University:
University College Cork
Course:
CK701 | MB, BCh, BAO (Hons)
Academic year:

2020
Views:

295

Pages:

4
Author:

Marianna B

FQs work by inhibiting nucleic acid transcription and replication Require a carboxylic acid at position 3, bicyclic system and a pyridone ring Nalidixic Acid  1st therapeutically useful agent in this class 1st Generation FQs 2nd Generation FQs 3rd Generation FQs What to look out for with FQs    Avoid metal containing drugs such as antacids o Beta keto acid functionality complexes with or chelates to metals in the 2+ ro 3+ oxidation state This can lead to treatment failure o Decreased absorption o Generally form an insoluble salt with Mg and Ca which cannot be absorbed by GIT Patient advised to avoid o Metal containing foods eg dairy, milk, cheese, tofu o Antacids o Multivitamins CNS side effects     Presence of piperazine ring is associated with increased risk of CNS side effects7 May experience o Dizziness o Headache o Rarely hallucinations o Delirium o Convulsions Drug has negative logP which is very poorly lipophilic and very unlikely to cross the BBB Binds GABA receptor which leads to these effects Theophylline    Drug-drug interaction with piperazine ring in 1st and 2nd FQs o Increases the conc in the blood This can lead to serious cardiac arrhythmia and convulsions o Dose of theophylline should be reduced or discontinued Piperazine ring in 1st and 2nd gen FQs is thought to bind to the CYP1A2 enzyme responsible for theophylline metabolism Renal effects    FQs can precipitate in the renal tubule o Painful o Potentially fatal crystalluria Patient advised to drink 1-2 glasses of water when taking Physiological pH is 7.4 o FQs can exist as zwitter ions at this pH o 93% in the zwitter ionic form o Decreased water solubility