Ascorbic acid tablet formulations

Based on the TG and DSC experimental results it can be concluded that the excipients, that is, magnesium stearate, magnesium trisilicate, and Si02, have no substantial influences on the thermal stabihty of ascorbic acid. This result shows that the three compounds can be used (at least from a thermal point of view) as excipients, with no restrictions, for ascorbic acid tablet formulations, since they will not provoke or accelerate the thermal degradation of ascorbic acid. However, by comparison of Tables 3.5 and 3.7, it is evident that the temperature of the... 

Povidone K 25 and povidone K 30 are very good binders for effervescent tablets, as they dissolve rapidly in water to form a clear solution. This particularly applies to effervescent vitamin tablets, e.g. ascorbic acid tablets [368 b]. Tables 65 and 66 give formulations for ranitidine effervescent tablets and multivitamin effervescent tablets as typical examples that were developed on a laboratory scale. For the granulation of multivitamin preparations, it is always preferable to use a fluidized bed. 

Other workers have used the tristimulus parameters to study the kinetics of decomposition reactions. The fading of tablet colorants was shown to follow first-order reaction kinetics, with the source of the illumination energy apparently not affecting the kinetics [49]. The effect of excipients on the discoloration of ascorbic acid in tablet formulations has also been followed through determination of color changes [50]. In this latter work, it was established that lactose and Emdex influenced color changes less than did sorbitol. 

Water-soluble vitamins in formulations have been determined by use of ion-pair chromatography. The vitamins include several B vitamins as well as niacin, folic acid, and ascorbic acid (565). Vitamins D and Da were rapidly separated on reverse phase columns (247) as are vitamins A, D, and E in multivitamin tablets (564). Addition of silver ions to the mobile phase has been shown to increase the flexibility inherent in RPC by complexing with the unsaturated bonds and thereby decreasing the retention factor. This effect is also observed with other unsaturated drug molecules including steroids (247). Vitamin A and related compounds have... 

In the manufacture of tablets it is important to define and appreciate the physical properties of the active substance, in particular particle size and flowability. The technology involved in direct compression assumes great importance in tablet formulations because it is often the least expensive, particularly in the production of generics that the active substance permits. The limiting factors are the physical properties of the active substance and its concentration in the tablets. Even substances such as ascorbic acid, which are not generally suitable for direct compression owing to the friability of the crystals, can normally be directly pressed into tablets at concentrations of 30-40%. Ffowever, this technique is not as suitable if the content of ascorbic acid is higher. This limit may be shifted upward by special direct-compression auxiliaries, for example, Ludipress (BASF). 

The true direct compression process as described earlier almost invariably applies to formulations containing potent active ingredients and where the direct compression properties derive from the diluent. A few substances do possess adequate flow and cohesive properties without the need for pretreatment. These are usually crystalline inorganic salts such as sodium chloride and potassium chloride. Direct compression forms of less potent active ingredients are available e.g., paracetamol and ascorbic acid. These can be directly compressed into tablets, perhaps after the addition of a lubricant. However, such substances are more accurately described as pre-granulated, in that the granulation process—either wet granulation or precompression—has been carried out by the excipient manufacturer. 

A 30-year-old woman, a heterozygote for hypophosphatasia, who had been taking two tablets of a multivitamin formulation (pyridoxine hydrochloride 100 mg, riboflavin butyrate 30 mg, nicotinamide 40 mg, biotin 0.05 mg, ascorbic acid 100 mg) once daily for 6 years, had severe skin eruptions and pruritus on exposure to the sun. The minimum erythema doses for UVB (20 mJ/ cm ) and UVA (4 J/cm ) were lower than normal only for UVB (reference ranges 60-100 mJ/cm for UVB and below 10 J/cm for UVA). Patch and photopatch tests with the constituents of the tablets produced reactions to pjTidoxine and pjridoxal phosphate only. 

Ascorbic acid and derivatives are cited as potential ingredients in cosmetic formulations (876-879). Specific uses involve cosmetic compositions for thermal dispensing (880), dentifrice tablets (881), bath preparations (882), deodorants and mouthwashes (883-886), skin preparations such as skin lightening preparations (887) or protective creams (888-890). The more active areas have been hair and scalp preparations (891,892), hair setting compositions (893), hair bleaching programs (894, 895), and hair dyeing preparations (896, 897, 898). 

It is normally difficult to produce tablets with ascorbic acid by direct compression, but as is shown in Table 174, they can be produced much more readily using copovidone. When this dry binder is added, the hardness of the tablets increases and the friability decreases much more than after the addition of povidone K 30 or hydroxypropylmethylcellulose (HPMC) which had no effect on the hardness in this formulation. Similar results were shown in Fig. 111 for acetaminophen tablets. 

Q6.3 Vitamin C (ascorbic acid) is used in pharmaceutical formulation as an antioxidant and also has a medical use as a vitamin. Tablets of vitamin C may be assayed by titration with complex salts of cerium. The reactions occurring are as follows and are shown in Figure 6.7. 

Thomas, B.R. Fang, X.G. Shen, R Ghodbane, S. Mixed ion pair liquid chromatography method for the simultaneous assay of ascorbic acid, caffeine, chlorpheniramine maleate, dextromethorphan HBr monohydrate and paracetamol in Frenadol sachets. J.Pharm.Biomed.Anal., 1994,12, 85-90 [simultaneous caffeine, chlorpheniramine, dextromethorphan, vitamin C formulations] van der Veen, J. Eissens, A.C. Lerk, C.F. Controlled release of paracetamol from amylodextrin tablets In vitro and in vivo results. Pharm.Res., 1994, 11, 384-387 [plasma pharmacokinetics] Abounassif, M.A. Abdel-Moety, E.M. Gad-Kariem, R.A. HPLC-quantification of diethylamine saliqylate and methyl nicotinate in ointments. J.Liq.Chromatogn, 1992,15, 625-636 [formulations ointments simultabeous diethylamine salicylate, methyl nicotinate acetaminophen is IS simultaneous methyl paraben, propyl paraben... 

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