Contains phenyl-1,4-dihydropyridine core

basic skeleton

Reducing property, the dihydropyridine ring is reducing

Oxidizing property, most benzene rings have nitro groups, nitro groups are oxidizing properties

Dissociation property: the interaction between dihydropyridine drugs and bases can cause dissociation of hydrogen at positions 1 and 4 of the dihydropyridine ring.

Photo-instability. The two hydrogen atoms at 1 and 4-position of the dihydropyridine ring are particularly active in dissociation and reactivity. They are extremely unstable when exposed to light, are easily oxidized, and are prone to photocatalytic disproportionation reactions under light conditions.

Optical rotation, the C-4 position is mostly a chiral carbon atom, and the chiral enantiomer has optical rotation

Absorption spectral characteristics, with aromatic rings and characteristic absorption in the ultraviolet region

Reacts with ferrous salts

Reacts with alkaline test solution

precipitation reaction

Diazotization-coupling reaction

UV spectrophotometry

Infrared spectrophotometry

thin layer chromatography

HPLC

It is unstable when exposed to light and is prone to photocatalytic disproportionation reactions and the introduction of impurities. Therefore, it is required to conduct relevant substance inspections under light-proof conditions.

Inspection of degradation impurities

Inspection of other alkaline impurities

For the dissolution determination of nimodipine tablets by ChP and BP, acetate buffer containing 0.3% sodium lauryl sulfate was used to promote the dissolution of nimodipine in the preparation.

Using Ce (SO4) 2-position titrant, quantitative redox titration using the oxidizing property of Ce4

When the acidity is low, Ce4 is easily hydrolyzed, so the titration must be carried out under strongly acidic conditions.

Ce4 is yellow and Ce3 is colorless, so Ce4 itself can be used as an indicator, but it is not sensitive enough. Usually o-phenanthroline is used as indicator, and the end point is sensitive.