ABSTRACT
Delivery of topical acne medications has focused on two challenges during the past decade. First, delivering the drug to the pilosebaceous unit (PSU) is required for treating diseases such as acne that have their origin in that unit. The other challenge is delivering medications such as exfoliating agents via controlled release systems that keep the irritation caused by these drugs in abeyance. Follicular delivery involves depositing drugs in the hair follicle, hair shaft, sebaceous glands, and all components of the PSU. It is hypothesized that vehicles, which are miscible with sebum, may help the active ingredient concentrate preferentially in the PSU. Such a preferential accumulation can be advantageous for increasing the transport of the drugs through the skin, as well as for targeting the drug to achieve therapeutic efficacy in the PSU itself. Knowledge of sebum lipid components helps us to consider how a penetrating vehicle will react upon entrance into the follicular canal. Additionally, these systems must release drugs into the follicle slowly over time, as well as target their delivery into the epidermis in the follicle via partitioning from slow release agents and mild vehicles so that the system is non-irritating. The major goals of this chapter are:
1. To review methods/models used to study penetration of and actions of ingredients within the PSU,
2. To review the fundamental research on technologies that target drugs to the PSU,
3. To review investigations of different vehicle effects on the thermal behavior of model sebum and their role in targeting delivery of acne medications to the PSU, and
4. To discuss recent advances in new drug delivery technologies in marketed or newly developed topical acne treatments.
