Drug inhalation technologyRespiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD), are on the increase due to a combination of factors which include tobacco use (particularly increased use among women), air pollution and inhalation of substances which can irritate the airways, such as dusts and chemicals.

Across the world, the World Health Organisation (WHO) estimates the number of asthma sufferers at around 300 million. Asthma is the most common chronic disease among children. According to the latest WHO figures, an estimated 210 million people have COPD, worldwide. Neither of these diseases is curable, but treatment can help control symptoms and increase quality of life for sufferers. The global market for asthma and COPD treatments was estimated as almost $20 billion in 2007.

Inhaled pharmaceuticals 

Advances in drug formulation have made pulmonary delivery products increasingly feasible and commercially viable, leading to improvements in the treatment of asthma, COPD and other respiratory diseases. Drugs delivered through an inhaler go directly into the airways when the patient breathes in. This means a smaller dose is needed than if the drug were administered orally. For respiratory diseases, the drug is administered directly at the site of the disease. Little of the drug gets into the rest of the body, so side effects are unlikely to occur.

The challenges

There are a number of challenges to overcome in the successful development and commercialisation of an inhaled pharmaceutical. The lungs are a very effective mechanism for keeping foreign particles out of the body, and the size of the drug particle is a critical element. Anything larger than 10µm (or 10 thousandths of a millimetre) will be swallowed and will never reach the lungs. Anything smaller than 1µm will be blown back out of the mouth when the person exhales. This leaves a very narrow particle size range, between about 2 and 5µm, as optimal for the deposition of a drug into the lungs. However, very small particles will adhere together to form agglomerates much larger than the critical 5µm in size.

Overcoming particle adhesion

In the 1990s, research within the field of particle engineering and powder technology at the Centre for Drug Formulation Studies at the University of Bath resulted in significant progress in overcoming the issue of drug-drug particle adhesion. This was achieved by the inclusion of pharmacologically inactive materials within the formulation to modify how individual drug particles interact, thereby optimising the proportion of the drug reaching the lungs. Old- style inhalers prescribed to asthma sufferers delivered approximately 20% of the dose effectively to the respiratory tract. However, the exact amount delivered on each occasion could be highly variable. Improvements to the interactions between the drug particles and the inert carrier particles mean that around 50% of the dose is now delivered, on a consistent basis.

Vectura Group plc

Vectura Group plc originated from this research into the delivery of drugs via the respiratory system. Ventura is a product development company focused on the development of pulmonary products using its proprietary inhaler device and formulation technologies. The company has eight products marketed by its partners and a portfolio of drugs in clinical and pre-clinical development, some of which have been licensed to major pharmaceutical companies. Vectura also offers its formulation and inhalation technologies to other pharmaceutical companies on a licensing basis. The company is listed on the London Stock Exchange with sites in the UK and a small office in the United States. Vectura continues to benefit from its technological skills and intellectual property, and in July 2010, signed a dry powder formulation licensing deal with GlaxoSmithKline worth £20 million in up-front and milestone payments, as well as royalties on product sales.

Improved understanding of asthma has lead to enhanced treatment regimens for sufferers. These have been complemented by improvements in inhaled pharmaceutical products such as those developed by the team at the University of Bath and Vectura.

 

The future

Some of the original research team are now back at the University of Bath working for Swedish pharmaceutical company, Orexo, after their spin-out PharmaKodex was acquired by the Swedish firm in 2009. The main focus of their new work is in transdermal and topical drug delivery. They are developing a novel tablet which delivers a metered dose of a drug when applied to the skin via an applicator and gentle rubbing. This provides a less messy and more accurate way of administering drugs than creams or ointments.