac enteric-coated microcapsules were prepared by a spray-drying technique with Eudragit L 30D as enteric-coating material. The spray-dried powder, mixed with neocel or flo-starch, or the mixture of neocel and flo-starch (weight ratio, 1:1) was directly compressed into a tablet. The micromeritic properties of the spray-dried powder and the mixed powder for tableting were investigated. The flowability of the spray-dried powder was poor but improved after incorporating the excipients. The release rates of sodium diclofenac from the spray-dried powder, the mixed powder before tableting, and the tablets were determined in 0.1 N HCl solution, pH 6.8, phosphate buffer solution, distilled water, and pH-changed medium. The results indicated that the spray-dried powder, the mixed powder before tableting, and the tablets all exhibited enteric-coated release properties; these powders and tablets showed some resistance to stimulated gastric acid and then released drug more rapidly in pH 6.8 buffer solution. The weight ratio of neocel to flo-starch plays an important role in controlling the release of sodium diclofenac from enteric tablets. The 1:1 weight ratio of neocel to flo-starch was more suitable for designing the microdispersed sodium diclofenac enteric-coated tablets.

Acrylates↗

Thermophysical properties of some pharmaceutical excipients compressed in tablets.

PURPOSE: Thermophysical properties of three tableting excipients; microcrystalline cellulose, lactose and dicalcium phosphate dihydrate were observed to evaluate their ability to resist temperature induced changes in tablet form. METHODS: Two thermophysical parameters, thermal diffusivity and specific heat, were measured by a pulse heating method. The materials were also evaluated by differential scanning calorimetry (DSC). RESULTS: Microcrystalline cellulose in tablet form was found to be rather insensitive to heating and cooling treatments, even though the tablets seemed to remain in a stressed state four weeks after tableting. This stress, indicated by low temperature anomalies, was observed by the pulse method, but not by DSC. When magnesium stearate was incorporated as a lubricant within the microcrystalline cellulose powder, the thermophysical parameters indicated that the internal structure of the tablets changed with heating and cooling. Magnesium stearate eliminated the low temperature anomalies as well. The heat treatment changed the thermophysical properties of tablets made of the crystalline excipients lactose and dicalcium phosphate dihydrate, permanently causing irreversible structural changes. CONCLUSIONS: The melting of the lubricant together with enhanced stress relaxation in the structure of microcrystalline cellulose most probably caused the improved thermal diffusivity. The observed thermophysical changes with the crystalline excipients were due to changes in tablet's structure and material. The combination of methods used was found to be an accurate and reliable way to obtain useful information on the structural changes and material relaxations of intact tablets during temperature treatment and age-related changes in material properties.

Calcium Phosphates↗

Analysis of in vitro dissolution of whole vs. half controlled-release theophylline tablets.

Controlled-release (CR) drug products dissolve more slowly than conventional-release products, reflecting their quality of sustaining a prolonged therapeutic effect. A frequent practice with scored tablets when only half the dosage is desired is to divide the tablet at the score mark and administer only half of the product. The dissolution characteristics of the divided tablets are unknown. It is only an assumption that the halved tablet behaves similarly to the whole tablet both in vitro and in vivo. A series of in vitro dissolution analyses was performed on whole and half CR theophylline tablets from different manufacturers. Statistical tests were carried out between the dissolution results of whole and those of halved tablets to determine whether the mean overall percentages dissolution (averaged over sampling times) were similar and whether the patterns of percentage dissolution over time were similar. The dissolution of halved tablets was slightly faster compared to that of intact (whole) tablets. However, these small differences were not large enough to cause concern or to require bioavailability studies.

Delayed-Action Preparations↗

Tablet dissolution affected by a moisture mediated solid-state interaction between drug and disintegrant.

