A 3D printed ballistic drug delivery system for wildlife administration
Overpopulation of wildlife, especially in pest-prone territories, is a major ecological problem. Culling is the most effective population control approach but drug-induced contraception is also common for protected species. The administration of contraception in the wild has been restricted to conventional methods such as surgery which require capturing and handling often large numbers of incorporative or dangerous animals. This thesis proposed a new approach for wildlife contraception by utilising three-dimensional (3D) printing technology to fabricate a novel ballistic drug delivery system (BDDS) capable of remotely administering contraceptives amongst any other required drug(s). A literature review was conducted focusing on the use and application of fused deposition modelling (FDM) method of 3D printing in drug delivery (Chapter 2). In chapter 3, A ballistic projectile for short-term (seasonal) progesterone (P4)-induced contraception was developed using FDM. A sustained drug release (over five months) was achieved with the projectile providing sufficient kinetic energy to penetrate thin and medium-thickness skins. Subsequently, this projectile was modified to a multi-compartment model capable of loading and delivering multiple drugs, including anti-inflammatory dexamethasone (DEX), local anaesthetic lidocaine hydrochloride (LDC) and contraceptive levonorgestrel (LNG). The drug formulations were independently developed in the following chapters: DEX was formulated in poly (vinyl alcohol) (PVA) hydrogels, and a sustained release was achieved over one month (Chapter 4), LDC was incorporated with chitosan-pectin (CS-PEC) hydrogel and manufactured as a customised 3D printed wound dressing that released LDC in 5h (Chapter 5), LNG was incorporated within a combined system of CS microspheres and PVA hydrogels, achieving controlled release for over two years (Chapter 6). The above formulations, can be easily incorporated into a multiple-compartment projectile as a BDDS or could be used individually for other clinical applications. The new knowledge created by this thesis provide new insights into ballistic delivery to wildlife, and make a major contribution to advance the application of 3D printing technology in drug delivery.