Dexamethasone information from DrugsUpdate  

Pharmacodynamics

Pharmacokinetics

Dexamethasone is a synthetic glucocorticoid which decreases inflammation by inhibiting the migration of leukocytes and reversal of increased capillary permeability. It suppresses normal immune response.
Onset: As acetate: Prompt.
Duration: 72 hr.
Absorption: Readily absorbed from the GI tract (Oral).
Distribution: Readily crosses the placenta. Protein binding: About 77%.
Metabolism: Hepatic.
Excretion: Via urine (65% of the dose within 24 hr). Half-life: About 190 min.

Dexamethasone Indications / Dexamethasone Uses

Information Not Available

Dexamethasone Adverse Reactions / Dexamethasone Side Effects

Growth retardation, osteoporosis, peptic ulcer, glaucoma and subcapsular cataracts, vertebral compression fractures. Cushing-like features, pancreatic dysfunction and pancreatitis, GI upsets, increased appetite, increased fragility of the skin. Increased susceptibility to infection. Topical application: Dermal atrophy, local irritation, folliculitis, delayed wound healing, systemic absorption and toxicity with occlusive dressing on application to large areas of the body and broken skin. Topical application to eye: Corneal ulcers, glaucoma and reduced visual ability. Inhalation: Hoarseness, candidiasis of mouth and throat. Intra-articular inj: Aseptic necrosis of bone and joint damage.
Potentially Fatal: HPA supression; CV collapse on rapid IV admin.

Precautions

General:
The lowest possible dose of corticosteroids should be used to control the condition under treatment. When reduction in dosage is possible, the reduction should be gradual.
Since complications of treatment with corticosteroids are dependent on the size of the dose and the duration of treatment, a risk/benefit decision must be made in each individual case as to dose and duration of treatment and as to whether daily or intermittent therapy should be used.
Kaposi's sarcoma has been reported to occur in patients receiving corticosteroid therapy, most often for chronic conditions. Discontinuation of corticosteroids may result in clinical improvement.

Cardio-Renal
As sodium retention with resultant edema and potassium loss may occur in patients receiving corticosteroids, these agents should be used with caution in patients with congestive heart failure, hypertension, or renal insufficiency.

Endocrine
Drug-induced secondary adrenocortical insufficiency may be minimized by gradual reduction of dosage. This type of relative insufficiency may persist for months after discontinuation of therapy; therefore, in any situation of stress occurring during that period, hormone therapy should be reinstituted. Since mineralocorticoid secretion may be impaired, salt and/or a mineralocorticoid should be administered concurrently.

Gastrointestinal
Steroids should be used with caution in active or latent peptic ulcers, diverticulitis, fresh intestinal anastomoses, and nonspecific ulcerative colitis, since they may increase the risk of a perforation.
Signs of peritoneal irritation following gastrointestinal perforation in patients receiving corticosteroids may be minimal or absent.
There is an enhanced effect due to decreased metabolism of corticosteroids in patients with cirrhosis.

Musculoskeletal
Corticosteroids decrease bone formation and increase bone resorption both through their effect on calcium regulation (i.e., decreasing absorption and increasing excretion) and inhibition of osteoblast function. This, together with a decrease in the protein matrix of the bone secondary to an increase in protein catabolism, and reduced sex hormone production, may lead to inhibition of bone growth in pediatric patients and the development of osteoporosis at any age. Special consideration should be given to patients at increased risk of osteoporosis (e.g., postmenopausal women) before initiating corticosteroid therapy.

Neuro-Psychiatric
Although controlled clinical trials have shown corticosteroids to be effective in speeding the resolution of acute exacerbations of multiple sclerosis, they do not show that they affect the ultimate outcome or natural history of the disease. The studies do show that relatively high doses of corticosteroids are necessary to demonstrate a significant effect.
An acute myopathy has been observed with the use of high doses of corticosteroids, most often occurring in patients with disorders of neuromuscular transmission (e.g., myasthenia gravis), or in patients receiving concomitant therapy with neuromuscular blocking drugs (e.g., pancuronium). This acute myopathy is generalized, may involve ocular and respiratory muscles, and may result in quadriparesis. Elevation of creatinine kinase may occur. Clinical improvement or recovery after stopping corticosteroids may require weeks to years.
Psychic derangements may appear when corticosteroids are used, ranging from euphoria, insomnia, mood swings, personality changes, and severe depression, to frank psychotic manifestations. Also, existing emotional instability or psychotic tendencies may be aggravated by corticosteroids.

Ophthalmic
lntraocular pressure may become elevated in some individuals. If steroid therapy is continued for more than 6 weeks, intraocular pressure should be monitored.

Special Precautions

Patients with hypothyroidism; cirrhosis, hypertension, CHF, ulcerative colitis, thromboembolic disorders, osteoporosis, glaucoma, cataracts or TB of the eye, diabetes, peptic ulcer. Monitor blood glucose levels in diabetics and coagulation indices in patients on warfarin. Elderly, children and adolescent; pregnancy and lactation.

