An overview of drug delivery technologies

Drug delivery systems (DDS) are a strategic tool for expanding markets/indications, extending product life cycles and generating opportunities. DDS make a significant contribution to global pharmaceutical sales through market segmentation, and are moving rapidly, from traditional oral and transdermal delivery of new chemical entities (NCE), to more advanced non-invasive delivery of proteins and peptides.

This overview is intended for those involved in non-instrumental drug delivery systems in which a drug is contained, or presented in a special formulation that modifies its absorption characteristics.

There has been continuous growth in the area, although some 25 DDS products, mainly oral, account for world-wide sales of US$11.5 billion per annum. This growth is not only of strategic importance for market advantage over competitors; drug delivery technologies also offer product patent extension and improved efficacy or targeted delivery of drug.

Drug delivery systems play an important role in developing successful pharmaceutical products. They:

1. enable a drug to be presented to a patient in a manner that makes it acceptable to them and allows the drug to be effective;

2. widen the population of patients who are able to use a drug;

3. increase the range of indications that a drug can be used to treat;

4. improve the performance of a drug;

5. are also used as marketing tool to attract users of the drug.

Drug delivery technology plays a key role that is particular for each class of drug.

Current drug delivery systems include steady state release, pulsed drug delivery, injection free, subcutaneous, suppository, autoinjection and targeted delivery systems, offering benefits of improved drug absorption, reduced compliance issues, prolonged effect, and minimised side effects.

An example is the Subcutaneous Autoinjector (Imigran, Glaxo product) which has key characteristics of:

• fast onset of action;

• high bioavailability;

• automated injection;

• patient compliance.

Other drug delivery systems include:

Suppository systems, providing

• good onset of action;

• convenience;

• market/population specific.

Intranasal spray systems, providing

• fast onset of action;

• high bioavailability;

• convenient.

Nasal systems have the potential to act as a conduit for delivering drugs to the brain. The olfactory system provides a direct link to the brain, therefore bypassing the blood brain barrier. This could result in Alzheimer’s and other neurodegenerative disorders being treated in this manner.

Inhalation technology offers aqueous aerosol droplets containing liposomes as slow release carriers has been employed. The technology is designed to avoid the convoluted branching of the bronchial tree and wafts most of the aerosol into absorbent alveoli. The technology is said to avoid the bronchioles and ciliary clearance, and delivers the aerosol to deep lung for sustained release.

Inhalation systems also include dry powder technology platforms and pulmonary delivery of macromolecules.

Fast dissolving technology offers

• improved compliance/added convenience;

• no water needed;

• no chewing needed;

• better taste;

• improved stability;

• suitable for controlled/sustained release actives.

This technology has attributes/value added benefits which include improved oral absorption, faster onset of action and avoids the first pass effect. The technology also has significance in dysphagia – 35% of the population have difficulty in swallowing, based on dysphagia prevalence of swallowing complaints and clinical findings, 30-40% of elderly nursing home patients and 25-50% of patients hospitalised for acute neurological disorders and head injuries (according to Dysphagia, Aging and Esophagus report).