Dexamethasone

Category: hormone

Aliases: Decadron, 9α-fluoro-16α-methyl-prednisolone

Pharmacological Mechanism

9α-fluorinated, 16α-methylated synthetic GR agonist — long biologic half-life (~36–54 h), negligible mineralocorticoid activity. Pure anti-inflammatory / immunosuppressive profile without sodium retention. HPA-axis suppression at supraphysiologic doses is profound (a single 1 mg dose suppresses ACTH → cortisol for >24 h — the overnight dexamethasone suppression test).

Half-Life (t½)

PO: 4h, IV: 4h, IM: 4h

Dosing Guidelines

PO: Typical 3.67 mg (Range: 0.5–10 mg)
IV: Typical 3.67 mg (Range: 0.5–10 mg)
IM: Typical 3.67 mg (Range: 0.5–10 mg)

Target Organ Systems

endocrine
immune-hematologic

Pathways It Modulates

Arachidonic acid cascade (inhibitor) — PLA2 (upstream)
Asthma (inhibitor) — GR (acute exacerbation)
Calcineurin / NFAT T-cell activation (inhibitor) — GR transrepression of NFAT-target cytokines
CD4 T-helper differentiation (inhibitor) — GR transrepression of effector cytokines (broad)
cGAS-STING cytosolic DNA sensing → type I IFN (inhibitor) — broad anti-IFN transcription (GR transrepression)
Circadian clock (activator) — GR → peripheral clock resetting
Hypothalamic-pituitary-adrenal axis (inhibitor) — CRH/ACTH negative feedback
Mineralocorticoid receptor (activator) — MR (cross-occupancy)
Necroptosis (inhibitor) — NF-κB / TNF-α downstream
Neuroinflammation (inhibitor) — GR transrepression of NF-κB target cytokines
NF-κB signaling (inhibitor) — NF-κB transrepression via GR
Pyroptosis (inhibitor) — NF-κB → ↓priming signal for inflammasome
TLR (Toll-like receptor) innate signaling (inhibitor) — NF-κB transrepression (downstream of TLR)

Chemical Identifiers

PubChem CID: 5743
Formula: C22H29FO5
Molecular weight: 392.46 g/mol
InChIKey: UREBDLICKHMUKA-CXSFZGCWSA-N
SMILES: C[C@@H]1C[C@H]2[C@@H]3CCC4=CC(=O)C=C[C@@]4([C@]3([C@H](C[C@@]2([C@]1(C(=O)CO)O)C)O)F)C