Microneedles: the next step in transdermal drug delivery?

microneedles-pennyHelen Quinn is a pharmacist and PhD student at Queen’s University Belfast.

Pharmaceutical research in a laboratory and clinical practice may sometimes feel like worlds apart but it is my belief that the best informants of research are those who are actually involved in caring for the patient.  This should be the principal motivation behind any research. My PhD project is based on the use of microneedles, an innovative form of transdermal drug delivery, which is rapidly gathering pace towards commercialisation. In an industry traditionally focussed on the discovery of new drugs, a new method for delivery of medication is long awaited to challenge the accepted routes of oral and parenteral delivery, which although suitable for the majority, are not without their drawbacks, particularly in the geriatric patient.

Transdermal delivery has a number of advantages due to its patient-friendly and convenient nature, but its capabilities have reached their limit with less than 20 different drugs available in patch form. In recent years, attention has therefore shifted to methods of enhancing the skin permeability to allow more medication to be delivered in this way. Microneedles were borne out of this line of thinking and although, the first patent was filed in the 1970s, manufacturing advances only allowed the first microneedles to be made in 1998.

What are microneedles?

microneedles-microscopeMicroneedles consist of a number of tiny projections, up to a maximum of 1 mm in length, arranged on a supporting base to form a patch. When pressed onto the skin, the tiny needles penetrate and cross the outermost layer, creating micropores, which allow drug delivery to the deeper skin layers and microcirculation, followed by subsequent transport to the systemic circulation. Due to their small size, the process of application is painless and blood-free. It has been likened to the sensation of Velcro® or a cat’s tongue when applied.

Microneedles have been manufactured worldwide from a variety of materials including silicon and metal. In our research group at Queen’s University Belfast, microneedles are prepared from a safe, biocompatible polymer. When inserted into the skin, the microneedles take up interstitial fluid and swell, allowing control of the rate of delivery from a separate drug reservoir. When removed, the needles are softened so cannot be reinserted into another patient, reducing the risk of transmission of infection and eliminating the possibility of a needlestick injury.

Microneedles have been investigated for delivery of a wide range of medication, from those traditionally given as tablets or capsules such as metronidazole and theophylline to injectables such as insulin and the influenza vaccine, demonstrating their potential for a number of applications.

microneedles-handWith the increasing number of older people in our society, alongside the high medication consumption of this group, it is envisaged that older people may be one of the principal users of microneedle technology in the future. Transdermal delivery also has a number of pertinent advantages in the older population, particularly those suffering from dysphagia or with limited venous access. To investigate how acceptable and potentially useful microneedles may be for older people, we are interested in your views and opinions. We have created a short online questionnaire for those with an interest in geriatric medicine to complete to inform our continuing research for this population. If you are willing to participate, please follow the link below. The questionnaire will take approximately 10 minutes to complete. Your input is much appreciated!


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