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DRUG DELIVERY
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Key Targeting Approaches for Pharmaceutical Drug Delivery
Dev Prasad1 Harsh Chauhan, Ph.D.2
1Massachusetts College of Pharmacy and Health Sciences 2Creighton University
Drug targeting is defined as the ability of a drug molecule to accumulate in the target organ or tissue selectively such that the concentration of the drug at the disease site is high, while its concentration in non- target organs and tissues is low, preferably, below certain minimal level so as to prevent any toxic effect. Thus, drug targeting can overcome the non-specific toxic effect of conventional drug delivery. This may also reduce the amount of drug required to dose. A drug can be targeted on the level of a whole organ, on the level of certain cells specific for a given organ, or even on the sub-cellular level of specific tissue [1]. The concept of drug targeting was first mentioned by Paul Ehrlich when he suggested the hypothetical “magic bullet” as an entity consisting of two components — the first one should recognize and bind the target, while the second should provide a therapeutic action in this target. Currently, the concept of ‘magic bullet’ includes a coordinated behavior of three components – drug, targeting moiety and pharmaceutical carrier [2].
Various pharmaceutical carriers explored for targeting drug include polymeric micelles, liposomes, nanoparticles such as solid lipid nanoparticles, gold nanoparticles, quantum dots, etc. All these carriers can be made targeted in one way or another. The most widely-used approach involves utilizing specific targeting moieties. However in certain cases, physical principles or some physiological features of the target area may be utilized for a successful targeting of pharmaceuticals and pharmaceutical carriers. [1-3]
This article highlights approaches for drug targeting. Direct Application
Direct application of a drug into the affected area qualifies as a drug targeting approach as a high concentration of drug is achieved in the target area. Direct application may sound like a simple technique to achieve drug targeting, however developing such formulations can be complicated. The successful example of this approach includes intra-articulate administration of methotrexate liposomal preparations containing a phospholipid conjugate of methotrexate and dimyristoylphosphatidylethanolamine (MTX-γ-DMPE) for the treatment of arthritis [4]. Ophthalmic delivery of carteolol loaded
64 | | September/October 2013 - 15TH ANNIVERSARY ISSUE
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