Aminoglycosides

Aminoglycosides

1. Definition, origin and place in MD pharmacology

• Aminoglycosides are a family of natural and semisynthetic bactericidal antibiotics characterised by amino sugars linked glycosidically to a central aminocyclitol ring (streptidine in streptomycin; 2-deoxystreptamine in all others) (G&G 14e Ch.59, pp 1167; KDT 8e Ch.54, p 793; Katzung 16e Ch.45, p 868).
• They are produced principally by soil actinomycetes:
  • Streptomyces spp. yield drugs with the -mycin suffix — streptomycin (S. griseus), kanamycin, tobramycin (S. tenebrarius), neomycin (S. fradiae), framycetin (S. lavendulae), paromomycin.
  • Micromonospora spp. yield drugs with the -micin spelling variant — gentamicin (M. purpurea), sisomicin (M. inyoensis), netilmicin (semisynthetic from sisomicin).
  • Semisynthetic derivatives: amikacin (from kanamycin), netilmicin (from sisomicin), plazomicin (from sisomicin), arbekacin (Japanese kanamycin derivative, MRSA-active) (G&G 14e Ch.59, p 1167; KDT 8e Ch.54, p 800; Katzung 16e Ch.45, p 868).
• Historical anchor: streptomycin (Waksman, 1944) — first member discovered; tuberculosis was its defining indication; gentamicin (1964) is the most widely used systemic aminoglycoside (KDT 8e Ch.54, p 793; Katzung 16e Ch.45, p 868).
• The spelling difference -mycin vs -micin reflects organism of origin only — not a pharmacological distinction (G&G 14e Ch.59, p 1167).
• Aminoglycosides remain a high-yield MD topic because they are the prototypical concentration-dependent bactericidal antibiotics AND the prototypical narrow-therapeutic-index drugs requiring therapeutic drug monitoring (TDM) — almost every pharmacokinetic principle (compartment modelling, Cockcroft-Gault dosing, extended-interval regimens, post-antibiotic effect, AUC₂₄ targeting, dialysis dosing) was codified for this class (Concepts 7e L12, pp 175–201; Winter 6e Ch.6, pp 163–201).