Adverse Drug Reactions Flashcards
What is the effect of Amiodarone on Warfarin?
Amiodarone is an enzyme inhibitor leading to decreased clearance of Warfarin and consequently an increased INR.
What side effect is associated with beta blockers?
Insomnia is a commonly reported side effect of all beta blockers.
What are the well known side effects of Phenytoin?
Dupuytren’s contracture is a well recognised side effect of Phenytoin.
Other important SEs:
- Coarsening of facial features
- Hirsutism
- Gingival hyperplasia
- Tremor
- Vomiting
- Ataxia
- Peripheral neuropathy
What SE of cetirizine is most likely seen in children?
Drowsiness. Cetirizine is considered to be a non-drowsy antihistamine as it penetrates the blood brain barrier to a lesser extent than older antihistamine. Despite this, it can cause some drowsiness in children.
Which antibiotic should be given as an alternative to amoxicillin in penicillin allergic patients for a chest infection?
Clarithromycin (Macrolide).
Why is trimethoprim contraindicated with methotrexate?
Trimethoprim acts to block folate from being used in deoxyribonucleic acid (DNA) synthesis, as does methotrexate. Use of these two drugs together can cause bone marrow suppression and neutropenia. It is essential to monitor for any signs or symptoms of infection, such as sore throat and fever, in these patients for this reason.
What medications can cause erythema multiforme?
Erythema multiforme is an acute hypersensitivity reaction of the skin that results in classic target lesions (a rim of erythema surrounding a paler area and a vesicle or bullae).
Although 90% of cases are caused by infections (such as herpes simplex virus, human immunodeficiency virus and Mycoplasma), medications make up 10% of cases. Many drugs have been reported to cause erythema multiforme and this list includes:
- Penicillins
- NSAIDs
- Nitrofurantoin
- Sulfonamides
- Anticonvulsants.
Stevens-Johnson syndrome is a potentially fatal drug reaction that causes sheet-like skin and mucosal loss. It was previously thought to be a severe form of erythema multiforme, but it is now considered a distinct entity. It is nearly always caused by medications and 40% of cases are associated with antibiotics
Does steroids cause fluid retention?
Yes. Systemic corticosteroids can cause increased salt and water retention, especially when used in high doses. For this reason, they should be used with caution in patients who have pre-existing conditions such as heart failure or hypertension.
Over-treatment with exogenous corticosteroids can cause Cushing syndrome which presents with the characteristic features of truncal obesity, buffalo hump, moon facies and skin atrophy. It can also contribute to psychological problems such as depression.
Common side effects of steroids?
Common side-effects include:
- Fluid retention
- Abdominal pain
- indigestion
- feeling sick
- mood/behavioural changes
- difficulty sleeping
- feeling confused
- increased weight
- thrush
- muscle weakness
- feeling tired
- irregular periods.
SEs of memantine?
Memantine is a glutamate receptor antagonist. SEs include constipation, drowsiness, headache and hypertension. can also cause hallucinations and balance problems.
What medications cause anti-cholinergic SEs? (dry mouth, constipation, visual changes and urinary retention)
Tricyclic antidepressant (Amitryptiline)
Atropine
Oxybutynin
Ipratropium
What medication can cause bilateral ankle swelling?
Amlodipine. Peripheral oedema is a known SE of amlodipine. ACEi can be considered if SE not tolerated.
Most common SE caused by bisoprolol?
Headache and dizziness are common symptoms of bisoprolol use.
Bisoprolol is a selective inhibitor of beta-1 adrenergic receptors with little or no effect on beta-2 receptors. But can cause bronchospasm in reactive airways (asthma).
SE associated with entacapone (COMT inhibitor)?
Red-brown urine.
What is a SE of bleomycin?
Pulmonary fibrosis.
Common SE of gentamicin toxicity?
Vertigo.
Gentamicin is an intravenous (IV) aminoglycoside. The primary toxicities of aminoglycosides are nephrotoxicity and ototoxicity.
Aminoglycoside-induced ototoxicity may result in either vestibular or cochlear damage. Vestibular toxicity manifests as vertigo, light-headedness, nausea, vomiting and ataxia.
