Oroxine Dosage/Direction for Use

Posology: General: If the dose of levothyroxine is increased too rapidly, symptoms such as diarrhoea, nervousness, rapid pulse, insomnia, tremors and sometimes anginal pain where there is latent myocardial ischemia may occur, and the dosage must be reduced or withheld for a day or two, then restarted at a lower level. A pre-therapy ECG is valuable, as changes induced by hypothyroidism may be confused with ECG evidence of ischemia.
Due to a lack of data it is not appropriate to crush levothyroxine tablets and levothyroxine tablets without a score-line must not be halved.
Levothyroxine tablets should preferably be taken on an empty stomach.
Missed Dosage: If a scheduled daily dose is missed, the dose should be taken as soon as the patient remembers, unless it is almost time for the patient's next dose. Two doses should not be taken together.
Interactions: In patients whose medications include levothyroxine and known interfering agents, administration should be separated by at least 4 hours.
Populations: Adults: Initially 50 to 100 micrograms daily, and adjusted at 4 to 6 week intervals by 50 micrograms until attainment of clinical and biochemical euthyroidism. This may require doses of 100 to 200 micrograms daily.
With patients aged over 50 years, it is not advisable to exceed 50 micrograms a day initially. Where there is cardiac disease, 50 micrograms on alternate days is more suitable. In this condition the daily dosage may be increased by 50 micrograms on alternate days, at intervals of approximately 4 weeks.
Children: In congenital hypothyroidism and juvenile myxoedema, the largest dose consistent with freedom from toxic effects should be given. The dosage is guided by clinical response, growth assessment and appropriate thyroid function tests - clinically normal pulse rate and absence of diarrhoea or constipation are the most useful indicators. Thyrotrophin levels may remain elevated during the first year of life in children with neonatal hypothyroidism due to resetting of the hypothalamic-pituitary axis.
For infants with congenital hypothyroidism, a suitable starting dose is 50 micrograms levothyroxine sodium on alternate days, with increments of 50 micrograms on alternate days at intervals of every 2 to 4 weeks until optimal response is achieved. The same dosing regimen applies to juvenile myxoedema, except that the starting dose for children older than one year may be 2.5 to 5 micrograms/kg/day. The calculated daily dose equivalent should be rounded to the nearest 25 micrograms to determine the actual prescribed dose.