Evaluation of a compounding phospholipid base for the percutaneous absorption of high molecular weight drugs using the Franz finite dose model

BACKGROUND

Permeation-enhancing compounding bases are aimed to facilitate the penetration of the active pharmaceutical ingredients (APIs) across the skin barrier.

OBJECTIVES

The purpose of this study was to evaluate the percutaneous absorption of radiolabeled human insulin (14 C-isototpe) when incorporated in a proprietary phospholipid base designed to deliver APIs with high molecular weights (HMW). The aim was not to claim the transdermal delivery of insulin with potential therapeutic applications in diabetes but, instead, to evaluate the ability of the compounding phospholipid base to deliver HMW drugs.

METHODS

The percutaneous absorption of 14 C-insulin was determined using human torso skin and the Franz skin finite dose model. Two topical test formulations were prepared for in vitro evaluation: insulin 1% in phospholipid base (standard) and insulin 1% in phospholipid base HMW. The rate of percutaneous absorption (mean flux) and the distribution of 14 C-insulin through the skin were evaluated for both topical test formulations. A two-way ANOVA was used to determine statistical differences.

RESULTS

The 14 C-insulin was distributed into the stratum corneum, epidermis and dermis. Mean flux values showed a rapid penetration upon application and the maximum flux was achieved at 30 min, followed by a slow decline. Subsequently, a slower decline was observed for the topical test formulation including the phospholipid base HMW.

CONCLUSION

The phospholipid base HMW facilitates the percutaneous absorption of HMW drugs across human cadaver skin and, therefore, it may potentially be a useful option for compounding pharmacists and practitioners when considering the skin for the percutaneous delivery of large drugs.

Characterization of the Percutaneous Absorption of Ketoprofen Using the Franz Skin Finite Dose Model

OBJECTIVES

Ketoprofen is an analgesic, anti-inflammatory agent commonly used in the management of chronic musculoskeletal pain. The aim of this study is to characterize the percutaneous absorption of 2 ketoprofen formulations (ketoprofen 10% in Pluronic Lecithin Organogel (PLO) and ketoprofen 10% in Lipoderm, referred to as phospholipid base), when applied to the human cadaver trunk skin, in vitro, using the Franz skin finite dose model. PLO and phospholipid base are vehicles used to facilitate the delivery of drugs into and through the skin following topical applications.

METHODS

The percutaneous absorption of ketoprofen was evaluated using human cadaver trunk skin from 3 donors. The skin was cut into small sections and cultured within Franz diffusion cells. A variable finite dose of each formulation was then applied to 3 replicate skin sections per donor and receptor solutions were collected at predetermined time points (0, 4, 8, 12, 24, 32, and 48 hr). After the last receptor sample was collected, skin surfaces were washed and split into epidermis and dermis. Collected samples were analyzed using HPLC.

RESULTS

Both PLO and phospholipid base were capable of facilitating the absorption of ketoprofen across human cadaver trunk skin. However, ketoprofen, when in phospholipid base, showed higher mean total absorption (p = 0.022) and faster rate of absorption (p < 0.05 at 2, 6, 10, and 18 hr) than when in PLO.

CONCLUSION

Chronic musculoskeletal pain can be a major burden for most patients, affecting their lifestyle and reducing overall quality of life. When compared to PLO, phospholipid base has the ability to potentially deliver higher concentrations of ketoprofen to underlying soft tissues and at a more rapid rate. With more ketoprofen at the site of injury, the analgesic and anti-inflammatory effects will likely be enhanced, potentially reducing pain and improving quality of life.