Macrólidos y cetólidos / Macrolides and ketolides

Los macrólidos y cetólidos son familias de antibióticos que comparten el mismo mecanismo de acción. Las dos se unen a distintas bases del centro peptidiltransferasa del ARNr 23S. Su espectro antibacteriano es prácticamente superponible; sin embargo, desigualdades en la afinidad y/o el número de lugares de unión determinan diferencias en la intensidad del efecto antibacteriano (bacteriostático/bactericida) y en la actividad contra cepas con mecanismos de resistencia adquiridos. Son activos contra la mayoría de los microorganismos grampositivos y muchos microorganismos de crecimiento intracelular. En nuestro país, durante los últimos 10 años el porcentaje de cepas de neumococo y Streptococcus pyogenes resistentes a los macrólidos ha aumentado sensiblemente. Telitromicina (cetólido) mantiene la actividad contra estas cepas. Se metabolizan en el hígado a través del CYP 3A4 y pueden inhibir parcialmente la actividad de la enzima, interfiriendo con el metabolismo de otros fármacos que emplean la misma vía metabólica. Apenas se eliminan con la orina (a excepción de claritromicina). Alcanzan concentraciones elevadas en el citoplasma celular, pero no difunden al líquido cefalorraquídeo. Se incluyen en la categoría B de fármacos empleables durante el embarazo. La tolerancia de los macrólidos es buena y los efectos secundarios son escasos. Su principal indicación clínica es el tratamiento empírico de infecciones de vías respiratorias altas y bajas, de intensidad leve o moderada, adquiridas en la comunidad. Algunos pacientes tratados con telitromicina han presentado cuadros de hepatitis grave, por lo que su empleo se ha limitado al tratamiento de la neumonía adquirida en la comunidad, en casos en que no se disponga de otra alternativa (AU)

Macrolides and ketolides are two families of antibiotics that share the same mechanism of action. They bind to different bases of the peptidyl transferase center of 23S RNA. The antibacterial spectrum of these drugs virtually overlaps, but dissimilarities in the affinity and number of binding sites results in differences in the intensity of their antibacterial effects (bacteriostatic or bactericidal) and their activity against strains with acquired resistance mechanisms. These agents are active against most gram-positive microorganisms and many intracellular microorganisms. Over the last ten years in Spain, the percentage of macrolide-resistant pneumococci and Streptococcus pyogenes strains has increased substantially. Telithromycin, a ketolide, has maintained the activity against these strains. Macrolides and ketolides are metabolized in the liver through CYP3A4 and they can partially block the activity of the enzyme, interfering with the metabolism of other drugs that use the same metabolic pathway. There is little elimination through the urine, with the exception of clarithromycin. High concentrations are reached in the cellular cytoplasm, but they do not diffuse to cerebrospinal fluid. These agents are included among class B drugs for use during pregnancy. Tolerance to macrolides is good and they have few associated adverse effects. The main clinical indication for these drugs is in empirical treatment of mild to moderate, community-acquired, upper and lower respiratory tract infections. Some patients treated with telithromycin developed severe hepatitis; therefore, its use is limited to community-acquired pneumonia in cases with no other available alternative (AU)

[Macrolides and ketolides]. / Macrólidos y cetólidos.

Macrolides and ketolides are two families of antibiotics that share the same mechanism of action. They bind to different bases of the peptidyl transferase center of 23S RNA. The antibacterial spectrum of these drugs virtually overlaps, but dissimilarities in the affinity and number of binding sites results in differences in the intensity of their antibacterial effects (bacteriostatic or bactericidal) and their activity against strains with acquired resistance mechanisms. These agents are active against most gram-positive microorganisms and many intracellular microorganisms. Over the last ten years in Spain, the percentage of macrolide-resistant pneumococci and Streptococcus pyogenes strains has increased substantially. Telithromycin, a ketolide, has maintained the activity against these strains. Macrolides and ketolides are metabolized in the liver through CYP3A4 and they can partially block the activity of the enzyme, interfering with the metabolism of other drugs that use the same metabolic pathway. There is little elimination through the urine, with the exception of clarithromycin. High concentrations are reached in the cellular cytoplasm, but they do not diffuse to cerebrospinal fluid. These agents are included among class B drugs for use during pregnancy. Tolerance to macrolides is good and they have few associated adverse effects. The main clinical indication for these drugs is in empirical treatment of mild to moderate, community-acquired, upper and lower respiratory tract infections. Some patients treated with telithromycin developed severe hepatitis; therefore, its use is limited to community-acquired pneumonia in cases with no other available alternative.