DEXAIR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DEXAIR (DEXAIR).
DEXAIR (dexamethasone) is a corticosteroid that binds to the glucocorticoid receptor, leading to modulation of gene expression and suppression of inflammatory mediators (e.g., cytokines, prostaglandins). It also inhibits leukocyte infiltration and reduces capillary permeability.
| Metabolism | Primarily hepatic metabolism via CYP3A4 enzyme. Dexamethasone is also metabolized by other pathways including reduction and conjugation. The major metabolite is 6-hydroxydexamethasone. |
| Excretion | Renal (urinary): ~65-75% as unchanged drug and metabolites; biliary/fecal: ~20-30% as metabolites; less than 10% unchanged in bile. |
| Half-life | Terminal elimination half-life: 3.0-4.5 hours in adults with normal renal function; prolonged to 8-12 hours in severe renal impairment (CrCl <30 mL/min). |
| Protein binding | Approximately 78-90% bound to albumin and corticosteroid-binding globulin (CBG) in a concentration-dependent manner. |
| Volume of Distribution | Vd: 0.5-1.0 L/kg, indicating distribution into total body water and some tissue binding (100-200 L for a 70 kg adult). |
| Bioavailability | Oral: 60-80% (first-pass metabolism reduces absorption); Inhalation: 20-40% (lung deposition and systemic absorption); Intravenous: 100%. |
| Onset of Action | Oral: 30-60 minutes; Intravenous: within 5 minutes; Inhalation: 1-2 hours (bronchodilation). |
| Duration of Action | Oral: 12-24 hours; Intravenous: 6-12 hours; Inhalation: 12 hours (for asthma control). |
| Molecular Weight | 392.46 |
Inhalation: 2 inhalations (80 mcg each) twice daily, maximum 640 mcg/day.
| Dosage form | OINTMENT |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | No specific guidelines; caution in severe hepatic impairment due to potential for increased systemic exposure. |
| Pediatric use | Children 6-12 years: 1-2 inhalations (40-80 mcg) twice daily; maximum 320 mcg/day. Children >12 years: same as adult. |
| Geriatric use | No specific dose adjustment; monitor for adverse effects due to potential decreased hepatic function. |
| 1st trimester | Limited data; dexamethasone is a corticosteroid that crosses the placenta. Use only if clearly needed (e.g., maternal autoimmune disease). First-trimester use associated with small increase in risk of oral clefts. |
| 2nd trimester | Use only if benefit outweighs risk. Monitor for fetal growth restriction and adrenal suppression. |
| 3rd trimester | May be used for fetal lung maturation (betamethasone preferred). Chronic use may cause fetal adrenal suppression, growth restriction, and possibly premature birth. |
Clinical note
Comprehensive clinical and safety monograph for DEXAIR (DEXAIR).
| Placental transfer | Dexamethasone crosses the placenta efficiently; fetal concentrations are approximately 80% of maternal levels. Metabolized by placental 11β-HSD2 to a lesser extent than prednisolone. |
| Breastfeeding | Dexamethasone is excreted into breast milk in low concentrations. Short-term use is considered compatible with breastfeeding; however, high doses or prolonged use may suppress infant adrenal function and growth. Monitor infant for signs of adrenal suppression. |
■ FDA Black Box Warning
None. Dexamethasone does not carry an FDA black box warning. However, corticosteroids in general may cause serious adverse effects (e.g., immunosuppression, adrenal suppression).
| Serious Effects |
Systemic fungal infectionsHypersensitivity to dexamethasone or any component
| Precautions | Immunosuppression: Increased risk of infections, reactivation of latent infections (e.g., tuberculosis, hepatitis B, herpes zoster)., Adrenal suppression: Prolonged use can lead to hypothalamic-pituitary-adrenal axis suppression; abrupt withdrawal may cause adrenal crisis., Osteoporosis: Long-term use increases risk of bone loss and fractures., Gastrointestinal effects: Increased risk of peptic ulcer disease and GI hemorrhage, especially with NSAIDs., Corticosteroid-induced myopathy: May cause proximal muscle weakness., Psychiatric effects: May cause euphoria, insomnia, mood swings, or psychosis., Growth suppression: In children, long-term use may inhibit growth., Endocrine effects: May cause hyperglycemia, diabetes mellitus, or Cushing's syndrome., Ocular effects: Prolonged use increases risk of cataracts and glaucoma., Vaccination: Avoid live vaccines during therapy; killed vaccines may have reduced efficacy., Fluid and electrolyte disturbances: May cause sodium retention, potassium loss, and fluid overload., Use in pregnancy: Weigh benefits vs risks; may cause fetal harm (e.g., adrenal insufficiency in neonates)., Use in lactation: Excreted in breast milk; caution advised. |
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| Lactation Rating | L3 - Moderately Safe |
| Teratogenic Risk | DEXAIR (dexamethasone) is a corticosteroid. In first trimester, there is a possible increased risk of oral clefts (odds ratio ~3.4). Second/third trimester use may cause fetal adrenal suppression, intrauterine growth restriction, and premature birth. Chronic high doses may increase risk of preterm delivery and low birth weight. Overall, benefit-risk assessment is necessary. |
| Fetal Monitoring | Monitor maternal blood pressure, blood glucose, and signs of infection. Fetal monitoring includes ultrasound for growth restriction and amniotic fluid volume. If used near term, monitor neonatal adrenal function and respiratory status. |
| Fertility Effects | No direct evidence of impaired fertility in humans; however, reversible suppression of endogenous cortisol may affect ovulation and spermatogenesis at high doses. In men, high doses may reduce sperm count and motility temporarily. |
| Food/Dietary | Avoid grapefruit and grapefruit juice, which may increase dexamethasone levels. Limit high-sodium foods to reduce fluid retention. Maintain adequate calcium and vitamin D intake. |
| Clinical Pearls | Dexair (dexamethasone) is a potent corticosteroid with long duration; use with caution in patients with diabetes, hypertension, or osteoporosis. Monitor for adrenal suppression upon abrupt withdrawal. For acute asthma exacerbation, oral dexamethasone 16 mg daily for 1-2 days is as effective as a 5-7 day prednisone taper. Avoid live vaccines. Intrathecal use can cause arachnoiditis. Not suitable for primary CNS lymphoma without whole-brain radiation. |
| Patient Advice | Take exactly as prescribed; do not stop suddenly without doctor's guidance to avoid withdrawal symptoms. · Report any signs of infection (fever, sore throat), mood changes, or unusual weight gain. · May cause increased blood sugar; monitor if diabetic. · Avoid live vaccines (e.g., MMR, nasal flu) while on this medication. · Long-term use may increase risk of osteoporosis; ensure adequate calcium and vitamin D intake. |