PURPOSE: To investigate the cause for decrease in delavirdine mesylate 200 mg tablet dissolution upon exposure to high humidity. METHODS: Dissolution testing was performed using the USP 2 (paddle) apparatus. Water in tablets was measured by Karl Fischer titration. 13C CP/MAS NMR was used to identify and quantify delavirdine form changes in tablets. FT-IR spectroscopy was used to monitor delavirdine form change in tablets and component mixes, and to investigate a solid state reaction with the disintegrant. RESULTS: Dissolution extent of delavirdine mesylate 200 mg tablets was substantially decreased after exposure to high humidity. This effect is related to the amount of water present in the tablet matrix. 13C CP/ MAS NMR detected about 30% conversion from the mesylate salt of delavirdine to its free base form in the tablet matrix. FT-IR spectroscopy demonstrated that a solid state reaction occurs between the freed methanesulfonic acid and the carboxyl sites on the croscarmellose sodium disintegrant. CONCLUSIONS: Water is thought to act as both a reaction medium and a plasticizer for croscarmellose sodium, facilitating protonation of the carboxyl sites on the disintegrant. This reaction has the potential to occur for any acid salt of a free base. The limiting solubility of delavirdine free base formed in the tablets accounts for much of the decrease in the extent of dissolution. A change in inter-particle bonding can explain the reduction in tablet deaggregation during dissolution.

Carboxymethylcellulose Sodium↗

Correlation and prediction of moisture-mediated dissolution stability for benazepril hydrochloride tablets.

PURPOSE: This report investigated dissolution stability of benazepril hydrochloride tablets. METHODS: Reduction in dissolution rate was observed for benazepril hydrochloride tablets when they were subjected to stressed storage condition (40 degrees C/75% RH) for prolonged periods of time (1-3 months). Moisture contents of initial and stressed tablets were measured by Karl Fischer method. Comparative thermal and physical characterizations of initial and stressed tablets were also performed. A mathematical model that was used to predict possible reduction in dissolution rate was proposed and validated using experimental data. RESULTS: It was found that there was a direct correlation between moisture content of benazepril hydrochloride tablets and their percentage of dissolution at 10 min. At moisture content below 3.5%, there were no significant changes in dissolution values. Beyond that point, however, a close to linear decrease in dissolution was observed as a function of increase in moisture content. Results from thermal and X-ray analysis have ruled out possible changes in drug substance. Other physical characterization, such as scanning electron microscope and mercury porosimetry measurements, revealed changes in core structure of stressed tablets vs. initial tablets. Based on results from these measurements, "preactivation" of disintegrant was identified as the mechanism for reduction in dissolution rate above critical moisture content. A simple physical model for moisture uptake of benazepril hydrochloride tablets was also proposed for predicting when, based on water vapor transmission and critical moisture content, dissolution rate will decline. CONCLUSIONS: Physical changes of tablets mediated by moisture were the main cause for reduction in dissolution. Inclusion of desiccant, although beneficial, cannot prevent reduction in dissolution completely. The simple physical model proposed in this report was found to be useful in predicting the dissolution stability of the dosage form.

Benzazepines↗

Application of transmission near-infrared spectroscopy to uniformity of content testing of intact steroid tablets.

Transmission near-infrared (NIR) spectroscopy was used for the rapid and non-destructive determination of the content of a hormone steroid in single intact tablets. Tablets produced for clinical trial purposes containing 5, 10, 15, 20 and 30 mg (2.94, 5.88, 8.82, 11.76 and 17.64% m/m, respectively) were used to develop calibration models without the need to specially prepare any out of specification tablets. Reference values for the individual tablets used in the NIR calibration models and test set were measured by reversed-phase high performance liquid chromatography (HPLC). Partial least squares regression using standard normal variate transformed second-derivative spectra over the range 800 to 1040 nm gave the optimum calibration model with a standard error of calibration of 0.52 mg per tablet. Measurements of an independent test set gave comparable results (standard error of prediction 0.31 mg per tablet). Measurement errors for a single tablet (RSD < 2.5% for a given active level) were sufficiently small to allow the procedure to be applied to pharmacopoeial uniformity of content testing of batches of these tablets and permitted the non-destructive testing of 30 tablets in under 20 min as compared to 6 h by HPLC.

Calibration↗