Systemic corticosteroids are an essential class of medication that is used to treat acute inflammation. One of the major indications that this class is used to treat is an acute asthma exacerbation. This is especially true in pediatric patients. In this article, I will outline some of the most important pharmacokinetic differences to remember when comparing prednisolone versus dexamethasone.
Potency – Prednisolone Versus Dexamethasone
When first contrasting prednisolone versus dexamethasone, we should look at the potency. Prednisolone isn’t nearly as potent as dexamethasone. As a reminder, potency refers to the amount of drug it takes to produce a physiological response. Dexamethasone takes a lower amount of drug on a mg per mg basis than prednisolone to create the same physiological response. The approximate equivalent dosing is dexamethasone 0.75 mg to 5 mg of prednisolone. Our friends at Pyrls.com have an excellent chart of equivalent systemic corticosteroid equivalencies (including methylprednisolone, hydrocortisone, triamcinolone, and others). You can sign up for a free account here and get access to that chart as I have done!
Comparison of Dosage Forms
Dexamethasone has both oral and IV options. The dual administration possibilities help give clinicians a little more comfort in tolerability if one or the other has been used before. In addition to the proven tolerability record, if a patient has had IV or PO previously, the injectable option gives a unique opportunity to bypass the GI tract in patients who have the potential for nausea and vomiting. Prednisolone is only available as an oral solution, so the only way we can give this medication is by mouth.
Duration of Action – Prednisolone Versus Dexamethasone
For the prednisolone versus dexamethasone comparison, it is important to recognize differences in the duration of action. Dexamethasone has a longer biological half-life than prednisolone and therefore can be given for a shorter period of time. Dexamethasone’s action can extend for up to 2-3 days while prednisolone tends to be more in the range of 12-24 hours. In the classification of systemic corticosteroids, dexamethasone is classified as a long-acting agent while prednisolone is considered an intermediate-acting agent.
The primary reason the duration of action matters is for dosing. Prednisolone in an acute asthma exacerbation is most often dosed twice daily. Dexamethasone, because of its longer duration of action may only need to be dosed on a once-daily basis. This can be a significant advantage of dexamethasone, particularly in patients that you know have a history of poor adherence.
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