PSA - drugs Flashcards
Name 3 weak opioids
codeine, dihydrocodeine, tramadol
What are the clinical implications for weak opioids?
Mild to moderate pain
Diarrhoea
Cough suppression
Prescribing doses and frequency for weak opioids used to manage pain
30-60mg every 4 hours as required (maximum 240mg daily)
Common adverse effects of weak opioids?
Constipation, biliary/ureteric spasm, dysphoria, sweating
Nausea/vomiting, drowsiness
Important adverse effects of weak opioids?
Respiratory depression (high doses) Hypotension (high doses) Paralytic ileus (dihydrocodeine)
In who should you avoid using weak opioids?
Avoid in COPD, acute asthma attack, acute respiratory depression, comatose patients and those at risk of paralytic ileus
What do weak opioids interact with?
CNS depressants (increased risk of respiratory depression) – alcohol, sedatives, hypnotics, general anaesthetics
What do you need to communicate to the patient when prescribing weak opioids?
Explain to patients that this medication could cause them to feel drowsy and that if this happens they should not drive or operate machinery. Patients should also be advised to avoid drinking alcohol while taking this medication
Name a few strong opioids
Buprenorphine, diamorphine, fentanyl, methadone,
oxycodone
Clinical indications for strong opioids?
Moderate to severe pain (including use in palliative care)
Acute diarrhoea (not first line)
Cough in terminal care
Dose and frequency of morphine administration
Morphine: 10mg s/c or IM every 4 hours (5mg every 4 hours if elderly, reduce dose in hepatic or renal impairment) , adjust according to response
Can also be administered by syringe driver or patient controlled analgesia (PCA) system
Adverse effects of strong opioids (same as weak)
Constipation, biliary/ureteric spasm, dysphoria, sweating
Nausea/vomiting, drowsiness
Important adverse effects of strong opioids
Respiratory depression Hypotension Sedation and coma Tolerance Physical and psychological dependence Overdose – this is reversed with naloxone
Who to avoid use of strong opioids in?
Avoid in acute respiratory depression, coma, head injury or raised ICP (opioids interfere with pupillary responses used in neurological assessment) and those at risk of paralytic ileus
What interacts with strong opioids?
CNS depressants (increased risk of respiratory depression) – alcohol, sedatives, hypnotics, general anaesthetics MAOIs (potentiate action of morphine)
What do you need to communicate to the patient when prescribing strong opioids? (same as weak)
Explain to patients that this medication could cause them to feel drowsy and that if this happens they should not drive or operate machinery. Patients should also be advised to avoid drinking alcohol while taking this medication.
Name two LMWHs
Dalteparin, Tinzaparin
What is the mechanism of action of LMWHs?
LMWH binds to antithrombin 3 and accelerates its action: Inhibition of factor Xa in the common pathway of the clotting cascade
Factor Xa is needed to convert prothrombin to thrombin, therefore LMWHs inhibit coagulation
What are the clinical indications for LMWHs?
Prophylaxis of venous thromboembolism (VTE)
Treatment of VTE before adequate oral anticoagulation (with warfarin) is established
Treatment of acute MI and unstable coronary artery disease, PE, DVT
Important adverse effects of LMWHs?
Haemorrhage
Heparin-induced thrombocytopenia (discontinue in these patients)
Hyperkalaemia
Who should you avoid giving LMWHs to?
Avoid in haemophilia and other haemorrhagic disorders, thrombocytopenia, recent cerebral haemorrhage, severe hypertension, peptic ulcer disease, acute bacterial endocarditis, following major trauma and in patients with known hypersensitivity to heparins
What do LMWH interact with?
NSAIDs (increased risk of haemorrhage)
ACE inhibitors, ARBs (increased risk of hyperkalaemia)
Antiplatelet agents (increased risk of haemorrhage)
What do you need to advise the patient of when taking LMWHs?
Advise the patient to avoid OTC NSAIDS
What type of drug is Warfarin?
Vit K competitive inhibitor
Depletion of active clotting factors II, VII, IX and X
The onset of warfarin’s anticoagulant effect is delayed for several days until already formed active clotting factors have been degraded
Clinical indications for Warfarin
Prophylaxis of embolisation in rheumatic heart disease and AF
Prophylaxis after insertion of prosthetic heart valve
Prophylaxis and treatment of VT and PE
Transient ischaemic attack (TIA)
What are the usual doses for Warfarin?
Loading dose 5-10mg
Daily maintenance dose 3-9mg at the same time each day
Dose depends on patient’s prothrombin time (INR), wide interindividual variation in dose
Common adverse effects of Warfarin?
Haemorrhage and bruising
Important adverse effects of Warfarin?
Skin necrosis, hypersensitivity, liver dysfunction, jaundice, pyrexia
Who should you avoid giving Warfarin to?
