Dexamethasone acetate

BRAND NAMES

• Decadron‑LA - a long‑acting injectable form that is largely discontinued in the U.S.

• Dalanone DP -  another injectable formulation, which in many cases has been replaced or discontinued.

• Maxidex - an ophthalmic (eye‑drop) preparation, typically using the phosphate salt or generic equivalents.

• Sofradex - a combination ear/eye drop or ointment containing framycetin sulphate together with dexamethasone acetate.

• Pi Yan Ping - a topical cream brand marketed in China.

• Horster - a brand name from an ingredient supplier in India.

MECHANISM OF  ACTION

Dexamethasone acetate works primarily by binding to intracellular glucocorticoid receptors, which then translocate into the nucleus and regulate gene expression. This regulation suppresses the synthesis of pro‑inflammatory mediators (such as prostaglandins and cytokines), reduces immune cell activity, and stabilises cell membranes. In addition to these genomic effects, it also exhibits non‑genomic actions that contribute to its anti‑inflammatory and immunosuppressive activity.

PHARMACOKINETICS:

Absorption

Dexamethasone acetate absorption varies with the administration route. Intramuscular injections are efficiently absorbed and converted to active dexamethasone, while oral absorption depends on the formulation. Topical application is slower and less efficient unless absorption enhancers are used.

Distribution

Dexamethasone acetate is widely distributed in the body and binds to plasma proteins (around 77%). Its tissue concentrations depend on the administration route: systemic delivery distributes the drug throughout tissues, while localized routes, such as ocular administration, achieve high concentrations at target sites (e.g., iris and aqueous humor) with minimal systemic exposure.

Metabolism

Dexamethasone acetate is converted to dexamethasone, which is subsequently metabolized in the liver, mainly by the cytochrome P450 enzyme CYP3A4, forming 6‑hydroxy‑dexamethasone and other metabolites.

Excreation

Dexamethasone acetate is mainly eliminated through urine and feces following hepatic metabolism. Over 95% of the drug is cleared within three days, primarily as metabolites. Some of these metabolites can also be detected in tissues such as hair, allowing for medium- to long-term monitoring.

PHARMACODYNAMICS

Dexamethasone acetate exerts its pharmacodynamic effects as a potent glucocorticoid,providing strong anti-inflammatory and immunosuppressive actions. It dampens the immune response by reducing lymphocyte numbers and activity, decreasing capillary permeability, and stabilizing lysosomal membranes, thereby inhibiting the production of inflammatory mediators such as prostaglandins and cytokines.

ADMINISTRATION

Dexamethasone acetate is a corticosteroid mainly given through intramuscular (IM), intra-articular, or intralesional injections. As a less water-soluble, long-acting “depot” formulation, it provides sustained effects, unlike the water-soluble dexamethasone sodium phosphate, which is intended for rapid intravenous (IV) administration.

DRUG INTERACTIONS

Dexamethasone acetate interacts with many medications, mainly because it influences liver drug metabolism and can alter electrolyte balance. Important interactions occur with diabetes medications, anticoagulants, NSAIDs, and specific antibiotics or antifungal agents.

FOOD INTERACTIONS

Dexamethasone acetate interacts with many medications, mainly because it influences liver drug metabolism and can alter electrolyte balance. Important interactions occur with diabetes medications, anticoagulants, NSAIDs, and specific antibiotics or antifungal agents.

CONTRAINDICATIONS

Dexamethasone acetate is a powerful corticosteroid that is contraindicated in individuals with known hypersensitivity to the drug or any of its ingredients. It is also unsuitable for patients with certain conditions due to its immunosuppressive properties and potential for adverse effects.

Major contraindications include:

• Systemic Fungal Infections: Use of dexamethasone may worsen systemic fungal infections and should be avoided unless required to manage life-threatening reactions.

• Active Viral Infections: This includes active ocular herpes simplex, varicella (chickenpox), herpes zoster (shingles), and viral hepatitis, as dexamethasone can aggravate these infections.

• Use of Live or Live-Attenuated Vaccines: Because dexamethasone suppresses immune function, it can interfere with antibody production and increase the risk of vaccine-derived infection. Routine immunizations should, if possible, be postponed until treatment has ended.

OVER DOSE

An overdose of dexamethasone acetate can lead to an intensification of its pharmacologic effects rather than distinct toxic symptoms. Acute over dosage is rare but may cause symptoms such as fluid retention, elevated blood pressure, increased blood sugar levels, and electrolyte imbalances (particularly hypokalemia). Prolonged excessive use can result in Cushing’s syndrome, suppression of the hypothalamic-pituitary-adrenal (HPA) axis, muscle weakness, osteoporosis, and increased susceptibility to infections. Treatment of overdose is primarily supportive and symptomatic. In cases of chronic overdose, gradual dose reduction rather than abrupt withdrawal is recommended to allow recovery of normal adrenal function.

SIDE EFFECTS

• Weight gain and increased appetite

• Mood alterations such as anxiety, irritability, depression, or euphoria

• Trouble sleeping (insomnia)

• Stomach discomfort or indigestion (taking the medication with food or milk may help)

• Headache and dizziness

• Fluid retention leading to swelling of the hands, ankles, or feet

• Skin changes, including acne, thinning or dryness, easy bruising, or red/purple patches

• Excessive sweating

• Muscle weakness or joint pain

• Irregular or missed menstrual periods

TOXICITY

Dexamethasone acetate, a potent and long-acting corticosteroid, exhibits a toxicity profile primarily associated with the known side effects of glucocorticoids, with risks increasing with higher doses and longer treatment durations. The toxic effects can be widespread, affecting various organ systems, including endocrine, immune, musculoskeletal, and cardiovascular systems.