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Efecto del carbonato de calcio en la absorción de la levotiroxina
N Singh1, P N Singh, J M Hershman
1Division of Endocrinology and Metabolism, Endocrinology 111D, VA Greater Los Angeles Healthcare System, 11301 Wilshire Blvd, Los Angeles, CA 90073. nsingh@ucla.edu
JAMA
|June 6, 2000
Resumen
El carbonato de calcio reduce significativamente la absorción de levotiroxina, lo que lleva a un aumento de los niveles de tirotropina en los pacientes. Esta interacción, debido a la adsorción de levotiroxina al carbonato de calcio, puede afectar la terapia de reemplazo de la hormona tiroidea.
Área de la Ciencia:
- Endocrinología Endocrinología.
- Farmacología Farmacología.
- Interacciones farmacológicas Interacciones farmacológicas
Sus antecedentes:
- El uso simultáneo de carbonato de calcio y levotiroxina es común, especialmente en mujeres posmenopáusicas.
- Faltan estudios sistemáticos sobre la interacción entre el carbonato de calcio y la absorción de levotiroxina.
- Las posibles interacciones farmacológicas merecen una investigación debido a la prescripción conjunta generalizada.
Objetivo del estudio:
- Para investigar la posible interferencia del carbonato de calcio en la absorción de la levotiroxina.
- Para evaluar el impacto del carbonato de calcio en los niveles de hormonas tiroideas.
- Comprender el mecanismo de interacción entre el carbonato de calcio y la levotiroxina.
Principales métodos:
- Estudio de cohorte prospectivo en el que participaron 20 pacientes con hipotiroidismo en tratamiento estable con levotiroxina.
- Estudio in vitro para evaluar la unión de la tiroxina (T4) al carbonato de calcio.
- Medición de los niveles de T4 libre, T4 total, triiodotironina total (T3) y tirotropina al inicio, durante la administración concomitante de carbonato de calcio y después de la interrupción del tratamiento.
Principales resultados:
- El carbonato de calcio redujo significativamente los niveles medios de T4 libre y T4 total.
- Los niveles medios de tirotropina aumentaron significativamente durante el uso de carbonato de calcio.
- Los estudios in vitro demostraron la adsorción de T4 al carbonato de calcio en condiciones ácidas, lo que sugiere un mecanismo de reducción de la biodisponibilidad.
Conclusiones:
- El carbonato de calcio reduce la absorción de levotiroxina y aumenta los niveles de tirotropina.
- La adsorción de levothyroxine al carbonato de calcio en un ambiente ácido puede disminuir su biodisponibilidad.
- Esta interacción requiere una cuidadosa consideración en pacientes que reciben tanto levotiroxina como carbonato de calcio.
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