Dura Pharmaceuticals issued patent for dry powder inhalation delivery

Covering delivery system and particle technologies

Dura Pharmaceuticals Inc. (San Diego) has been issued U.S. Patent 6,116,237, covering methods of dry powder inhalation. The patent claims include inhaler design, as well as drug particle and aerodynamic sizes, which result in improved inhalation delivery profiles. The patent describes inhaler resistances, considered important for allowing patients to operate powder inhalers for a range of drug particle sizes over flow rates from 15 to 60 liters per minute. Dura believes that drawing up the patent in this manner provides them and their collaborators with extensive protection.

According to Dura, when applied to insulin and other systemically targeted macromolecules, their inhaler design lung deposition. Drugs normally delivered intramuscularly, such as vaccines, antibiotics, and respiratory compounds will also benefit from larger particle aerodynamic sizes, which are more efficiently delivered to the upper airways. The issued patent is not specific to a drug, formulation, or inhaler and can be used with or without energy-assisted mechanisms to aid in powder dispersion, such as Dura's Spiros blisterdisk system and its motorless Spiros S2 system.

Dura is currently developing, with Eli Lilly and Co. (Indianapolis), a method of inhaled insulin delivery using the motorized Spiros blisterdisk drug delivery system. Dura also intends, through partnerships, to develop the Spiros motorized blisterdisk and Spiros S2 pulmonary drug delivery systems. Spiros S2 has potential for use with proteins and peptides.

Business strategy
In its approach to novel delivery systems, Dura is banking on two favorable factors: Markets for large-molecule drugs are growing fast; metered dose inhalers, the principal inhalation technology in use today, may be on its way out.

According to figures from Dura, the worldwide market for peptide and protein drugs totaled $13 billion in 1997 and may grow to $24 billion by 2002. Optimism for inhaled compounds is based on the need for more large-molecule drugs (including genes, peptides, and proteins), and the lack of a systemic delivery system that can compete with injection.

Dura is not alone in its belief that believes that dry powder inhalers (DPIs) will eventually replace MDIs as the leading pulmonary delivery system. The reasons:

• MDIs generally use ozone-depleting chloroflourocarbon (CFC) propellants, which are being phased out by international agreement, to make the drug spray out when the inhaler is actuated. The FDA and EPA have granted current inhaler technology a temporary exemption from the ban until adequate alternative delivery systems have been developed and approved.
  
• MDI technology suffers from compliance issues because they are difficult to use. To receive an accurate dosage, patients must coordinate their breathing with inhaler actuation, a balancing act that up to 80% of patients cannot manage.
  
• DPIs are already popular in Europe, where they have been available for many years. U.S. market preferences could follow a similar pattern.

For more information: Lloyd Flanders, Senior Vice President for Technology Operations, Dura Pharmaceuticals Inc., 7475 Lusk Blvd., San Diego, CA 92121. Tel: 858-457-2553.

Edited by Angelo DePalma
Managing Editor, Drug Discovery Online and Pharmaceutical Online
Email: adepalma@vertical.net