Mixture Of Dicalcium Phosphate Research Articles

Synthesis of calcium-deficient hydroxyapatite in the presence of amphiphilic triblock copolymer

Calcium-deficient hydroxyapatite (CDHA) nanoparticles were prepared in the presence of amphiphilic triblock copolymer (Pluronic). The size of products decreased to submicron by the addition of Pluronic. FT-IR, XRD and XRF analyses confirmed that a mixture of dicalcium phosphate, octacalcium phosphate and HA was synthesized without using Pluronic, in which the Ca/P molar ratio was 1.28. On the other hand, CDHAs were mainly produced by the addition of Pluronic and the Ca/P molar ratio was in the range of 1.51−1.55. In addition, the CDHAs transformed to rod-like nanoparticles after thermal treatment.

Influence of the granulation technique and starting material properties on the lubricating effect of granular magnesium stearate.

Magnesium stearate has been granulated in four ways to produce lubricant granulations with different properties. The lubricating properties, as well as the tablet properties with the granulated lubricant, were evaluated on tablets prepared from a mixture of dicalcium phosphate, corn starch and microcrystalline cellulose. The lubricating effect of the magnesium stearate granulations showed a similar pattern regardless of the granulation technique used except for a granulation with providone. Increasing the particle size of the magnesium stearate granulation increased the amount of lubricant required to obtain lubrication similar to powdered magnesium stearate. Variations in the specific surface area of the starting materials could be masked by using them in granular form.

Hydrothermal synthesis of hydroxyapatite from natural source.

Dicalcium phosphate dihydrate (DCPD) and anhydrous dicalcium phosphate (DCPA) extracted from a by-product in a manufacture of gelatin from bovine bone are used as starting materials for the hydrothermal synthesis of hydroxyapatite (HA) at temperatures of 160 and 200 degrees C under vapor pressures of 1 and 2 MPa, respectively. The suspension of DCPA with water gives a mixture of DCPA and HA as product but after adjusting the Ca/P molar ratio to 1.50 and 1.67 by addition of Ca(OH)(2), a single phase of HA with needle-like crystals is obtained. DCPA whiskers are produced in the suspension of DCPD with water but, on addition of Ca(OH)(2), the product obtained is again, a mixture of DCPA and HA. The coexistence of DCPA and HA is observed not only in the acidic region at pH 4.6 which is close to the known quasi-invariant point but also in the basic region at pH 12.3. Without addition of Ca(OH)(2) to the system, the complete conversion of DCPA or DCPD to HA is not possible.

The Effect of Formulation on 1–131 DissolutionIn Vitrofrom Sodium Iodide Capsules

AbstractBecause of the importance of the bioavailability of 1–131 for thyroid uptake studies and thyroid therapy, the present investigation was conducted to determine the influence of diluents, type of lubricant and the concentration of lubricant on the in vitro release rate of 1–131 from 1–131 sodium iodide capsules. Formulations and 1–131 sodium iodide capsules were prepared in-house and dissolution profiles determined using the U.S.P. XXII Dissolution Test. Distilled water was employed as the solvent. Lactose only, calcium phosphate only, a mixture of dicalcium phosphate—Avicel PH 101 and a sodium phosphate formulation consisting of lactose, L-cysteine hydrochloride and sodium phosphate were chosen as diluents. Several concentrations of the lubricant magnesium stearate were employed. The influence of 3% or 5% talc as the lubricant was studied using the sodium phosphate formulation.The results of the study demonstrated the influence of the formulation on the dissolution of 1–131 when the concentration o...