Amide ester amides: amide ester lactam drugs are hydrolyzed to generate the corresponding acids and amines or hydrolyzed to unlock the ring.

Urea and hydantoins: Urea drugs such as barbiturates, phenytoin, caffeine, tolbutamide and other ureides can also be hydrolyzed.

Hydrazides: For example, isoniazid generates isonicotinic acid and hydrazine after hydrolysis.

Phenolic ester＞Alcohol ester＞ureide＞hydrazide＞amide

The rate of hydrolysis depends on the electron cloud density of the carbon atoms in the carbon base.

If there is a large space substitution on both sides of the carbon group of the ester or amide, the hydrolysis rate will be slowed down due to steric hindrance.

The presence of water is a necessary condition for hydrolysis reaction. Drugs that are easily hydrolyzable should be waterproof and moisture-proof during production, storage and use, especially when the temperature rises.

The hydrolysis reaction of esters is reversible and generally slow.

The hydrolysis rate of drugs accelerates with the increase of heating temperature. The longer the time, the more decomposition occurs.

The solvent added to the drug has a certain impact on the hydrolysis of the drug.

Improper diluent in the drug can accelerate the hydrolysis of the drug, so it should be chosen carefully.

EDTA-2Na (0.05%) is often added to drugs to slow down hydrolysis.

Introducing as little moisture into the drug as possible during production and avoiding the entry of external moisture during storage and use is one of the ways to prevent drug hydrolysis.

In order to prevent or delay the hydrolysis of drugs, the production process procedures of drugs prepared into aqueous solutions should strictly comply with the quality standards of the Pharmacopoeia, and the pH value range should be strictly adjusted and controlled.

In order to prevent or alleviate drug hydrolysis, temperature must be controlled in production and storage.

After the drug is ionized in water, when the charge is the same as the charge of the ion with catalytic hydrolysis activity, adding a solute with a mechanical electrical constant can increase the stability and delay hydrolysis.

For example, adding strong electrolyte sodium chloride to atropine sulfate injection can increase stability and delay hydrolysis.

Drugs with aldehyde groups have certain reducing properties and can be oxidized.

The hydroxyl group of alcohols generally has weak reducibility, but when a carbon group, hydroxyl group, amino group, etc. are connected to the carbon chain of an alcoholic hydroxyl group, its reducibility is enhanced and it is easier to be oxidized, even by air.

Drugs with phenolic hydroxyl groups have strong reducing properties, especially drugs containing polyphenolic hydroxyl groups.

Fats and aromatic heterocycles with sulfur groups, disulfide bonds, sulfur heterocycles, etc. are all reducing.

Low-oxide nitrogen-containing drugs such as hydrazines and amines have certain reducing properties.

are easily oxidized.

Drugs containing metal elements with low oxidation number have reducing properties and can be oxidized to high oxidation number metal ions or high oxidation number metal organic compounds.

It is basically caused by oxygen in the air. The auto-oxidation process of free radicals is mostly seen in the deterioration reaction during drug storage.

Most of them are ionic oxide layers caused by chemical oxidants, which are used for qualitative identification or content determination in drug analysis.

The presence of oxygen is a necessary condition for the auto-oxidation of drugs. During the auto-oxidation process, oxygen and drugs form peroxides, causing the drugs to deteriorate.

Light energy activates oxygen molecules into reactive oxygen species to catalyze the formation of free radicals, triggering oxidative chain reactions of drugs and also causing luminescent degradation.

The reaction speed is really fast when the temperature rises. This is a general rule of chemical reactions, and the oxidation reaction is no exception. The oxidation reaction accelerates several times when the temperature rises by 10°C. During the production and storage of drugs, attention should be paid to temperature control.

Affects the redox potential of certain drugs.

Affects the subsequent reactions of certain drugs, causing them to become irreversibly oxidized.

Metal ions come from raw materials, excipients, containers or solutes and often catalyze the auto-oxidation of certain drugs.

The polarity of the solvent has a certain impact on the auto-oxidation of some drugs.

Adding a reducing substance that is stronger than the drug to the drug will cause the reducing substance to be oxidized first, thus preventing the drug from being oxidized by air. This is one of the principles of antioxidants.

Mainly after the absorption of semi-solid drugs in solution, optical isomerization can also occur due to the influence of other factors.

For example, hyoscyamine is a left-handed form, which will be partially converted to a right-handed form when heated, that is, racemization.

Similar to racemization, the difference is that the group of only one asymmetric carbon atom among the multiple asymmetric carbon atoms in the structure undergoes stereosterization.