While topical delivery is highly effective for certain compounds, this method typically requires that the condition being treated is a surface ailment (such as for the skin or eye), however this is not always true as patches such as the nicotine patches are able to delivery nicotine systemically using a topical method.4
The most complex method, oral delivery, is also the most common and convenient for the majority of patients.2 This mode of delivery requires a lot more forethought and evaluation of a compound, which has resulted in many different types of delivery platforms. The preferred oral delivery system is vial pills, but even pills have a fairly substantial variety. Some pills use an outer coating (capsule) that allows for the pill to make it through the stomach without substantial loss to the compound. Some are just the drug mixed with an inert filler that allows for the drug to be combined in such a way as to be formed into a pill. Liquid capsules allow for rapid release of the liquid drug mixture in the small intestine. Some pills are formulated so that they are able to release compound over the course of several hours, an example of this is 12–24-hour release decongestants and the list goes on. Small molecule drugs have had wide success in becoming oral medications, but other larger molecules such as antibodies or genetic material are more difficult to get through the digestive system and liver intact so these may require alternative methods of delivery or modifications to allow for use in an enteral route.2
The ability to evaluate compound suitability for various modes of administration is a very important part of the drug discovery process. Visikol services incorporate many human in vitro models which can be used to evaluate a drug’s absorption through various tissues, potential toxicity, and metabolism. These services use both models developed by their BICO sister company MatTek, as well as in-house models.