Clinical pharmacology - Essay Example

2010). Antibiotics especially co-trimoxazole, metronidazole, macrolides, fluroquinolones: As far as sulpha drugs which cause enhanced effect of Warfarin resulting in bleeding, in the absence of proven mechanism of action, it has been hypothesized by clinicians that systematic administration of such antibiotics results in reduced production of Vitamin K caused by intestinal flora. Same mechanism of action applies to macrolides that include Azithromycin etc and quinolones such as ciprofloxacin (Medication Management Home).

As for metronidazole, it interferes with metabolism of S enatiomer of Warfarin. As for, Rifampin, it induces hepatic enzymes thus increasing metabolism of Warfarin (Horton and Bushwick, 1999). Antidepressants: Two theoretical hypotheses about Warfarin’s potential interactions with antidepressants are that because Warfarin is protein bound, antidepressants which are also protein bound, their interaction can result in displacement of Warfarin from its binding sites as stated by Sansone and Sansone (2009).

They at the same time point out the observation of Sayal et al (2000) that there is no clinical evidence to that effect. Selective Serotonin Reuptake Inhibitors (SSRIs), are found to potentially inhibit Warfarin metabolism through their isoenzymes 2C9 and 1A2. However Sertraline and Citalopran are not likely to cause interaction. While Paroxetine has low-to-moderate risk, fluvoxamine and fluoxetine have the potential to effects of Warfarin. Ginkgo biloba has properties capable of inhibiting platelet aggregation, if taken with Warfarin, it will enhance the toxic effects monamine oxidase inhibitors.

However, Ginkgo on its own is capable of causing bleeding complications (Dharmananda). Dong qual increases the anticoagulant action of Warfarin. St John’s Wort induces P450 pathways resulting in lowering of INR. This increases the metabolism of Warfarin.