Dicalcium phosphate dihydrate, effect

Tablets were prepared either with an insoluble (dicalcium phosphate dihydrate), a soluble (6-lactose) or a moderately soluble filler-binder (a-lactose monohydrate). As a disintegrant four different starches (com, rice, potato and tapioca) were used. As a comparison the effect of two super-disintegrants (crospovidone and sodium starch glycolate) was studied. The disintegrants were added at two concentration levels. The compression load was adjusted in order to obtain tablets with comparable initial cmshing strengths.

Tablets prepared with dicalcium phosphate dihydrate increased in crushing strength due to increasing temperatures (A,sir(s) ). The relative humidity had a negative effect on the SIR of crushing strength of the tablets prepared with dicalcium phosphate dihydrate, except for the tablets prepared with potato starch. Also a significant interaction between the temperature and relative humidity effect was seen (A3,sir(S) 0), indicating that the effect of the relative humidity on the SIR of crushing strength of dicalcium phosphate dihydrate tablets depended on the level of temperature and vice versa.

The a-lactose tablets were influenced by the relative humidity too (y5, siR(S) is significant) but the effect was smaller than for the dicalcium phosphate dihydrate tablets. From the tablets investigated, the 6-lactose tablets were least influenced by storage. 

Each combination behaves differently after storage. In all cases there was an effect of the starch concentration (y i sir(d) is significant). In most cases the relative humidity as well as the interaction between the relative humidity and the disintegrant concentration plays a role in the disintegration time of tablets prepared with either lactose. The dicalcium phosphate dihydrate/rice starch combination is influenced very strongly by the three factors studied. This combination is not suitable for use in tropical countries. Neither is the combination of B-lactose and crospovidone. 

Landln M, Martinez-Pacheco R, Gomez-Amoza JL, Souto C, Concheiro A, Rowe RC. The effect of country of origin on the properties of dicalcium phosphate dihydrate powder. Int J Pharm 1994 103 9-18. 

Landin M, Rowe RC, York P. Particle size effects on the dehydration of dicalcium phosphate dihydrate powders. Int J Pharma 1994 104 271-275. 

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