Current innovations in drug delivery.
It is almost twenty years since the attention of the pharmaceutical industry was focussed on an alternative strategy--improving existing medicines by better control of the site, duration and intensity of the drugs they contain. Whilst site specificity remains a major objective for future medicines, progress has mainly come from devices which modulate the duration and intensity of drug action. In their most advanced form, they will deliver their contents in response to a physiological or pathological demand such as a diabetic's glucose level. However, practical devices have been limited to passive dosage forms which either speed up or slow down the rate of systemic absorption in a controlled manner. Oral, rectal, percutaneous and parenteral routes have been energetically explored and several products have been successfully marketed. Oral administration has dominated invention. Future advances will embrace the concepts of variable or pulsed release in order to meet particular therapeutic criteria. Equally important will be the extension of transit time in order to increase the uptake of some poorly absorbed drugs, or to extend dosage intervals to twenty-four hours. Attempts to more closely approach constant release rates at the end of the release period, to devise efficient formulae which carry drug loadings in excess of eighty per cent, or to invent formulae which, whilst retaining precision, are cheaper and more easily manufactured are less innovative aspects of this important field. The commercial success of percutaneous presentation of glyceryl trinitrate has prompted further refinement of this principle and guidelines for exploitation are now clearer. The development of acceptable penetration enhancers remains an important element in extending this principle to a wide range of drugs.(ABSTRACT TRUNCATED AT 250 WORDS)
Ganderton
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Chelsea Department of Pharmacy, King's College London, UK.
D000279:Administration, Cutaneous; D000284:Administration, Oral; D004333:Drug Administration Routes; D006801:Humans; D007263:Infusions, Parenteral