Compendium of Pharmaceutical Excipients for Vaginal Formulations

• Excipients

Global research in pharmaceutical sciences will acquire
new dimensions in the post-GATT (General Agreement
in Trade and Tariff) era. The pharmaceutical industry
currently is focused on the identification and
development of novel leads from areas such as biotechnology,
combinatorial chemistry,molecular modeling, and genetic engineering.
The leads coming from these varied sources will require
specialized formulation techniques and ingredients. At
the same time, the process of discovering new drugs is a costly
proposition and requires input from the basic as well as applied
sciences. Research organizations that do not have adequate expertise
or vision tend to fall out rapidly. The alternative approach
for such organizations would be to develop new dosage
forms or formulations using novel excipients for the existing
drugs that offer distinct benefits over the conventional formulations.
Recent developments in pharmaceutical legislation, regulatory
guidelines, and licensing policies have led to increased
awareness of the properties and roles of excipients in formulations.
A careful use of excipients can lead to the development of novel delivery systems that are both effective and economical.
These innovative formulations also may offer life extension
to drugs in the form of new patents, extending the product life
cycle and adding to the market share of the company.
A formulation can be regarded as a system comprising an active
molecule along with some inert ingredients (see Figure 1).
According to the definition given by the International Pharmaceutical
Excipients Council (IPEC), “Excipients are substances,
other than the active drug substance or finished dosage
form, which have been appropriately evaluated for safety and
are included in drug delivery systems for specific functions” (1).
This definition indicates that excipients are to render easy processing
of the drug delivery systems, to protect, support, or enhance
stability, bioavailability, and patient compliance. They
also assist in product identification and are important for overall
safety and effectiveness of the drug delivery system during
storage or use. These ingredients render specific properties to
a formulation and thus represent an important aspect of formulation
design and optimization. Selection of the type and
amount of excipient is dictated by the target formulation profile
and is a major challenge for the pharmaceutical scientist.
Traditionally the ingredients of a formulation “other than
active ingredient” were known as inactive ingredients. In the
present day, where these inactive ingredients are known to play
a crucial role in designing a formulation and to provide desirable
characteristics, the term excipient is more commonly used.
The equivalent of activity in an excipient is functionality, which
refers to special attributes that the ingredient can provide to a
formulation. Developing a new excipient is as complicated as
developing a new drug molecule; therefore, excipients manufacturers
tend to opt for an easier route for value-added specialty
excipients. Knowledge and understanding of the ingredients
are extremely useful to a product development scientist.