Aminoglycosides exert a post-antibiotic effect: high peak levels are required to penetrate the bacterial cell wall, where the drug continues to have a bactericidal effect after systemic levels have declined. Monitoring is used to ensure adequacy of dosing, to delay or prevent the onset of nephrotoxicity and reduce the risk of vestibular and auditory ototoxicity.
Initial gentamicin dosing is based on bodyweight to ensure an adequate peak concentration.
Confusion surrounds the prescribing of antimicrobials in renal impairment; whether to reduce the dose or extend the dosing interval. Suggested dose adjustments in renal impairment for many commonly used antibiotics are provided here, based on tables which can be found in the Therapeutic Guidelines (TG) Antibiotic, 14th edition.
No dose adjustment is required for some agents – these include azithromycin, roxithromycin, ceftriaxone, cefaclor, clindamycin, doxycycline, linezolid, moxifloxacin, phenoxymethylpenicillin, metronidazole among others.
There is increasing concern about the lack of antibiotics in the research pipeline with more “superbugs” – resistant to many antibiotics – being discovered and many bacteria and viruses jumping from their original hosts to man.
Many countries – Australia included – are looking more closely at how antibiotics are used and also ensuring good hand hygiene – washing hands – between examining patients (doctors are the worst). When implemented in Australia this led to a decrease in the incidence of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia.
Just as important is the research carried on by non profit groups and government research. Australia is one of the world leaders with the worlds most advanced biosecure laboratory. The Australian Animal Health Laboratory in Geelong can research these new threats such as Hendra virus hopefully leading to new antibiotics (for bacteria) and new vaccines.
While alternative oral anticoagulant drugs such as dabigatran have recently been developed, warfarin is currently still the most commonly used and only PBS-listed oral anticoagulant in Australia for the prevention and treatment of thromboembolism in patients with mechanical heart valves, atrial fibrillation and deep vein thrombosis or pulmonary embolus. Warfarin exerts its therapeutic action as a vitamin K antagonist, lowering the amount of vitamin K available for the production of important clotting factors.