What is the Origin of Subcutaneous Pellet Implants?

The concept of subcutaneous implantation for drug delivery dates back to the early 20th century, with the use of crystalline hormone pellets. The term is descriptive, combining "subcutaneous," referring to the anatomical layer beneath the dermis, with "pellet implants," describing the solid dosage form and method of administration. Modern technology has refined the composition and manufacturing of these pellets for more predictable release kinetics.

What is the Mechanism of Subcutaneous Pellet Implants?

The mechanism of drug release is primarily through dissolution and diffusion from the solid matrix into the surrounding adipose tissue fluid, followed by systemic absorption via the local capillaries. The slow, constant dissolution rate is governed by the pellet's surface area and the density of the compressed material. This diffusion-controlled process ensures a stable, zero-order release profile, maintaining therapeutic hormone levels without the peaks and troughs seen with daily or weekly dosing.

Subcutaneous Pellet Implants

Meaning

Subcutaneous pellet implants are a form of long-acting drug delivery system where solid, compressed cylinders of a hormone or therapeutic agent are surgically inserted into the fatty tissue beneath the skin. This method provides a steady, continuous release of the active compound over several months, offering a highly consistent and physiological level of hormone replacement. Clinically, this approach bypasses the gastrointestinal and hepatic metabolism associated with oral dosing, leading to stable serum concentrations and improved patient adherence. The use of these implants is common in personalized hormone therapy for both men and women.