Newer techniques of drug delivery:

Encapsulation Matrices: The action of rapidly cleared drugs can be prolonged by incorporating them in a variety of encapsulation matrices including liposomes, iophendylate and polyanhydride polysomes.

Liposomes: Liposomes are reservoirs containing an aqueous phase surrounded by phospholipid bilayers. Liposomes encapsulation permits the delivery of relatively large concentrations of a drug in the form that is sequestered and slowly released into the local biophase. This exposes the local tissues to relatively steady state concentration of the drug over an extended period by reducing the bio-availability, so high dose effects (respiratory depression) or high dose tissue toxicity may be reduced.

Iophendylate: In rabbits, placing LA in iophendylate prolongs their spinal action.

Transfersomes: A new type of analgesic drug carriers the transfersome, can penetrate rapidly down hydration gradient through the intact dermis and reach cutis and subcutis, thus affecting the nociceptors and mainly vesicular patches. Each transfersomes consists of atleast one inner aqueous compartment. This is surrounded by a lipid bilayer. Transfersomal drug carriers can accommodate hydrophilic drugs or lipophilic drugs.

Microspheres: Encapsulating bupivacaine in poly (D,L)-lactide-co-glycolide microspheres prolongs analgesia and diminishes systemic toxicity.

Spinal implants:

Drug delivery systems can be categorized as follows:-
During patient selection, the general and mental status, life expectancy, nature and the origin of the pain, skin over the implantation area, patients environment and support systems should be considered.

Contra-indications: Include patient refusal, cachexia, sepsis and concomitant anticoagulant therapy.