Levothyroxine Indinavir

Levothyroxine is metabolized in part through the action of glucuronyl transferase, which can be inhibited by some antiretroviral drugs, such as indinavir. 

Lanzafame M, Trevenzoli M, Faggian F, Marcati P, Gatti F, Carolo G, Concia E. Interaction between levothyroxine and indinavir in a patient with HIV infection. Infection 2002 30(l) 54-5. 

THYROID HORMONES ANTIVIRALS - PROTEASE INHIBITORS 1 efficacy of levothyroxine by ritonavir (with or without lopinavir) and possibly indinavir and nelfinavir Uncertain possibly T metabolism via induction of glucuronosyl transferases Monitor thyroid function closely... 

Inhibition of glucuronyl transferase activity by indinavir has been blamed for an interaction of indinavir with levothyroxine, causing hyperthyroidism (43). 

A 36-year-old woman, who had taken levothyroxine for several years, took stavudine, lamivudine, and indinavir for I month and developed nervousness, palpitation, restlessness, weakness, and weight loss. She had an undetectable serum TSH concentration and raised unbound serum T4 and T3. The dose of levothyroxine was reduced to one-third and then to one-sixth of the previous dose, and the thyroid function tests returned to normal. 

A man needed to have his levothyroxine dosage doubled when he took ritonavir/saquinavir, and another woman possibly had a similar reaction when given indinavir then nelfinavir. Conversely, another woman needed a markedly reduced dose of levothyroxine when given indinavir. 

Conversely, in another woman a 4-week course of antiretroviral prophylaxis, including 2 weeks of indinavir then 2 weeks of nelfinavir, tended to reduce the efficacy of levothyroxine 125 micrograms daily. She was fatigued and had elevated TSH and hypercholesterolaemia, which resolved after the antiretroviral therapy was stopped. ... 

---