Dosing and Administration:
These preparations are recommended for intramuscular and intrasynovial injection in horses and dogs, and intramuscular injection in cats.
INTRAMUSCULAR ADMINISTRATION AND DOSAGE 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.
Dogs and Cats: The average intramuscular dose for dogs is 20 mg. In accordance with the size of the dog and severity of the condition under treatment the dose may range from 2 mg in miniature breeds to 40 mg in medium breeds and even as high as 120 mg in extremely large breeds or dogs with severe involvement. The average intramuscular dose for cats is 10 mg with a range up to 20 mg.
Injections may be made at weekly intervals or in accordance with the severity of the condition and clinical response.
Horses: The usual intramuscular dose for horses is 200 mg repeated as necessary.
For maintenance therapy in chronic conditions initial doses should be reduced gradually until the smallest effective (ie individualized) dose is established. MEDROL® tablets containing methylprednisolone may also be used for maintenance in dogs and cats administered according to the recommended dose.
When treatment is to be withdrawn after prolonged and intensive therapy the dose should be reduced gradually.
If signs of stress are associated with the condition being treated the dose should be increased. If a rapid hormonal effect of maximum intensity is required as in anaphylactic shock the intravenous administration of highly soluble SOLU-DELTA-CORTEF® Sterile Powder containing prednisolone sodium succinate is indicated.
Intrasynovial Administration And Dosage 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 Sterile Aqueous Suspension 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.
Procedure for Intrasynovial Injection: The anatomy of the area to be injected should be reviewed in order to assure that the suspension is properly placed and to determine that large blood vessels or nerves are avoided. The injection site is located where the synovial cavity is most superficial. The area is prepared for aseptic injection of the medicament by the removal of hair and cleansing of the skin with alcohol or Mercresin® tincture. A sterile 18- to 21-gauge needle for horses 20- to 22-gauge needle for dogs on a dry syringe is quickly inserted into the synovial space and a small amount of synovial fluid withdrawn. If there is an excess of synovia and more than 1 mL of suspension is to be injected it is well to aspirate a volume of fluid comparable to that which is to be injected. With the needle in place the aspirating syringe is removed and replaced by a second syringe containing the proper amount of suspension which is then injected. In some animals a transient pain is elicited immediately upon injection into the affected cavity. This pain varies from mild to severe and may last for a few minutes up to 12 hours. After injection the structure may be moved gently a few times to aid mixing of the synovial fluid and the suspension. The site may be covered with a small sterile dressing.
Areas not suitable for injection are those that are anatomically inaccessible such as spinal joints and those like the sacroiliac joints which are devoid of synovial space. Treatment failures are most frequently the result of failure to enter the synovial space. If failures occur when injections into the synovial spaces are certain as determined by aspiration of fluid repeated injections are usually futile. Local therapy does not alter the underlying disease process and whenever possible comprehensive therapy including physiotherapy and orthopedic correction should be employed.
The single intrasynovial dose depends on the size of the part which corresponds to the size of the animal. The interval between repeated injections depends on the duration of relief obtained.
Horses: The average initial dose for a large synovial space in horses is 120 mg with a range from 40 to 240 mg. Smaller spaces will require a correspondingly lesser dose.
Dogs: The average initial dose for a large synovial space in dogs is 20 mg. Smaller spaces will require a correspondingly lesser dose.
