How to Select Pharmaceutical Excipients?
Pharmaceutical excipients refer to the substances used in the production and
formulation of medicines. They perform multiple functions in pharmaceutical
preparations and are likely to affect the quality, safety and effectiveness of drugs.
Pharmaceutical excipients can be classified into natural, semi-synthetic and fully
synthetic compounds according to their sources. And based on their use, excipients
can be divided into diluents, binders, disintegrants, lubricants, glidants and
anti-caking agents, wetting agents and solubilizers.
Among all varieties of excipients, how to select the most appropriate ones for a
specific drug formulation project? The guidelines below should be taken into
consideration.
The compatibility of the main drug and the excipients should be studied.
When screening and researching drugs with new chemical structures, attention
should be paid to the investigation of the interaction between the main drug and the
excipients. The excipients should have stable properties with no physiological activity,
no influence on the content determination of the main drug and no adverse effect on
the dissolution and absorption of the drug. According to the above principles, when
we select excipients, we must first conduct research on the compatibility of the main
drug and excipients. Through preliminary investigation, we can understand the
excipient-to-excipient interaction and excipient-to-drug interaction, to avoid the
selection of excipients with adverse interactions in prescription design.
For lack of relevant research data, compatibility studies can be conducted. For
example, for solid oral preparations, several kinds of excipients can be selected at
first, and then mix the main drug and excipients with a certain proportion, and put
them under strong light (4500±500Lux), high temperature (60℃) and high humidity
(90±5 %) conditions for 10 days, and finally use HPLC to check whether the content
and related substances changed before and after placing. When necessary, the active
pharmaceutical ingredients (APIs) and excipients can be used for parallel control
experiments to judge whether it is the change of the API itself or the influence of the
excipients. If conditions permit, experiments such as hot plate (DTA or DSC) can be
used to determine whether the main drug interacts with the excipients.
The selection of excipients should be quality centric.
The choice of excipients should first consider the mechanism of action of the drug.
Second, the excipients chosen should meet the characteristics and requirements of
the dosage form. Third, it is a must to study the effect of the excipient’s physical and
chemical properties on the preparation. Changes in the excipient’s physical and
