Polyols are used in pharmaceutical products, either as excipients or as Active Pharmaceutical Ingredients (API). Compared to the use of polyols as API, the volumes of polyols used as excipients are considerably higher.
Polyols used as excipient
Especially in modern formulations, like consumer friendly lozenges or chewable tablets, polyols have gained popularity due to their sweet taste and tooth-friendliness. But also in conventional tablets the usage of polyols is increasing. Compared to the most commonly used pharmaceutical excipient lactose, polyols have some important advantages:
- More and more active ingredients are derived from biotechnological processes. These actives are often very efficient but also extremely reactive. Polyols do not contain reducing sugars, thus the unwanted reaction between the amino-groups of the active and the reducing sugar (like lactose) can be prevented. In addition, non-hygroscopic polyols are used in case a very water-sensitive API has to be formulated.
- Some polyols have a very low hygroscopicity which makes them the excipient of choice in the formulation of water sensitive API that tend to degrade fast when residual water is present in the final dosage form.
- The European polyol suppliers offer their pharmaceutical customers polyols in various particle size ranges and in functionalised granulated or spray-dried forms. Suitable grades can be found for use in conventional pharmaceutical production processes such as dry or wet granulation but equally so to facilitate modern pharmaceutical production processes like direct compression.
Today, polyols are used in the following medicinal dosage forms:
- In sugar-free medicinal syrups, polyol syrups are used as pleasantly sweet tasting vehicle for the medication.
- In tablets and capsules, various polyols can be used to obtain optimal final dosage forms. They can serve multiple purposes:
- Diluent or filler used to produce appropriate dosage form size
- Binder to obtain tablets with the proper cohesiveness and strength
- Sweetening agent
- Taste masking agent to take away the often bitter or astringent off-taste of the API.
- Coating agent
- In water based ointments and gels polyols are used as humectant or moisture retention agent to prevent the ointment from hardening upon storage.
- In soft gelatin capsules, polyols act as plasticizer to optimize the flexibility of the capsules.
- In freeze-dried products, polyols are used as lyophilisation agent to produce suitable physical properties and stability.
- In liquid formulations, polyols may alter the osmotic potential and act as tonicity agent.
Several guidelines are developed by IPEC Europe (International Pharmaceutical Excipients Council), e.g. the Joint IPEC-PQG Good Manufacturing Practices Guide or the IPEC Risk Assessment for Pharmaceutical Excipients. Part I – Risk Assessment for Excipient Manufacturers.
Polyols used as Active Pharmaceutical Principle (API)
First medical indication of polyols as active ingredients was the treatment of constipation. Even today polyol solutions are used as enema before examinations of the colon. Nowadays the main indication for polyols as pharmaceutical active is the reduction of brain swelling and acute kidney failure. Here, polyols act as osmotic diuretics and remove excess water out of the body. These life-supporting formulations are administered as infusion solutions and usually contain 10-20% of polyol in sterilised water.
Polyols for use as APIs need to correspond to special requirements regarding their purity. These requirements are defined in the European (EP), US (USP) and Japanese(JP) Pharmacopoeias. In addition the manufacturing process of these polyols needs to be in accordance with the “current Good Manufacturing Practices” (cGMP). The European polyol manufacturers adhere to these regulations and offer suitable products for the use of polyols as API.
To know more about the APIs regulation for pharmaceutical applications, please download the summary from here.