Who Invented Metered Dose Inhalers?

Inhalers are essential for many people across the world. But do you know who invented the first convenient, portable and effective inhaler for managing asthma? National Inventors Hall of Fame^® Inductees George Maison, Irving Porush and Charles Thiel invented the first pressurized metered dose inhaler (MDI). Introduced in 1956, the MDI has saved lives and improved the quality of life for hundreds of millions of people.

Get to Know the Inventors

Maison was born in Frankfort, Kentucky, in 1911. He studied physiology at Northwestern University, earning his bachelor’s degree in 1930, his master’s degree in 1934 and his medical doctorate in 1935. During World War II, Maison served in the U.S. Army Air Forces and was chief of a unit in the air technical service command's engineering division. He received the Legion of Merit in 1945 for his work in perfecting the anti-G suit worn by fighter pilots to prevent blackout when pulling out of a dive.

Porush was born in Newark, New Jersey, in 1917. He earned his bachelor’s degree in chemistry from UCLA in 1939 and his master’s degree in meteorology from the California Institute of Technology in 1941. Porush also served in the U.S. Army Air Forces. He was a weather officer, providing weather information to pilots who were ferrying bombers across the Atlantic Ocean for the British during World War II. He received commendations from the Secretaries of Commerce and War for providing timely hurricane information that saved lives and minimized the loss of property in 1944.

Thiel was born in Santa Barbara, California, in 1928. He served in the U.S. Army Air Forces as a military photographer and was stationed in Japan. At the University of California, Santa Barbara, he earned his bachelor’s degree in chemistry in 1954.

The Question That Sparked an Invention

The inspiration for the invention of the MDI came from a conversation between Maison and his 13-year-old daughter Susie Maison. Susie had asthma, and the nebulizer she depended on was rather difficult to handle. Like many nebulizers available at the time, it had a fragile squeeze bulb that was not easy to use, so there was a significant need for an easier, more user-friendly solution.

Susie asked her father if asthma medication could be delivered in a spray, like aerosol cans of hairspray. Maison was intrigued and immediately began to explore the possibilities.

Maison had become president of Riker Laboratories, a subsidiary of Rexall Drug Co., in 1953, and he brought his daughter’s question to the Riker team. He first collaborated with Porush, who was the company’s head chemist. Porush consulted with Rexall’s cosmetics laboratory, which provided him information about aerosol equipment, propellants and supplies.

Soon, Porush had developed an MDI prototype using soda bottles and chlorofluorocarbon refrigerants, and he formulated solutions using epinephrine or isoproterenol. These are fast-acting medications that open the airways and help patients with asthma to more easily breathe.

Thiel, another chemist at Riker, took on the challenge of ensuring that the medication could be delivered effectively in the form of a spray. He created an innovative suspension of the medication in a liquefied gas propellant, which increased the amount of the drug that would be delivered to the patient’s lungs.

Maison, Porush and Thiel’s finished device included a reservoir with a mixture of medication and liquefied gas propellant; a metering valve for delivering a specific amount of the reservoir’s contents; and a spray actuator to control atomization of the drug. When the valve was pressed, the metered dose of the drug would flow into the valve stem. At the spray actuator, it was atomized and released as a fine aerosol plume.

Providing Fast, Reliable Relief

The MDI was tested for safety in June 1955, and in early 1956, clinical research showed the majority of patients experienced excellent symptom relief. It was approved by the Food and Drug Administration in March 1956, making it the first device of is kind to receive approval for use by asthma patients.

Riker Laboratories marketed the MDI as the Medihaler. Its small, portable design revolutionized asthma management, providing nearly instant relief from respiratory distress in an easy-to-use, highly effective system.

In 2014, it was reported that more than 2,000 people were taking doses from an MDI every second. In 2020, in the U.S. alone, an estimated 144 million MDIs were sold, and in 2021, the global MDI industry was valued at $16.3 billion. This is expected to increase to $22.1 billion by 2031.

Meet More Icons of Invention

Nearly 700 inventors have been inducted into the National Inventors Hall of Fame. To learn more of their stories, keep exploring our website. To tell us who should become the next Inductee, make a nomination!