3 Managing the Risk of Prescribing Flashcards
What is Diltiazem?
Calcium channel blocker
Which calcium channel blocker interacts with simvastatin?
Diltiazem
How would you manage rhabdomyolysis in statin
- Stop statin
- Renal failure - dialysis
- IV fluids - prevent renal failure
- Sodium bicarbonate - alkalinize urine
- Monitr serum potassium
What is the definition of an adverse drug reaction?
Use of a medicial product within the term of the marketing authorisation as well as from use outside the terms of the marketing authorisation, including overdose, miuse, abuse and medication errors, and suspected adverse reactions associated with occupational exposure
What is an adverse event and adverse drug reaction?
Event - any harmful or unpleasant event that hte patient experiences while using a drug, whether or not it is related to the drug
Reaction - adverse event where it is suspected to be caused by the drug
What is a type A drug reaction?
What are some examples?
Type A (augmented) reactions are ones that are generally:
- Dose-related
- Common, predictable
- Related to the pharmacology
- Unlikely to be fatal
Digoxin toxicity or constipation with opioid analgesics
What is a type B drug reaction?
What are some examples?
Type B (bizarre) reactions are generally:
- Not dose-related (within the therapeutic dose range)
- Uncommon, unpredictable
- Not related to the pharmacology
- Often fatal
Penicillin hypersensitivity, and malignant hyperthermia and hepatitis caused by anaesthetic agents
What is type C drug reaction?
What are some examples?
Type C - Chronic
- Uncommon
- Related to cumulative dose
- Time-related
Suppression to the hypothalamic pituitary adrenal axis with long-term cotricosteroids
What is a type D drug reaction?
What are some examples?
Type D - Delayed
- Uncommon
- Usually dose-related
- Occurs or becomes apparent some time after use of the drug
Carcinogenesis
What is a type E drug reaction?
What is an example of this?
Type E - End of treatment
- Uncommon
- Occurs son after withdrawal of the drug
Opiate withdrawal syndrome
What is type F drug reaction?
What are some examples?
Type F - Failure
- Common
- Dose-related
- Often caused by drug interactions
Failure of the oral contraceptive in the presence of an enzyme inducer
Failure of therapeutic effect in patients taking anticoagulants leading to stroke
What does DoTS stand for?
What can ARDS be divided into due to DoTS?
- Dose
- Timing
- Susceptability
- Hypersusceptability reactions
- Collateral effects
- Toxic effects
What can ARDS be seperated into?
- Time dependent
- Time independent
What factors make you susceptable to an ADR?
- Immunological reactions
- Genetics
- Age
- Sex
- Physiology
- Exogenous
- Disease states affecting the patient
What diseases increase the risk of ADRs?
- Congestive cardiac failure
- Diabetes mellitus
- Chronic pulmonary disease
- Rheumatological and malignant disease
What coniditons happen more in females?
- Psychiatric adverse effects with the anti-malarial mefloquine
- Drug-induced torsade de pointes, linked to ventricular fibrillation and death. Women have an intrinsically longer QT interval than men
- Hyponatraemia with diuretics
What ethnic factors influence ADRs?
- Europeans metabolise warfarin differently
- Afro-carribeans have an increased risk of angioedema with the use of ACE inhibitors
- Chinese and Japanese origin are less likely to suffer psychiatric adverse effects from mefloquine
- Rosuvastatin altered in patinets of Asian origin, which may increase their risk of myopathy
What drugs increase the risk and severity of haemolysis with G6PD?
- Anti-malarials (primaquine)
- Nitrofurantoin
- Quinolone antimicrobials (ciprofloxacin)
- Rasburicase
- Sulphonamides (co-trimoxazole)
What is a main side effect of Clozapine?
Agranulocytosis
Monitor white blood cells
What does the yellow card shceme collect data on>
Both licensed and unlicensed medicines including:
- Prescription medicines
- Vaccines
- Over-the-counter medicines
- Herbal remedies
What percentage of the population to VERY COMMON ADRs occur in?
10%
What percentage of the population to COMMON ADRs occur in?
