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McConnell et al., New York, NY, USA, measured total serum T4
and TSH prior and during administration of 1-1.5g salsalate daily to 5
(4 females) subjects with primary hypothyroidism. Prior and during salsalate
mean serum total T4 decreased from 9.01 ± 2.20 mcg/dl
to 6.7 ± 2.18 mcg/dl. The TSH values were 3.28 ± 2.89 mU/L
and 0.63 ± 1.14 mU/L respectively. These changes were seen as long
as salsalate was continued for a maximum period of 6 months. The authors
suggest that maybe the dose of T4 should be adjusted during
salsalate administration. (Comment: It would be wise to first further investigate
if the effect on TSH is a direct action at the level of the thyrotroph
before one should conclude that the dose administered should be changed.)
Wang et al., Loma Linda, CA, USA, studied the inhibitory activity of salsalate on T4 binding by the three major T4 binding proteins i.e. TTR, albumin, and TBG. In their experimental conditions a concentration of 1.52 mM salsalate was used and displacement of labeled T4 was evaluated at protein concentrations that were 2% of normal. A displacement of T4 tracer was found of 93% from TBG, 63% from albumin, and 58% from TTR. Furthermore, their studies showed that salsalate itself was primarily bound to albumin (86-92%) and only slightly bound to TBG and TTR (4-6%). |
