Nifedipine Ethanol

We describe below the use of halloysite nanotubules for entrapment and the subsequent release of three drugs Nifedipine (anti-anginal), Furosemide (anti-hypertension and diuretic), and Dexamethasone (synthetic corticosteroid). To increase the loading of these poorly soluble drugs in the tubules, we loaded them into a water-alcohol co-solvent solution (0, 10, and 50% ethanol). 

The dielectric constant of a solvent plays a significant role in solubility and stability of the solute. Few studies relating to the dielectric constant of the solvent medium to the photodegradation rate have been undertaken. Thoma and Klimek (8) reported that the improvement in the photostability of nifedipine noted by them is due to an increase in dielectric constant in both ethanol/water and propylene glycol/water mixtures. 

Carbon-11 labelled calcium channel antagonists C-nifedipine, C-nisoldipine, C-nitrendipine and C-CFj-nifedipine possessing vasodilating and hypotensive properties have been synthesized using a modified Hantzsch-type cyclocondensation proce-dure . Condensation of aldehydes 242, 243 and 244 with 3-aminocrotonic acid esters 245, 246, 247 and with acetoacetic ester 248 produced in one pot after 12 hours reflux in dry ethanol the methyl sulphonylethyl protected dihydropyridines 249-252. Deprotection of the carboxylic acids by alkaline hydrolysis followed by conversion into the dihydropyridine monocarboxylic acids 253-256 gave potassium salts in situ, and subsequent methylation with CH3I produced the corresponding labelled title compounds 257-260 (equation 102),... 

Drugs corticosteroids (Sampson 1995 McAfee et al. 1984), ethanol (McAfee et al. 1984), cyclosporin, azathioprine, ranitidine, nifedipine, procainamide (Sampson 1995), others... 

Meyer and co-workers were one of the first groups to use preformed enamines to synthesize 1,4-dihydropyridines in their synthesis of unsymmetrical fiased nifedipine analogs. Michael addition of alkylidene acetoacetic esters substituted with various aryl groups 188 and enaminocarbonyls 189 (where = 1 or 2) in the presence of refluxing ethanol led to the corresponding fused systems 190 in good yield. 

Ley and co-workers recently used magnesium nitride as a source of ammonia for the Hantzsch synthesis of 1,4-dihydropyridines in high yield. Optimized conditions involved the reaction of 4.5 equiv ethyl acetoacetate 180 and 2 equiv of 2-nitrobenzaldehyde 181 with 1 equiv of magnesium nitride (0.9 M NH3 concentration) in a refluxing solution of ethanol and water (6.5 equiv) for 16 h. The corresponding 1,4-dihydropyridine, in this case nifedipine, was produced in 84%. A number of other 1,4-... 

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