Determination of actives in tablets and capsules

In the earliest NIR assays, tablets and capsules were not analyzed intact. Before NIR spectral collection, drugs were extracted from the matrix into solution. The first reported use of NIR for tablets was by Sherken in 1968 [115]. In this study, meprobamate in tablet mixtures and commercially available preparations was assayed. Two wavelengths, corresponding to the symmetric and asymmetric stretching modes of the primary amine group in the drug molecule, were used. 

Allen used NIR for the quantitative determination of carisopro-dol, phenacetin, and caffeine [116]. Twenty tablets were pulverized and an aliquot dissolved in chloroform was measured. Standard solutions of carisoprodol, phenacetin, and caffeine were scanned between 2750 and 3000 nm. Caffeine and phenacetin were determined at 2820 nm (carisoprodol) and 2910 nm (phenacetin), with caffeine determined at 3390 nm. The coefficient of variation (CV) was 1.4% or less. 

In 1977, Zappala and Post used NIR for meprobamate in four pharmaceutical preparations tablets, sustained-release capsules, suspensions, and injectables [117]. The NIR method was an improvement over that introduced by Sherken it took advantage of a meprobamate (primary amine) combination band at 1958 nm, not subject to the interference suffered by the peak at 2915 nm. Twenty tablets or capsules were pulverized, and an aliquot dissolved in chloroform was scanned. Nine commercial products from four manufacturers were analyzed. The coefficient of variation was 0.7% for tablets and 1.3% for capsules (1.5% for the reference method). 

In 1990, Corti et al. used an extraction prior to NIR to improve the detection limit [118]. Oral contraceptives were used in the study for ethinyl-estradiol (ETH) and norethisterone, two S5mthetic hormones. Qualitative and quantitative analyses were desired. Tablets of 80 mg (0.05 mg ethi-nylestradiol and 0.25 mg norethisterone) were extracted with chloroform 

Pharmaceutical and medical applications of near-infrared spectroscopy 

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Pharmaceutical assays, including qualitative analysis, quantitative analysis, determination of actives in tablets and capsules, and considerations for intact dosage form analysis... 

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