Metabolic and Hormonal Effects

Methylprednisolone, an anti-inflammatory steroid synthesized and developed in the
Research Laboratories of The Upjohn Company, is the 6-methyl derivative of
prednisolone. Exceeding prednisolone in anti-inflammatory potency and having even
less tendency than prednisolone to induce sodium and water retention,methylprednisolone
offers the advantage over older corticosteroids of affording
equally satisfactory anti-inflammatory effect with the use of lower doses and with an
enhanced split between anti-inflammatory and mineralocorticoid activities. Estimates
of the relative potencies of methylprednisolone and prednisolone range from
1.13 to 2.1, with an average of 1.5. In anti-inflammatory activity, as measured by the
granuloma pouch assay, methylprednisolone is twice as active as prednisolone. In
mineralocorticoid activity (ie, the capacity to induce retention of sodium and water in
the adrenalectomized rat) methylprednisolone is slightly less active than prednisolone.
The duration of plasma steroid levels following rapid intravenous injection in intact
dogs is appreciably longer for methylprednisolone than for prednisolone, the
respective “half-life” value for the two steroids being 80.9 ± 7.5 minutes for methylprednisolone
and 71.3 ±1.7 minutes for prednisolone.

While the effect of parenterally administered DEPO-MEDROL is prolonged, it has
the same metabolic and anti-inflammatory actions as orally administered methylprednisolone
acetate.

Musculoskeletal Conditions

 As with other adrenal steroids, DEPO-MEDROL has
been found useful in alleviating the pain and lameness associated with acute localized
arthritic conditions and generalized arthritic conditions. It has been used successfully
to treat rheumatoid arthritis, traumatic arthritis, osteoarthritis, periostitis, tendinitis,
synovitis, tenosynovitis, bursitis, and myositis of horses; traumatic arthritis,
osteoarthritis, and generalized arthritic conditions of dogs. Remission of musculoskeletal
conditions may be permanent, or symptoms may recur, depending on the cause and
extent of structural degeneration.

Allergic Conditions

This preparation is especially beneficial in relieving pruritus
and inflammation of allergic dermatitis, acute moist dermatitis, dry eczema, urticaria,
bronchial asthma, pollen sensitivities and otitis externa in dogs; allergic dermatitis and
moist and dry eczema in cats. Onset of relief may begin within a few hours to a few
days following injection and may persist for a few days to six weeks. Symptoms may
be expected to recur if the cause of the allergic reaction is still present, in which case
retreatment may be indicated. In treating acute hypersensitivity reactions, such as
anaphylactic shock, intravenous SOLU-DELTA-CORTEF® Sterile Powder containing
prednisolone sodium succinate, as well as other appropriate treatments, should be
used.

Overwhelming Infections with Severe Toxicity

In dogs and cats moribund from
overwhelmingly severe infections for which antibacterial therapy is available (eg,
critical pneumonia, pyometritis), DEPO-MEDROL may be lifesaving, acting to inhibit
the inflammatory reaction, which itself may be lethal; preventing vascular collapse
and preserving the integrity of the blood vessels; modifying the patient’s reaction to
drugs; and preventing or reducing the exudative reaction which often complicates
certain infections. As supportive therapy, it improves the general attitude of the animal
being treated. All necessary procedures for the establishment of a bacterial diagnosis
should be carried out whenever possible before institution of therapy. Corticosteroid
therapy in the presence of infection should be administered for the shortest possible
time compatible with maintenance of an adequate response, and antibacterial therapy
should be continued for at least three days after the hormone has been withdrawn.
Combined hormone and antibacterial therapy does not obviate the need for indicated
surgical treatment.

Other Conditions

In certain conditions where it is desired to reduce inflammation,
vascularization, fibroblastic infiltration, and scar tissue, the use of DEPO-MEDROL
should be considered. Snakebite of dogs also is an indication for the use of this
suspension because of its anti-toxemic, anti-shock, and anti-inflammatory activity. It
is particularly effective in reducing swelling and preventing sloughing. Its employment
in the treatment of such conditions is recommended as a supportive measure to
standard procedures and time-honored treatments and will give comfort to the animal
and hasten complete recovery.

INTRAMUSCULAR

Following intramuscular injection of methylprednisolone acetate, a prolonged systemic effect results. The dose varies with the size of the animal patient, the severity of the condition under treatment, and the animal’s response to therapy.

INTRASYNOVIAL

Methylprednisolone acetate, a slightly soluble ester of methylprednisolone, is capable of producing a more prolonged local anti-inflammatory effect than equimolar doses of hydrocortisone acetate. Following intrasynovial injection, relief from pain may be experienced within 12 to 24 hours. The duration of relief varies, but averages three to four weeks, with a range of one to five or more weeks. Injections of methylprednisolone acetate have been well tolerated. Intrasynovial (intra-articular) injections may occasionally result in an increased localized inflammatory response.

Intrasynovial injection is recommended as an adjuvant to general therapeutic measures to effect suppression of inflammation in one or a few peripheral structures when (1) the disease is limited to one or a few peripheral structures; (2) the disease is widespread with one or a few peripheral structures actively inflamed; (3) systemic therapy with other corticoids or corticotropin controls all but a few of the more actively involved structures; (4) systemic therapy with cortisone, hydrocortisone, or corticotropin is contraindicated; (5) joints show early but actively progressing deformity (to enhance the effect of physiotherapy and corrective procedures); and (6) surgical or other orthopedic corrective measures are to be or have been done.

The action of DEPO-MEDROL injected intrasynovially appears to be well localized since significant metabolic effects characteristic of systemic administration of adrenal steroids have not been observed. In a few instances mild and transient improvement of structures other than those injected have been reported. No other systemic effects have been noted. However, it is possible that mild systemic effects may occur following intrasynovial administration, and this possibility is greater the larger the number of structures injected and the higher the total dose employed.