Avoid in pregnancy, peptic ulcer disease, severe hypertension and those with hepatic impairment (especially if prothrombin time already prolonged)
How do you monitor Warfarin?
Regular INR - begin with daily/alternate days
Can extend up to 12 week intervals
What do you need to communicate to the patient?
Do not take ASPIRIN without speaking to pharmacist
Use contraception - warfarin is damaging to pregnancy
Avoid cranberry juice, major diet changes (leafy veg), excess alcohol
Take Warfarin at the same time each day
Attend appts for INR checks
Additional Warfarin notes
As the onset of the anticoagulant effect of Warfarin is delayed by several days, patients should be given a LMWH to cover them during this period
What enhances the effect of Warfarin?
Alcohol
NSAIDs incl. aspirin
Anti-arrhythmics - amiodarone etc
Antibacterials – chloramphenicol, ciprofloxacin, co-trimoxazole, erythromycin, metronidazole, ofloxacin and sulphonamides
Experience from anticoagulant clinics suggests that any broad-spectrum antibiotic, especially ampicillin, can increase the INR
Antifungals – fluconazole, itraconazole, ketoconazole, miconazole
Lipid-lowering drugs – fibrates and simvastatin
Ulcer-healing drugs – cimetidine, omeprazole
What reduces the effect of Warfarin?
Antiepileptics – carbamazepine, primidone, phenytoin
Antifungals – griseofulvin
oCP
Vitamin K – high intake of vitamin K can counteract warfarin activity
Retinoids – acitretin
Antidepressants – St. John’s Wort
What is Rivaroxaban and what is its MoA?
Factor Xa inhibitor
Inhibits activated factor Xa, which is required for the conversion of prothrombin to thrombin in the common pathway of the coagulation cascade
Lack of thrombin prevents conversion of fibrinogen to fibrin and therefore inhibits thrombus formation
What is the clinical indication of Rivaroxaban?
Prophylaxis of venous thromboembolism (VTE) following hip/knee replacement surgery Treatment of DVT & prophylaxis of recurrent DVT & PE
What dose of Rivaroxaban/Dabigatran?
Rivaroxaban – 10mg once daily for 2 weeks after knee replacement (5 weeks after hip replacement)
Dabigatran – 220mg once daily for 9 days after knee replacement (27-34 days after hip replacement) Reduce dose in renal impairment
Common adverse effects of Rivaroxaban?
Haemorrhage (no reversal agent liscensed at present)
Abdominal pain; constipation; diarrhoea; dizziness; dyspepsia;
headache; hypotension; nausea; pain in extremities; pruritus; rash; renal impairment; vomiting
Important adverse effects of Dabigatran?
Hepatobiliary disorders (dabigatran)
Interactions of Rivaroxaban?
NSAIDs (increased risk of bleeding) Amiodarone (increased plasma dabigatran concentration – reduce dose of dabigatran) Verapamil (increased plasma dabigatran concentration – reduce dose of dabigatran) Triazole antifungals (avoid combination with rivaroxaban)
Additional notes for NOACs
These novel anticoagulants have a much broader therapeutic index than the traditionally-used oral anticoagulant warfarin – this allows for fixed drug dosing without the need for coagulation monitoring. However, at present no specific antidotes to these drugs exist.
Tablets should be taken with food.
What type of drug is aspirin?
Antiplatelet
What is the MoA of aspirin?
COX enzyme inhibitor
Impairs synthesis of thromboxane A2 + prostacyclin within plts
Clinical indication for aspirin
Secondary prevention of CVD after MI/ACS/stroke
Dose of aspirin?
75mg OD
Important adverse effects of aspirin?
GI irritation, ulceration and breathing
Bronchospasm
CI of aspirin?
Avoid in active peptic ulcer, haemophilia, known hypersensitivity
Interactions with aspirin?
Increased bleeding risk with:
NSAIDs, anticoagulants, SSRIs
What is clopidogrel?
Antiplatelet
What is the MoA of clopidogrel?
Inhibits binding of ADP to its platelet receptor
Clinical indications for clopidogrel use?
Secondary prevention of atherothrombotic event - following MI/stroke/PAD
With aspirin in ACS + for 1yr following coronary artery procedures
Doses of clopidogrel?
Secondary prevention following MI/stroke: 75mg once daily Acute coronary syndrome: Loading dose – 300-600mg
Maintenance dose – 75mg daily
Common adverse effects of clopidogrel?
GI disturbance, bleeding disorders
Important adverse effects of clopidogrel?
gastric + duodenal ulcers
Who should avoid using clopidogrel?
Pregnant women, active bleeding, discontinue for 7 days before elective surgery
What interacts with clopidogrel?
Increased risk of bleeding: other antiplatelet drugs, anticoagulants, fibrinolytic, NSAIDs
Decreased risk: ulcer healing drugs