Other Drug Interactions

Increased risk of hypokalaemia when used concurrently with potassium-depleting drugs such as amphotericin B and loop diuretics. Reduces efficacy of isoniazid, salicylates, vaccines and toxoids. Increased activity of dexamethasone and cyclosporin when used together. Concurrent use with aspirin or ethanol may lead to increased GI side effects.
Potentially Fatal: Reduced efficacy in combination with ephedrine, cholestyramine, phenytoin, phenobarbital and rifampicin.

Other Interactions

Food Interactions: Dexamethasone interferes with calcium absorption. Limit caffeine

Dosage

Oral
Anti-inflammatory
Adult: 0.75-9 mg daily in 2-4 divided doses; may also be given via IM/IV admin.
Child: 1 mth–18 yr: 10–100 mcg/kg daily in 1–2 divided doses via oral admin, adjusted according to response; up to 300 micrograms/kg daily may be used in emergency situations.
Oral
As a screening test for Cushing's syndrome
Adult: 0.5 mg every 6 hr for 48 hr after determining baseline 24-hr urinary 17-hydroxycorticosteroid (17-OHCS) concentrations. During the second 24 hr of dexamethasone admin, urine is collected and analysed for 17-OHCS. Alternatively, after a baseline plasma cortisol determination, 1 mg may be given at 11 pm and plasma cortisol determined at 8 am the next morning. Plasma cortisol and urinary output of 17-OHCS are depressed after dexamethasone admin in normal individuals but remain at basal levels in patients with Cushing’s syndrome.
Oral
Acute exacerbations in multiple sclerosis
Adult: 30 mg daily for 1 wk followed by 4-12 mg daily for 1 mth.
Child: 1 mth–12 yr: 100–400 mcg/kg daily in 1–2 divided doses; 12–18 yr: Initially 0.5–24 mg daily. Max. 24 mg daily.
Intravenous
Unresponsive shock
Adult: As phosphate: Initially, 40 mg or 1-6 mg/kg as a single IV inj, may repeat every 2-6 hr. Continue high-dose treatment only until patient’s condition has stabilised and not to be continued beyond 48–72 hr.
Intravenous
Bacterial meningitis
Adult: 0.15 mg/kg 4 times daily, to be given 10-20 min before or with the 1st dose of anti-infective treatment. Treatment should be given for the first 2-4 days of the anti-infective treatment.
Child: As phosphate: 2 mth–18 yr: 150 mcg/kg every 6 hr for 4 days, starting before or with 1st dose of antibacterial treatment.
Intravenous
Prophylaxis of chemotherapy-related emesis
Adult: Prevention: 10-20 mg 15-30 minutes before admin of chemotherapy on each treatment day. For continuous infusion regimen: 10 mg every 12 hr on each treatment day. For midly emetogenic regimen: 4 mg every 4-6 hr.
Parenteral
Cerebral oedema caused by malignancy
Adult: As phosphate: 10 mg IV followed by 4 mg IM every 6 hr until response is achieved, usually after 12-24 hr. May reduce dosage after 2-4 days then gradually discontinued over 5-7 days. In severe cases, an initial dose of 50 mg IV may be given on day 1, with 8 mg every 2 hr, reduced gradually over 7-13 days. Maintenance dose: 2 mg 2-3 times daily.
Child: As phosphate: <35 kg: Initially 20 mg, then 4 mg every 3 hr for 3 days, then 4 mg every 6 hr for 1 day, then 2 mg every 6 hr for 4 days, then decrease by 1 mg daily. >35 kg: Initially 25 mg, then 4 mg every 2 hr for 3 days, then 4 mg every 4 hr for 1 day, then 4 mg every 6 hr for 4 days, then decrease by 2 mg daily. Doses are given via IV inj.
Ophthalmic
Ophthalmic inflammation
Adult: As 0.1% suspension: Apply 1-2 drops into the affected eye/s 4-6 times daily in mild disease, up to hrly admin in more severe disease. As 0.05% ointment: Apply 0.5-1 inch ribbon of ointment into the conjunctival sac(s) up to 4 times daily. Reduce to once daily dosing once conditon has improved.
Intra-articular
Inflammatory joint diseases
Adult: 0.8-4 mg depending on the size of the affected joint. For soft-tissue inj, 2-6 mg may be used. May repeat inj every 3-5 days to every 2-3 wk.

Food(before/after)

Should be taken with food

Dexamethasone and Pregnancy

Caution when used during pregnancy.
Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.
D in 1st trimester
Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Dexamethasone and Lactation

Caution when used during lactation

Dexamethasone and Children

Information Not Available

Dexamethasone and Other Contraindications

Hypersensitivity; active untreated infections; ophthalmic use in viral, fungal disease of the eye.

Storage

Intra-articular: Store at 15-30°C.
Intravenous: Store at 15-30°C.
Ophthalmic: Store at 15-30°C.
Oral: Store at 15-30°C.
Parenteral: Store at 15-30°C.

Lab interference

Intra-articular: Store at 15-30°C.
Intravenous: Store at 15-30°C.
Ophthalmic: Store at 15-30°C.
Oral: Store at 15-30°C.
Parenteral: Store at 15-30°C.