Zycortal

Subcutaneous use.

Prior to use, gently shake the vial to resuspend the veterinary medicinal product.

Use an appropriately graduated syringe to accurately administer the required dose volume. This is particularly important when injecting small volumes.

Zycortal replaces the mineralocorticoid hormones only. Dogs with combined glucocorticoid and mineralocorticoid deficiency should also receive a glucocorticoid such as prednisolone taking into account the current scientific knowledge.

Zycortal is intended for long term administration at intervals and doses dependent upon individual response. Tailor the dose of Zycortal and the concurrently administered glucocorticoid replacement therapy to the individual dog based on clinical response and normalization of Na and K serum concentrations.

Initial dose of Zycortal:

The initial dose is 2.2 mg/kg body weight, administered by subcutaneous injection.

Interim monitoring visit:

Re-evaluate the dog and measure the serum sodium/potassium ratio (Na /K ratio) approximately 10 days after the first dose (which is the time to maximum concentration (T_max) of desoxycortone). If the dog’s clinical signs have worsened or not resolved, adjust the dose of glucocorticoid and/or investigate other causes of the clinical signs.

Second dose of Zycortal:

At approximately 25 days after the first dose, re-evaluate the dog and measure the Na /K ratio.

• If the dog is both clinically normal and has a normal Na⁺/K⁺ ratio (i.e. 27 to 32) on Day 25, adjust the dose based on the Day 10 Na /K ratio using the guidelines in Table 1, below.

• If the dog is clinically normal and has a Na /K ratio > 32 on Day 25, either adjust the dose based on the Day 10 Na /K ratio according to Table 1 or delay the dose (see Prolonging the dosing interval).

• If the dog is either not clinically normal or if the Na /K ratio is abnormal on Day 25, adjust the dose of glucocorticoid or Zycortal (see Subsequent doses and long term management).

Prolonging the dosing interval:

If the dog is clinically normal and the Day 25 Na /K ratio is > 32, it is possible to prolong the dosing interval instead of adjusting the dose as described in Table 1. Evaluate the electrolytes every 5–9 days until the Na /K ratio is < 32, and then administer 2.2 mg/kg of Zycortal.

Subsequent doses and long term management:

Once the optimal dose and dosing interval have been determined, maintain the same regimen. If the dog develops abnormal clinical signs or Na or K serum concentrations, use the following guidelines for subsequent doses:

• Clinical signs of polyuria/polydipsia: Decrease the glucocorticoid dose first. If the polyuria/polydipsia persists and the Na /K ratio is >32, then decrease the dose of Zycortal without changing the dosing interval.

• Clinical signs of depression, lethargy, vomiting, diarrhoea or weakness: Increase the glucocorticoid dose.

• Hyperkalaemia, hyponatremia or Na /K ratio < 27: Decrease the Zycortal dosing interval by 2– 3 days or increase the dose.

• Hypokalaemia, hypernatremia or Na /K ratio > 32: Decrease the Zycortal dose.

Prior to a stressful situation, consider temporarily increasing the dose of glucocorticoid.

In the clinical trial, the mean final dose of desoxycortone pivalate was 1.9 mg/kg (range 1.2– 2.5 mg/kg) and the mean final dosing interval was 38.7 ± 12.7 days (range 20–99 days) with the majority of dogs having a dosing interval between 20 and 46 days.