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Brand

Azium

Availability

0.25 mg, 0.75 mg, 1 mg, 1.5 mg, 2 mg, 4 mg, 6 mg tablets
2mg/mL injectable
(human approved)available in: 0.5 mg/5ml and 0.5 mg/0.5ml elixir

Dexamethasone Sodium Phosphate

A highly soluable form, with more rapid onset and shorter duration. (*note: 1.3 mg of dexamethasone sodium phosphate is equal to 1 mg of dexamethasone).

Brand

Azium SP , Dexasone, Decadron

Availability

4mg/mL injectable (equivalent to 3mg/mL dexamethasone)

Pharmacology

Dexamethasone is a long acting florinated glucocorticoid with 25-30 times more potency than an equal weight of hydrocortisone. It is faster acting with longer duration than the intermediate oral agents prednisone and prednisolone.

Dexamethasone stimulates synthesis of enzymes required to decrease the inflammatory response. Its primary efficacy is that of a strong antiinflammatory, as well as an antiallergic agent.
Besides being an antiinflammatory, the drug will also suppress the immune response, stimulate bone marrow, and influence fat, protein, and carbohydrate metabolism. Although it is able to cause diuresis, there are more effective drugs for reducing edema.

The drug is readily absorbed into tissue, and rapidly distributed to kidneys, liver, muscle, and intestines. It is metabolized in the liver and primarily excreted by the kidneys.

The drug can be given orally , used topically, or by injection.

Indications

Used as a quick agent to reduce inflammation in ear infections causing wry neck/head tilt.
Can be used as support therapy in URI (upper respiratory infection) unresponsive to antimicrobials alone, or in serious to advanced lung infections (e.g.,pnuemonia) to reduce allergic response (especially where pathogen suspected to be mycoplasma).
Also used for swelling caused by injury, cerebral edema, neoplasia, and septic shock.

Drug Interactions or Contraindications

Do not give in active untreated infections or viral, and fungal diseases of the eye.

Use with caution in CHF and colitis.

Incompatible mixed in with doxorubicin HCL, daunorubicin HCL, and vancomycin. (*note updated correction: may be used concurrently with doxycycline)

Has only minor mineralcorticoid effect and should not be used alone to treat adrenal insufficiency.

When used with NSAIDS will increase GI distress or cause bleeding, use together cautiously.

Adverse Reactions

EENT:  cataracts, glaucoma

CV:  CHF, edema

GI:  Known to increase appetite but may have opposite effect in rats.

Skin:  delayed wound healing

Local:  atrophy at injection site

Other:  may mask or excacerbate infections already present.

Dosage Recommendations

Dexamethasone

0.5 mg/lb to 1 mg/lb , SQ or IM (if using this dose range in lbs. and changing to kg. It will be 1.0 mg/kg to 2.0 mg/kg) ⁴

or

0.5 mg/kg to 2.0 mg/kg , PO or SQ, then decreasing dose q12h x 3-14 days. ¹

or

FOR SHOCK ONLY give 4 mg/kg to 5 mg/kg , SQ, IM, IP, IV  ¹

or

Dexamethasone Sodium Phosphate

0.23 mg/lb to 0.9 mg/lb , PO or SQ, BID , then decreasing dose x 3-14 days  ³

or

The following are dosage guidelines recommended by “Dr. Mike” Hutchinson, DVM; Animal General, Cranberry Township, PA. This incorporates the use of dexamethasone in a treatment regimen for rats with early to mild URI, or with serious to advanced lung infections. This schedule is based on Dr. Hutchinson’s experience treating rats, and also from what he gleaned from current literature:

Early to mild URI (especially where pathogen suspected to be mycoplasma)
Dexamethasone at 0.5 mg/lb can be added to the treatment regimen, weaning down as follows:
0.5 mg/lb BID injectable or PO (oral) for 3 days
0.5 mg/lb SID for 3 days
0.25 mg/lb SID for 3 days
0.25 mg/lb orally every other day, three doses

Serious and Advanced Respiratory Illness:
dexamethasone 1 mg/lb BID, added to treatment regimen, then weaned down as follows:
1 mg/lb BID injectable or PO (oral) for 3 days
1 mg/lb SID for 3 days
0.5 mg/lb SID for 3 days
0.5 mg/lb orally every other day, three doses

Other veterinary recommended reduction schedules for dexamethasone may also be used.

For a complete treatment regimen incorporating dexamethasone along with antimicrobials: enrofloxacin and doxycycline , as well as nebulized treatments of gentocin and Albuterol see articles: Mycoplasma or Pneumoniain the Health section of the Rat Guide. Also see individual monographs for more information on specific antimicrobials and respiratory agents in the Medication section of the Rat Guide.

Dexamethasone has been shown, in the controlled studies cited below, to reduce plasma leakage, resolve Mycoplasma induced inflammation, and also reduce the number of Mycoplasma organisms even when used as the only therapy.

Am. J. Respir. Crit. Care Med., Vol 150, No. 5, Nov 1994, 1391-1401; Dexamethasone and oxytetracycline reverse the potentiation of neurogenic inflammation in airways of rats with Mycoplasma pulmonis infection; J.J. Bowden, TR Schoeb, J. R. Lindsey and D.M. McDonald; Cardiovascular Research Institute and Department of Anatomy, UCSF.

Am. J. Respir. Crit. Care Med., Vol 164, No. 10 Nov 2001, S39-S45; Angiogenesis and Remodeling of Airway Vasculature in Chronic Inflammation; Donald M. McDonald; Cardiovascular Research Institute and Department of Anatomy, UCSF.

Considerations

Recommended for single injection or for short duration.

Sudden withdrawal of drug may be fatal if given over an extended period of time, check with Veterinarian prior to stopping or to gradually reduce dosage.

Dexamethasone is preferred over Prednisone for use in rats.

Store at room temperature and protect from light.

Posted on June 23, 2003, 16:15, Last updated on March 17, 2008, 17:37 | Endocrine Hormones