GSP 304 (Tiotropium Bromide)

GSP 304 (tiotropium bromide) is a mist that Glenmark Pharmaceuticals is developing to widen the narrowed airways that are a hallmark of chronic obstructive pulmonary disease.

Glenmark is working on U.S. Food and Drug Administration approval of GSP 304 as a COPD maintenance therapy. A key step was completing a Phase 2 clinical trial (NCT03118765) of the mist as a treatment for the airway condition, known as bronchospasm.

How GSP 304 works

GSP 304 is a tiotropium bromide solution that Glenmark delivers as a mist. The FDA has already approved inhaled powder and spray versions of it. The powder version is Spiriva HandiHaler and the spray version Spiriva Respimat.

Tiotropium bromide is a bronchodilator, or substance that relaxes airway muscles so they can widen. Widening air passages to the lungs allows COPD patients to breathe easier. GSP 304 prevents patients’ wheezing, shortness of breath, coughing, and chest tightness.

When cell surface proteins known as acetylcholine receptors bind with the nerve cell signaling transmitter acetylcholine, airway muscles contract, making breathing more difficult. GSP 304, a muscarinic receptor antagonist, prevents the binding, relaxing airway muscles. The result is wider passages to the lungs and easier breathing.

GSP 304 in clinical trials

Key objectives of the Phase 2 trial that Glenmark completed this year included seeing how safe GSP 304 was and looking at its pharmacodynamics, or effect on the body, and pharmacokinetics, or movement through the body. Another important objective was to see which of three doses of  the therapy was the best to be tested in a Phase 3 trial.

About 155 people, ages 40 to 85, participated in the three-week trial. The study began in March of 2017 and was completed in July. Glenmark has yet to release the results.


COPD News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.