Fluoroquinolones Pharmacology PDF

STUDENT LOGIN Our Pharmacy Blog Antimicrobial Drugs General Pharmacology Fluoroquinolones Pharmacology! Jul 30th, 2023 Fluoroquinolones Pharmacology Quinolones have been around since the 1960s – with the introduction of nalidixic acid to treat urinary tract infections. Most quinolones...

STUDENT LOGIN Our Pharmacy Blog Antimicrobial Drugs General Pharmacology Fluoroquinolones Pharmacology! Jul 30th, 2023 Fluoroquinolones Pharmacology Quinolones have been around since the 1960s – with the introduction of nalidixic acid to treat urinary tract infections. Most quinolones in modern use are fluoroquinolones – examples of which include ciprofloxacin and moxifloxacin. Fluoroquinolones are broad-spectrum antibacterial agents – used to treat a variety of Gram-positive and Gram-negative infections. However, they are most effective at treating infections caused by aerobic, Gram-negative bacteria. Fluoroquinolones are used to treat infections such as: Urinary tract infections (UTIs)  Lower respiratory tract infections (moxifloxacin, levofloxacin preferred) Gastrointestinal infections – Shigella, campylobacter Pseudomonas aeruginosa – (ciprofloxacin and levofloxacin are both effective) Nosocomial infections associated with urinary catheters Examples of commonly prescribed fluoroquinolones include: Ciprofloxacin Moxifloxacin Levofloxacin Ofloxacin Norfloxacin Below, we talk about fluoroquinolones pharmacology in more detail; explaining how they work to exert their therapeutic effect. Mechanism of Action Fluoroquinolones work by interfering with DNA replication. More specifically, fluoroquinolones work by inhibiting DNA gyrase or topoisomerase IV – inhibiting the DNA replication and transcription processes. Earlier quinolones have more activity against topoisomerase II, whereas later generation quinolones have more activity against topoisomerase IV. Later fluoroquinolones – such as levofloxacin and moxifloxacin – also have more activity against Gram-positive organisms compared to earlier quinolones, such as ciprofloxacin. There are three primary mechanisms of bacterial resistance. Fluoroquinolones are known for the rapid onset of resistance. These mechanisms include: Efflux pumps Plasmid-mediated resistance Mutations in DNA gyrase / topoisomerase IV Due to the risk of developing quick resistance, fluoroquinolones are frequently reserved as second and third-line treatment for a wide variety of infections. Side Effects Fluoroquinolones are associated with their own range of potential side effects. Side effects with fluoroquinolones include: Gastrointestinal effects – nausea, abdominal pain, diarrhea Headache Lowering the seizure threshold Tendonitis and tendon rupture QT prolongation – moxifloxacin most associated with this Clostridium difficile colitis Though fluoroquinolones are associated with the above side effects, they are generally well-tolerated – at least at a comparable rate to other antibacterial classes.  Recent studies have shed light on the relationship between fluoroquinolones and tendon rupture. For instance, a Japanese study showed that third-generation fluoroquinolones (such as moxifloxacin) were not associated with tendon rupture compared to the first two generations. Clinical Pharmacology When we talk about the clinical pharmacology of fluoroquinolones, we need to think about the following factors: Fluoroquinolones should be used with caution in patients with epilepsy or in patients at an increased risk of seizures. Fluoroquinolones should be used with caution in patients with either cardiovascular disease or electrolyte disturbances – both of which increase the risk of QT prolongation. Fluoroquinolones should be used with caution in patients taking drugs that can prolong the QT interval – such as SSRIs, antipsychotics, quinine, macrolide antibacterial drugs and amiodarone. Fluoroquinolones interact with multivalent ions – for example: magnesium or aluminum ions present in antacids or other medicines. They also interact with calcium, iron or zinc-containing products, supplements or medicines – reducing activity of fluoroquinolones. NSAIDs, when taken with fluoroquinolones, increase the risk of seizures. Prednisolone, when taken with fluoroquinolones, increases the risk of tendonitis or tendon rupture. Fluoroquinolones should be used with caution in patients who are still growing or developing – as it increases the risk of arthopathy and other damage to the musculoskeletal system. Ciprofloxacin is contraindicated in patients taking the muscle relaxant, tizanidine – as the combination can lead to significant respiratory depression. Ciprofloxacin is an inhibitor of CYP1A2, the enzyme that metabolises tizanidine. Other drug substrates of CYP1A2 include theophylline, clozapine, methylxanthines and olanzapine. Fluoroquinolones will, despite the ongoing threat of resistance, remain an important drug class in the clinician’s toolkit. That concludes our review of fluoroquinolones pharmacology. Check back to our pharmacy blog soon for more exclusive content to help you master the science of drugs and medicines!  Post Views: 6,848 SHARE Category Anticancer Pharmacology Antimicrobial Drugs Cardiovascular Pharmacology Clinical Case Study Clinical Pharmacy General Pharmacology GI Pharmacology Immune System Pharmacology Nervous System Pharmacology Respiratory Pharmacology Study Tips and Tricks Join Our Mailing List FOR EVEN MORE FACTS! 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