Cochlear toxicity manifests as tinnitus and bilateral sensorineural hearing loss. In many cases, ototoxicity is irreversible. Ototoxicity is more likely to occur with courses lasting more than one week but can occur irrespective of dose, blood concentration measurements and renal function. An audiogram should be considered if therapy is anticipated to continue for more than seven days.
What drug exacerbates Parkinsonian symptoms?
Metoclopramide. It is a dopamine antagonist which crosses the blood brain barrier. It can cause a reduction in dopamine level therefore exacerbating parkinson’s symptoms.
What adverse effect is likely caused by Seretide?
Oral candidiasis.
Seretide is a combination of fluticasone (corticosteroid) and salmeterol (LABA). Candidiases is a common SE of inhaled corticosteroids. The risk can be reduced by encouraging rinsing with water after using the inhaler and use of a spacer driver.
Common SE of codeine?
Constipation.
Codeine is thought to act on receptors in the gastrointestinal (GI) tract by inhibiting gastric emptying, delaying peristalsis and decreasing the amount of fluid available in the intestine. These effects contribute to the hardening of stool and increased difficulty in passing stool.
What drugs need to be used with caution in asthmatics?
- NSAIDs
- Beta blockers
- Adenosine
Around 10-20% of patients with asthma experience bronchospasm / worsening of asthma control after ingesting NSAIDs. The risk is increased in patients with nasal polyps and also those who are middle-aged. Surprisingly, NSAID-induced asthma is uncommon in children.
If alternative analgesics are not available and there is no history of hypersensitivity to NSAIDs it is acceptable to give asthmatic patients a trial of NSAIDs after informing them of the risks.
Again beta-blockers may cause bronchospasm and are best avoided. They are not however absolutely contraindicated and if no alternatives are available a low-dose may be initiated under specialist supervision. Some beta-blockers are more cardioselective (e.g. nebivolol) so in theory may induce less bronchospasm.
The BNF states that asthma / chronic obstructive pulmonary disease (COPD) are contra-indications to adenosine. Verapamil may be used as an alternative.
Caution should be exercised when prescribing large doses of opioid based medications on benzodiazipines to patients with COPD as these medications may act as respiratory depressants.
What drugs can exacerbate heart failure?
The following medications may exacerbate heart failure:
- Thiazolidinediones: Pioglitazone is contraindicated as it causes fluid retention
- Verapamil: negative inotropic effect
- NSAIDs/glucocorticoids: should be used with caution as they cause fluid retention.
low-dose aspirin is an exception; many patients will have coexistent cardiovascular disease and the benefits of taking aspirin easily outweigh the risks. - Class I antiarrhythmics: Flecainide (negative inotropic and proarrhythmic effect).
Drugs that worsen seizure control in epilepsy?
The following drugs may worsen seizure control in patients with epilepsy:
- alcohol, cocaine, amphetamines
- ciprofloxacin, levofloxacin
- aminophylline, theophylline
- bupropion
- methylphenidate (used in ADHD)
- mefenamic acid
Some medications such as benzodiazepines, baclofen and hydroxyzine may provoke seizures whilst they are being withdrawn.
Other medications may worsen seizure control by interfering with the metabolism of anti-epileptic drugs (i.e. P450 inducers/inhibitors).
Drugs harmful in pregnancy?
Antibiotics:
- tetracyclines
- aminoglycosides
- sulphonamides and trimethoprim
- quinolones
- ACE inhibitors, ARBs
- Statins
- Warfarin (Most women are switched to LMWH for the duration of the pregnancy)
- Sulfonylureas
- Retinoids (including topical)
- Cytotoxic agents
The majority of antiepileptics including valproate, carbamazepine and phenytoin are known to be potentially harmful. The decision to stop such treatments however is difficult as uncontrolled epilepsy is also a risk.
Regarding dosing of gentamicin, what should be done if the peak (post dose) level is high?
Due to the significant ototoxic and nephrotoxic potential of gentamicin it is important to monitor plasma concentrations.
Both peak (1 hour after administration) and trough levels (just before the next dose) are measured:
- If the trough (pre-dose) level is high the interval between the doses should be increased.
- If the peak (post-dose) level is high the dose should be decreased.
