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Abstract  

A new formulation of nifedipine tablets was prepared. The tablets were conditioned in amber-colored glass containers and placed in a climatized room at 40 °C and relative humidity of 75% for 180 days. Differential scanning calorimetry (DSC) and Thermogravimetry (TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two well-known nifedipine degradation products. There is no evidence of interaction between nifedipine and excipients or degradation products. High performance liquid chromatography (HPLC) was used in the dosage of nifedipine tablets before and after acclimatized exposure. Results show that DSC and TG offer important data for a more detailed assessment of the stability of a pharmaceutical formulation.

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different techniques. Use of IMC therefore offers much potential in field of pharmaceutical science, not only in amorphicity determination but also to study other processes [ 6 – 9 ]. In this study, nifedipine and lactose were chosen as model

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Abstract  

The phase diagrams of nifedipine-polyethylene glycol (PEG) 4000 and nifedipine-mannitol systems have been determined. Heating experiments on thermodynamically equilibrated co-melts revealed eutectic behaviour for nifedipine-PEG 4000 mixtures, with the composition of the eutectic point between 40 and 45%w/w of nifedipine. These observations were supported by optical and hot stage microscopy. Nifedipine and mannitol were negligibly miscible in the solid-state, behaving as a binary system with monotectic characteristics. Application of phase diagrams to the production of solid dispersions is shown to be rational, since they provide valuable information on the state of the binary systems under preparation.

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anticonvulsant [ 14 ]. The use of nifedipine, a calcium-channel blocker, to treat hypertension has been recommended to use in pre-eclampsia [ 15 ]. It significantly reduced the systemic blood pressure without adversely affecting the expected course of pregnancy

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Abstract  

A formulation of nifedipine tablets was prepared in the present research. The tablets were conditioned in amber-colored glass containers and placed in a climatized room at 40°C and relative humidity of 75% for 180 days. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two well-known nifedipine degradation products. The results demonstrated that there is no evidence on the interaction between nifedipine and excipients, or degradation products.

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Abstract  

Nifedipine complexes with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), 2-hydroxypropyl-β-cyclodextrin (2HP-β-CD), randomly methylated-β-cyclodextrin (RM-β-CD) and heptakis(2,6-O-dimethyl)-β-cyclodextrin (DM-β-CD) have been prepared by both kneading and heating methods and their behaviour studied by differential scanning calorimetry (DSC), diffuse reflectance mid-infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). DSC revealed the nifedipine melting endotherm with onset at approximately 171°C for the kneaded mixtures with β-CD, γ-CD and 2HP-β-CD, thus confirming the presence of nifedipine in the crystalline state, while some decrease in crystallinity was observed in the DM-β-CD kneaded mixture. With RM-β-CD, however, broadening and shifting of the nifedipine endotherm and reduction in its intensity suggested that the kneading could have produced an amorphous inclusion complex. These differing extents of interaction of nifedipine with the cyclodextrins were confirmed by FTIR and XRD studies.

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PK: Modification by solvents of the action of nifedipine on calcium channel currents in neuroblastoma cells. Naunyn. Schemiedberg's Arc. Pharmacol. 345, 478-484 (1992) Modification by solvents of the action of nifedipine on

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Abstract  

A well-known photolabile substance, nifedipine, was used as a sample material to test self-constructed irradiation cells and demonstrate their usefulness in photostability studies. The devices were made as accessories for a commercial isothermal microcalorimeter. Several powder samples containing various amounts of moisture were irradiated with monochromatic light as a scan measurement from 700 to 280 nm, and the heat flow evolved in the photodegradation of nifedipine was determined. According to the results, light does not affect the nifedipine molecule directly, but the photodegradation is a result of the combined effects of moisture and light.

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Summary

A simple, sensitive, and convenient HPLC method has been developed, validated, and applied to analysis of nifedipine residues on the stainless-steel surfaces of equipment used in drug manufacture. Cotton swabs moistened with methanol were used to remove residues of the drug from the surfaces; recoveries were 82.26, 86.88, and 88.95% for 25, 125, and 250 μg per swab. The precision of the results, as relative standard deviation (RSD), was <5%. The method was validated over the concentration range 3–50 μg mL–1. Small quantities of residues of the drug and its main impurities were determined by HPLC on an ODS column with methanol-water-phosphate buffer (pH 3; 0.05 m)-sodium heptanesulfonate 65:35:3:0.13 (v/v/v/w) as mobile phase at a flow rate of 0.8 mL min–1. Detection was at 235 nm.

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Schumann HJ, Gorlitz BD, Wagner J: Influence of papaverine, D-600 and nifedipine on the effects of noradrenaline and calcium on the isolated aorta and mesenteric artery of the rabbit. Naunyn-Schmiedeberg 's Arch. Pharmac. 289, 409-416 (1975

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