budesonide
Meaning of budesonide: Its usefulness rests less on potency than on delivery, since the liver destroys most of a swallowed dose before it reaches the wider body.
Definition of budesonide
Budesonide is a corticosteroid used to calm inflammation, most often in asthma, allergic rhinitis and inflammatory bowel disease. It mimics cortisol, the hormone made by the adrenal glands, switching off the genes that drive an inflammatory response. It is formulated to act where it is applied, so inhalers, nasal sprays, capsules and rectal preparations all deliver it locally.
How does it work?
Budesonide is a glucocorticoid, the same family of signal as cortisol released by the adrenal gland. It passes into a cell, binds a receptor waiting in the cytoplasm, and the pair travels to the nucleus, where it turns down the genes that manufacture inflammatory messengers and turns up those that restrain them. That is a slow lever. Meaningful benefit takes hours to days and full effect takes longer, which is why an inhaled corticosteroid is a controller rather than a reliever and does nothing for a sudden attack of breathlessness.
Why does the delivery form matter?
| Form | Where it acts | Used for |
|---|---|---|
| Inhaler | Airway lining | Long-term control of asthma |
| Nasal spray | Nasal lining | Allergic rhinitis and nasal polyps |
| Controlled-release capsule | End of the small intestine and right colon | Crohn disease, microscopic colitis |
| Rectal foam or enema | Rectum and left colon | Ulcerative colitis affecting the lower bowel |
What makes this possible is chemistry rather than clever packaging. Budesonide is broken down heavily by the liver on its first pass, so most of what is swallowed or absorbed from the gut never reaches the general circulation. The drug does its work at the surface it touches and is then largely dismantled, which keeps whole-body exposure lower than an equivalent dose of an oral steroid such as prednisone.
What effects are known?
Local effects follow the route. An inhaler can cause hoarseness and thrush in the mouth, since a proportion of every puff lands there rather than in the airways. Nasal spray can cause dryness, irritation and occasional nosebleeds. Whole-body corticosteroid effects are less likely than with oral steroids but not abolished: at higher doses, over long periods, or when combined with medicines that block the liver enzyme responsible for clearing it, budesonide can suppress the body's own cortisol production and contribute to bone thinning, raised blood sugar, cataract and, in children, a slowing of growth.
Also known as
Used in a sentence
An inhaled corticosteroid, budesonide, was prescribed for ongoing control of the patient's asthma.
Good to know
Inhaled and nasal budesonide act mainly at the surface they reach and are largely broken down by the liver before entering the general circulation, which separates their pattern of effects from an oral corticosteroid taken for widespread inflammation.