The inhaler is a device that delivers medication directly into the lungs, providing rapid relief and targeted treatment for respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). This delivery method allows smaller doses to be effective while minimizing systemic side effects. Inhalation therapy spans thousands of years, evolving from simple herbal fumes to the sophisticated, pocket-sized devices used today, reflecting a consistent effort to efficiently deliver medicine to the respiratory system.
Early History of Therapeutic Inhalation
The concept of therapeutic inhalation dates back over 3,500 years to ancient civilizations. The Ebers Papyrus, an ancient Egyptian medical text from approximately 1554 BC, describes treating breathing difficulties by instructing patients to inhale vapor created by placing plants like black henbane onto hot bricks. Ancient Indian Ayurvedic texts and Greek physicians, such as Hippocrates and Galen, also documented methods for inhaling medicated steam or fumes. The burning of specific herbs or resins, such as stramonium leaves, was a common practice for asthma relief well into the 19th and early 20th centuries. These practices established the fundamental principle that compounds could be delivered directly to the lungs to treat respiratory ailments, focusing on the medicine and the method of producing fumes rather than mechanical devices.
The First Mechanical Devices
The first true mechanical devices for inhalation appeared in the 18th century, marking a shift from simple steam pots and burning herbs. In 1778, English physician John Mudge invented a pewter device, known as the Mudge Inhaler. This device was a pewter tankard with a valve-controlled mouthpiece, allowing the user to inhale air bubbled through a medicated liquid. The mid-19th century brought the development of nebulizers, which atomized liquid medication into a fine spray. In 1858, French physician Sales-Girons created one of the first powered nebulizers, using a pump handle to push liquid through an atomizer. In 1864, Emil Siegle in Germany developed a steam-spray inhaler that utilized steam from boiling water to draw medication out of a separate chamber for inhalation. These early atomizers and nebulizers, often bulky, tabletop instruments, paved the way for the use of liquid solutions, such as early epinephrine formulations, to treat asthma more effectively.
The Invention of the Metered-Dose Inhaler
The single most significant invention that created the modern inhaler occurred in the mid-1950s, dramatically changing respiratory care. In 1955, Riker Laboratories (later 3M) began development of the Metered-Dose Inhaler (MDI). The MDI represented a convergence of two new technologies: the use of liquefied gas propellants, such as chlorofluorocarbons (CFCs), and a new metering valve originally designed for perfume bottles. This combination allowed for the precise delivery of a small, aerosolized dose of medication in a highly portable, pocket-sized canister. Following rapid development, Riker Laboratories launched the first two MDI-based products, Medihaler-Epi (epinephrine) and Medihaler-Iso (isoproterenol), in March 1956. This breakthrough device made it possible for patients to carry their asthma treatment easily, providing quick and consistent doses of medication outside of a clinical setting for the first time.
Modern Inhalation Delivery Systems
The success of the MDI spurred the development of diverse modern inhalation delivery systems, each designed to optimize drug delivery to the lungs. The MDI remains a widely used system, functioning by using a pressurized propellant to release a specific, metered volume of medication upon actuation. Since the 1990s, the original CFC propellants have been replaced with more environmentally friendly hydrofluoroalkane (HFA) propellants. Another widely used system is the Dry Powder Inhaler (DPI), which delivers medication as a fine powder rather than a pressurized aerosol. DPIs are breath-actuated, meaning the patient’s own rapid inhalation creates the airflow turbulence necessary to disperse the micronized drug particles from a carrier substance, such as lactose. Because they do not use a propellant, DPIs eliminate the need for coordinating actuation and inhalation, a common challenge with MDIs. Modern nebulizers have also evolved, moving beyond the bulky 19th-century models to use ultrasonic waves or vibrating mesh technology to create a fine, breathable mist from liquid medication. These devices allow for the administration of large doses and are especially useful for very young children or patients who cannot use other inhaler types due to poor coordination or severe symptoms.