A patient on long-term prednisolone develops adrenal suppression. Which feature best explains why morning dosing is preferred over evening dosing for chronic corticosteroid therapy?
- A Morning cortisol levels are lower, allowing exogenous corticosteroid to fill a trough without further suppressing the pituitary
- B Endogenous cortisol peaks around 8 AM; administering exogenous steroid at the same time causes minimum additional suppression of the pituitary-adrenal axis by avoiding the trough when CRH/ACTH secretion would normally be rising ✓
- C Gastric acid secretion is highest in the morning, enhancing prednisolone absorption and reducing required dose
- D Morning dosing avoids nocturnal inhibition of growth hormone release, reducing growth suppression in children
Correct answer: B. Endogenous cortisol peaks around 8 AM; administering exogenous steroid at the same time causes minimum additional suppression of the pituitary-adrenal axis by avoiding the trough when CRH/ACTH secretion would normally be rising
Explanation
Cortisol secretion follows a circadian rhythm, peaking around 6–8 AM and reaching a nadir at midnight. ACTH and CRH are released in greatest pulses in the early morning hours just before the cortisol peak. Administering exogenous corticosteroids in the morning coincides with the natural secretory surge, thereby adding to an already-elevated cortisol milieu rather than suppressing the hypothalamic-pituitary axis during the sensitive nocturnal trough when CRH neurons are most active.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.