Dissolution Rate Of Nifedipine Research Articles

Studies in Dissolution Enhancement of Nifedipine

AbstractSolid dispersions containing PVP and PEG, inclusion complex with beta cyclodextrin (Bcyd), and kneaded mixtures with hydrophilic adjuvants such as water-soluble gelatin (WSG) and microcrystalline cellulose (MCC) were prepared in order to enhance the dissolution rate of nifedipine (NF) in simulated gastric fluid. The dissolution rate of NF from solid dispersions increased in the order of PVP K-30 > PEG 6000 > PEG 4000 > pure drug. About a threefold increase in solubility of NF was obsewed from NF-Bcyd inclusion complex. The drug was released at a quicker rate from hard gelatin capsules containing physical mixture of inclusion complex of NF-Bcyd and WSG and also from tablets. WSG promoted wetting of NF by reducing suvace tension. Nifedipine tablets coated with a thin layer of HPMC were found to be stable microbiologically and chemically. The mechanisms of drug release were ascertained using F-test statistics.

Dissolution Characteristics of Nifedipine Complexes with β-Cyclodextrins

Formation of nifedipine complexes with P-cyclodextrin, hydroxypropyt-& cyclodextrin, and DIMEB in solution was studied by the phase solubility method. Solid complexes of nijedipine were prepared by partial and complete solubilization of nifedipine using the freeze- and spray-drying techniques. The complexation led to an improvement in the dissolution rate of the drug. The relative potency of P-cyclodextrins to enhance the dissolution rate of nifedipine was in order: pcyclodextrin < hydroxypropyl-P-cyclodextrin < DIMEB, which clearly fits the magnitude of stability constant data of the complexes. The dissolution rates of the free drug, complexes, and physical mixture of drug and cyclodextrins from constant su@ace area disks were also investigated.

ニフェジピン持効性細粒の溶出特性と光安定性

A sustained release nifedipine fine granules, Sepamit R Granules® (SP-RG), is a product prepared by using the technique of solid dispersion. Dissolution behavior of nifedipine from SP-RG was tested based on the results of incompatibility. The photostability of SP-RG was also tested. Dissolution rate of nifedipine from SP-RG was 12.5% in JP XII 1st disintegration test fluid (pH 1.2) and 100.9% in JP XII 2nd disintegration test fluid (pH 6.8). Dissolution of nifedipine in JP XII 2nd fluid was delayed by moisture absorption during storage (relative humidity of 75% at 20° for 30 days). Dissolution of nifedipine from SP-RG in JP XII 1st fluid was increased by mixing of SP-RG with sodium bicarbonate or heavy magnesium oxide during storage (relative humidity of 75% at 20° for 30 days).Nifedipine in SP-RG packaged with polyethylene cellophan laminate paper completely decomposed after 72 hours, under exposure to light (500 lux), while it was stable even after 30 days with aluminium polyethylene laminate paper.

Solid dispersion obtained from nifedipine and enteric coating agents. I. Dissolution behavior

Dissolution behavior from solid dispersion system obtained from nifedipine and enteric coating agent (hydroxypropylmethylcellulosephthalate and copolymer based on methacrylic acid and methacrylic acid methyl ester) were investigated. The X-ray diffraction data suggested that nifedipine was present in its amorphous form in these systems. Dissolved amounts of nifedipine from the system in JP X 1st fluid (pH 1.2) were poorer than that of nifedipine crystalline. But the dissolution rate of nifedipine from the system, especially nifedipine-hydroxypropylmethylcellulosephthalate, was very rapid and the system showed supersaturated concentration in JP X 2nd fluid (pH 6.8). Dissolution behavior, that is dissolution rate and amount of nifedipine dissolved in the system was better in the case of the use of hydroxypropylmethylcellulosephthalate as carrier than that using copolymer based on methacrylic acid and methacrylic acid methyl ester. The above reason was discussed from the inhibitory effect of these polymers on the crystallization of nifedipine.

Dissolution and Absorption of Nipedipine from Nifedipine-Polyvinylpyrrolidone Coprecipitate

Attempt was made to develop the solid dosage form of nifedipina which showed good absorption rate and total bioavailability. Nifedipine is a poorly water-saluble drug, whom bioavailability is low when administered orally in the crystalline form. Solutions of nifedipine were well absorbed from the gastrointestinal tract. The dissolution rate of PVP-nifedipine coprecipitates exhibited rapid dissolution rate. X-ray diffraction data suggested the lack of crystallinity in the coprecipitate. The relation between the dissolution rates and average molecular weights of PVP was studied. Nifedipine in the copretipitate was chemically stable to heat and humidity, but the dissolution rate of nifedipine from the coprecipitate stored at 21° and 75% R.H. markedly decreased. X-ray diffraction data revealed that it might be due to the transformation of amorphous form of nifedipine to crystalline form under higher relative humidity. The gastrointestinal absorption of nifedipine in beagle dogs after oral administration of the coprecipitate was increased than that after oral adniniatration of the physical mixture.