More than 1% but less than 10% of patients
What percentage of the population to UNCOMMON ADRs occur in?
more than 0.1% but less than 1% of patients
What percentage of the population to RARE ADRs occur in?
More than 0.01% but less than 0.1% of patients
What is the interaction between warfarin and miconazole?
- Miconazole inhibits a cytochrome P450 enzyme.
- This enzyme metabolises warfarin.
- Therefore more warfarin
Who elimates drugs more rapidly from their body female or males?
Females
What adverse effect are females more at risk of?
Torsades des points and some severe idiosyncratic (no kown cause) drug reactions
In which ethnic group is clopidogrel much less likely to be cleared?
Chinese/Japanese/Korean ancestry
What drugs can alcohol interact with?
- Warfarin
- Metronidazole
What syndrome can amfetamines lead to?
Seotonin syndrome
What happens in a pharmacodynamic interaction?
Drugs amplify or negate each other’s pharmacological effects
What are pharmacokinetic interactions?
When one drug, dietary or herbal chemical, impacts on the biotransformation of a drug, or even their distribution within the body
What is an example of two drugs that cause a pharmacodynamic interaction?
Sildenafil and glyceryl trinitrate
Severe hypotension or MI
What foods interact with Warfarin?
Leafy vegetables containing vitamin K
What foods can interact with ACE inhibitors?
If people have swapped their dietary salt for potassium-containing salt may be at risk of hyperkalaemia.
What drugs does grapefruit juice interact with?
- Calcium-channel blockers
- Statins
- Immunosuppressants
- Anti-arrhythmics
What kind of reaction is aminoglycoside and loop diuretic?
- Pharacodynamic interaction
- Both cause ototoxicity
What type of reaction is lithium salts and ramipril?
- Pharmacokinetic interaction
- ACE inhibitors reduce the GFR and increase sodium loss, which is linked with their promotion of lithium retention.
What is the interaction of rifampicin and the combined oral contraceptive?
- Pharmacokinetic interaction
- Rifampicin induces drug metabolising enzymes in the liver, cytochrome P450
- This reduces the effectiveness of both oestrogens and progestogens.
What is the reaction between verapamil and beta-blockers?
- Pharmacodynamic interaction
- They both have similar pharmacological effects, additive effects
What is the interaction between warfarin and NSAIDs?
- Pharmacodynamic interaction
- NSAIDS inhbit COX-1 and therefore production of protective prostaglandins.
- This increases the risk of bleeding
What is the interaction between warfarin and some macrolide antibacterials?
- Pharmacokinetic interaction
- Warfarin is metabolised by CYP3A4, so a reduction in CYP3A4 activity can reduce the metabolism of warfarin and therefore increase its concentration
When giving emergency contraception i.e levonorgestrel, what dose should be given in a woman taking carbamazepine?
Double the dose as any cytochrome P450 induces reduce the concentration of progestogens.
What drugs use organic anion-transporting polypeptides (OATPs) to enter cells?
Atorvastatin and fexofenadine
What drugs inhibit OATPs?
How does this effect atorvastatin?
- Rifampicin
Means atorvastatin does not enter first pass motabolism and increases its concentration
Which drugs are CYP inducers?
- Rifampicin
- St John’s Wort
- First gen anticonvulsants (phenytoin, carbamazepine and phenobarbital)
- Smoking
Which drugs are CYP inhibitors?
- Antigungals e.g. fluconazole, voriconazole
- Erythromycin
- Grapefruit juice
- Cranberry juice
What does garlic do?
Inhibits platelet aggregation
Caution with anticoagulants
What does Ginseng cause?
- Hypoglycaemic activity
What does Glucosamine interact with?
Warfarin
Increase INR
What does St John’s Wort interact with?
- Antidepressants - increase
- Warfarin - reduction in INR
- Oestrogen and progestogen - reduces contraceptive cover
What can liquorice cause?
- Hyperkalaemia - increase risk of digoxin toxicity
What does the concurrent use of methotrexate and folic acid do?
Reduce the adverse effects of therapy
What does oral iron do to the absorption of ciproflixacin?
- Redcues their absorption (all oral quinolone antibacterials)