Q: Doxycycline being a tetracycline needs to be adjusted in renal dysfunction?
This is true for most of the tetracyclines that they get eliminated via renal route and need adjustment in renal insufficiency. Doxycycline is one of the tetracyclines which gets 80 percent excreted in the feces via bile. Tigecycline is another tetracycline that does not require adjustment in the renal insufficiency.
Tetracyclines are usually contraindicated in children due to their tendency to cause tooth discoloration and bony growth retardation. Doxycycline is one unique tetracycline that can be used in children less than eight years of age. Also it can be used in pregnant and breastfeeding females if required.
Vojtová V, Urbánek K. Farmakokinetika tetracyklinů a glycylcyklinů [Pharmacokinetics of tetracyclines and glycylcyclines]. Klin Mikrobiol Infekc Lek. 2009 Feb;15(1):17-21. Czech. PMID: 19399726.