Oral Liquids Market Really a Niche

IMPORTANCE OF EXCIPIENT SELECTION IN THE PROCESS OF ORAL LIQUID FORMULATION DEVELOPMENT 

Ideally, the pH at which the drug is most stable would also be close enough to the solubility for delivering the desired dose in approximately 5 mL. Requiring patients to take more than lOmL at a time may not be advisable because of lower patient compliance (variability). In this scenario, a simple oral solution or syrup formulation may be developed. However, if the pH at which the drug is most stable is not one at which there is enough solubility, a suspension formulation may be required. 

A quick means to identify whether or not a drug may be more suitable for solution or suspension is to overlap the pH-stability profile with the pH-solubility profile. This overlap creates a window, which may suggest which dosage form might be most desirable and subsequently the type of excipients needed. The overlapped figures below demonstrate for aspirin (which is a weak acid) that the pH of greatest stability is also the pH at which there is low solubility (Fig. 1). 

The decision to develop a solution versus syrup versus suspension can also be influenced by other factors. The desired release profile of the drug may lead to the 

Once preformulation screening has identified which excipients are able to stabilize the API, a series of prototype formulations can be developed, which will be more reflective of the targeted quantities of excipients and drugs present in the final 

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