Metformin should be stopped following a myocardial infarction due to the risk of lactic acidosis. It may be introduced at a later date. Diabetic control may be achieved through the use of a insulin/dextrose infusion (e.g. the DIGAMI regime)
Azathioprine is a prodrug, meaning it is metabolised to its active form, 6-mercaptopurine, which causes immunosuppression (preventing kidney rejection in this patient). The active 6-mercaptopurine is subsequently metabolised by xanthine oxidase to inactive this uric acid which is excreted. As allopurinol inhibits xanthine oxidase, the combination of the two drugs can lead to excessive myelosuppression and therefore increase the risk of neutropenic sepsis.
Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) that can increase the risk of cardiovascular events, especially in patients with a history of cerebrovascular disease.
Diclofenac is now contraindicated with any form of cardiovascular disease
Quinine can cause drug-induced thrombocytopaenia
The risk of peripheral neuropathy with isoniazid can be reduced by prescribing pyridoxine
Ethambutol
mechanism of action: inhibits the enzyme arabinosyl transferase which polymerizes arabinose into arabinan
optic neuritis: check visual acuity before and during treatment
Amiodarone frequently causes abnormalities in thyroid function tests and may cause both hypothyroidism and hyperthyroidism.
Ciprofloxacin.Ciprofloxacin, a fluoroquinolone, is known to lower the seizure threshold in patients with a history of epilepsy.
An important major side effect of trastuzumab (Herceptin) is cardiomyopathy. Therefore patients prescribed trastuzumab require monitoring of left ventricular ejection fraction through serial echocardiograms before and during treatment.
Varenicline works as a nicotinic receptor partial agonist. It selectively binds to α4β2 nicotinic acetylcholine receptors in the brain, thereby reducing the pleasure and satisfaction associated with smoking
Lithium can cause cardiac foetal abnormalities - Ebstein’s anomaly
‘Grey baby’ syndrome is associated with chloramphenicol.
Craniofacial abnormalities are associated with ACE inhibitors, alcohol, carbamazepine, valproate and warfarin.
Neural tube defects are associated with carbamazepine and valproate.
Ototoxicity is associated with aminoglycosides.
Benzodiazepines - Flumazenil
The majority of overdoses are managed with supportive care only due to the risk of seizures with flumazenil. It is generally only used with severe or iatrogenic overdoses.
Ototoxicity is an important side effect of the aminoglycoside antibiotics, which include gentamicin, neomycin, and tobramycin. Neomycin is the aminoglycoside that is most ototoxic
According to UK guidelines, mefloquine should not be prescribed for individuals with a history of psychiatric disorders including anxiety and depression.
St John’s Wort is an inducers of the P450 enzyme system in the liver. This results in the combined oral contraceptive pill being metabolised faster and hence may reduce effectiveness.
Carbamazepine is an inducer of the P450 system. This in turn increases the metabolism of carbamazepine itself - auto-induction
Bupropion should not be used in a patient with epilepsy as it reduces seizure threshold
Bupropion, an atypical antidepressant used for smoking cessation, lowers the seizure threshold and hence is contraindicated in patients with epilepsy. The use of bupropion in these patients could potentially trigger a seizure episode.
Amiodarone therapy can result in both corneal opacities and optic neuritis
The combination of erythromycin with simvastatin significantly increases the risk of statin-induced myopathy and potentially life-threatening rhabdomyolysis. Furthermore, erythromycin can interact with amiodarone, potentially prolonging the QT interval and increasing the risk of dangerous arrhythmias.
Methotrexate can cause pneumonitis, an interstitial lung disease characterised by inflammation and fibrosis of the lung parenchyma.
Drugs causing lung fibrosis
Causes
amiodarone
cytotoxic agents: busulphan, bleomycin
anti-rheumatoid drugs: methotrexate, sulfasalazine
nitrofurantoin
ergot-derived dopamine receptor agonists (bromocriptine, cabergoline, pergolide)
Nicorandil, is a potassium channel activator with a nitrate component. The concurrent use of sildenafil and nicorandil can lead to an excessive drop in blood pressure due to their combined vasodilatory effects.
Diarrhoea is the major dose-limiting side effect of*****
magnesium salts
Visual changes secondary to drugs
blue vision:
Viagra (‘the blue pill’)
yellow-green vision: digoxin
Drugs to avoid in renal failure
antibiotics:
tetracycline, nitrofurantoin
NSAIDs
lithium
metformin
