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Dosage Adjustments

Increasing the dose

Increase the dose of Leventa in 10 μg/kg increments if after 4 weeks of treatment

• clinical signs have not improved and
• the post-dosing tT4 value is <20 nmol/l (<1.6 μg/dl)

For example, a dog receiving Leventa at 20 μg/kg once daily should now receive 30 μg/kg once daily. Peak tT4 and TSH concentrations should be reevaluated after 4 weeks and further dose adjustments made as necessary.

Leventa should be administered at the same time every day. The absorption of L-thyroxine is influenced by food. In order to achieve consistent absorption administer L-thyroxine 2-3 hours prior to feeding to maximize the degree of absorption and minimize variation in absorption. If L-thyroxine is administered less than 2 hours before feeding, at or after feeding, the feed given (type and amount) should be standardized.

Reducing the dose

Discontinue use of Leventa if signs of thyrotoxicosis are present.

• Signs usually resolve in 1-3 days.¹
• Treatment can be restarted at a lower dose when clinical signs have resolved.

If clinical signs have improved, there are no signs of thyrotoxicosis and tT4 >95 nmol/l (>7.4 µg/dl) reduce the dose of Leventa in 10 μg/kg increments.

Many hypothyroid dogs will initially lose weight when starting on a replacement therapy. It may be necessary to decrease the dose of Leventa based on the new body weight. By monitoring the serum T4 and TSH concentrations 4 weeks after starting a dog on Leventa or after any dose change, adjustments to the dose of Leventa may be made accordingly.

References

1. Nelson RW & Feldman EC. (2004) Hypothyroidism. In: Canine and Feline Endocrinology and Reproduction. 3rd Edition. Saunders, St Louis, MO, USA. pp 86-142.

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