Product Name:  Soloxine [Levothyroxine] 0.6 mg, 250 Tablets

Description: 

Indications:
Provides thyroid replacement therapy in all conditions of inadequate production of thyroid hormones. Hypothyroidism is the generalized metabolic disease resulting from deficiency of the thyroid hormones levothyroxine (T4) and liothyronine (T3). SOLOXINE® (levothyroxine sodium) will provide levothyroxine (T4) as a substrate for the physiologic deiodination to liothyronine (T3). Administration of levothyroxine sodium alone will result in complete physiologic thyroid replacement.

Pharmacology:
Levothyroxine sodium acts, as does endogenous thyroxine, to stimulate metabolism, growth, development and differentiation of tissues. It increases the rate of energy exchange and increases the maturation rate of the epiphyses. Levothyroxine sodium is absorbed rapidly from the gastro-intestinal tract after oral administration. Following absorption, the compound becomes bound to the serum globulin fraction. For purposes of comparison, 0.1 mg of levothyroxine sodium elicits a clinical response approximately equal to that produced by one grain (65 mg) of desiccated thyroid.

Dosage and Administration:
The initial recommended daily dose is 0.1 mg/10 lbs. (4.5 kg) of body weight. The dosage may then be adjusted according to the patient's response by monitoring T4 blood levels at time intervals of four (4) weeks.
SOLOXINE® tablets may be administered orally or placed in the food.

Contraindications:
Levothyroxine sodium therapy is contraindicated in thyrotoxicosis, acute myocardial infarction and uncorrected adrenal insufficiency. Use in pregnant females has not been evaluated.

Precautions:
Store at a controlled room temperature of 15°C to 30°C (59°F to 86°F).

Cautions:
The effects of levothyroxine sodium therapy are slow in being manifested. Overdosage of any thyroid drug may produce the signs and symptoms of thyrotoxicosis including, but not limited to: Polydipsia, polyuria, polyphagia, reduced heat tolerance and hyperactivity or personality change. Administer with caution to animals with clinically significant heart disease, hypertension or other complications for which a sharply increased metabolic rate might prove hazardous.

Side Effects:
There are no particular adverse reactions associated with levothyroxine sodium therapy at the recommended dosage levels. Overdosage will result in the signs of thyrotoxicosis listed above under Cautions.

Discussion:
Canine hypothyroidism is usually primary, i.e., due to atrophy of the thyroid gland. In the majority of cases the atrophy is associated with lymphocytic thyroiditis and in the remainder it is non-inflammatory and yet of unknown etiology. Less than 10 percent of cases of hypothyroidism are secondary, i.e., due to deficiency of thyroid stimulating hormone (TSH). TSH deficiency may occur as a component of congenital hypopituitarism or as an acquired disorder in adult dogs, in which case it is invariably due to the growth of a pituitary tumor.
Hypothyroidism usually occurs in middle-aged and older dogs although the condition will sometimes be seen in younger dogs of the larger breeds. Neutered animals of either sex are also frequently affected, regardless of age. The following are clinical signs of hypothyroidism in dogs: Lethargy, lack of endurance, increased sleeping, reduced interest, alertness and excitability, slow heart rate, weak apex beat and pulse, low voltage on ECG, preference for warmth, low body temperature, cool skin, increased body weight, stiff and slow movements, dragging of front feet, head tilt, disturbed balance, unilateral facial paralysis, atrophy of epidermis, thickening of dermis, surface and follicular hyperkeratosis, pigmentation, puffy face, blepharoptosis, tragic expression, dry, coarse, sparse coat, slow regrowth after clipping, retarded turnover of hair (carpet coat of boxers), shortening or absence of estrus, lack of libido, dry feces, occasional diarrhea, hypercholesterolemia, normochromic, normocytic anemia, elevated serum creatinine phosphokinase.