From the Guidelines
Dexamethasone is faster acting than prednisolone.
Comparison of Corticosteroids
- The choice between prednisolone and dexamethasone depends on the desired rapidity of response, with dexamethasone showing a faster increase in platelet count at 7 days 1.
- According to the American Society of Hematology 2019 guidelines, dexamethasone (40 mg per day for 4 days) may be preferred over prednisone (0.5-2.0 mg/kg per day) for initial therapy in adults with newly diagnosed ITP if a rapid response is desired 1.
- The conditional recommendation is based on very low certainty in the evidence of effects, but dexamethasone has shown increased desirable effects with regards to response at 7 days, making it a faster acting option 1.
From the FDA Drug Label
Dexamethasone sodium phosphate injection has a rapid onset but short duration of action when compared with less soluble preparations. Prednisolone is rapidly and well absorbed from the gastrointestinal tract following oral administration. Prednisolone sodium phosphate oral solution produces a 14% higher peak plasma level of prednisolone which occurs 20% faster than that seen with tablets.
Based on the information provided, dexamethasone is described as having a rapid onset of action, while prednisolone is also rapidly absorbed. However, the exact comparison of their onset of action is not directly stated.
- Dexamethasone has a rapid onset, but the duration of action is short.
- Prednisolone is rapidly absorbed, with a peak plasma level occurring 20% faster with the oral solution compared to tablets. Since the FDA label does not directly compare the two, no conclusion can be drawn about which is faster acting. 2 3
From the Research
Comparison of Prednisolone and Dexamethasone
- The effectiveness of prednisolone and dexamethasone has been compared in several studies 4, 5, 6.
- A study published in the Journal of family medicine and primary care found that oral dexamethasone had a faster action and minimal side effects compared to oral prednisolone in the management of acute exacerbation of asthma 4.
- Another study published in the European journal of hospital pharmacy found that single-dose dexamethasone was at least as effective as a 5-day course of prednisolone in controlling asthma 5.
- A randomized controlled trial published in Trials found that a single dose of oral dexamethasone was clinically non-inferior to prednisolone in the treatment of exacerbations of asthma in children 6.
Pharmacological Properties
- Dexamethasone is a long-acting corticosteroid with a half-life of 36 to 72 hours, whereas prednisolone is relatively short-acting with a half-life of 12 to 36 hours 7, 6.
- The potency of dexamethasone is about 25 times greater than short-acting products like hydrocortisone 7.
Clinical Outcomes
- Studies have shown that dexamethasone can reduce the need for hospitalization, relapses, and subsequent hospital admission in patients with acute exacerbations of asthma 4, 5, 6.
- Dexamethasone has also been found to have fewer side effects compared to prednisolone, including less incidence of vomiting and gastrointestinal tract cramps 4, 8.