Prescribing and Pharmacology Flashcards
Action of ARBs and ACE-inhibitors
ARBs prevent the action of angiotensin II on receptors
ACE-i prevent the conversion of angiotensin I to angiotensin II
Reduce peripheral vascular resistance (afterload)
Especially dilates efferent glomerular arteriole, reducing pressure and slowing progression of CKD
Reduce aldosterone levels which promotes excretion of sodium and water via the kidneys - reduces venous return and therefore preload
Where is angiotensin converting enzyme released from
Lungs
Indications for ACE-inhibitors
- Hypertension: first/second-line treatment, reduces risk of CVD, stroke
- Chronic heart failure: first-line for all grades, improves symptoms and prognosis
- IHD
- Diabetic nephropathy and CKD with proteinuria
Adverse effects of ACE-inhibitors
Hypotension (especially after first dose)
Dry cough (due to high levels of bradykinin)
Hyperkalaemia (low aldosterone promotes potassium retention)
Renal failure (causes or worsens)
Angioedema and anaphylactoid reactions
Contraindications o ACE-inhibitors
AKI or renal stenosis
pregnancy or breastfeeding
Only in low doses if CKD
ACE-inhibitor interactions
Potassium elevating medications/fluids
NSAIDs: higher risk of renal failure
Tonsillitis treatment
Phenoxymethylpenicillin 10 days
Clarithromycin if penicillin allergy
What should you assess when completing a medication review?
What is the indication for each drug
Drug interactions
Contraindications
Suitability of each drug given current presentation (risks and benefits)
Important amitriptyline side effects
Antimuscarinic: dry mouth, constipation, blurred vision
H1 and a1: hypotension and sedation
Cardiac: arrhythmias, prolonged QT/QRS
Neurological: convulsions, hallucinations, mania
Dopamine blocking: breast changes, sexual dysfunction, (rarely extrapyramidal dyskinesia and tremor)
What drug should you not use with tricyclics?
Monoamine oxidase inhibitors - both increase serotonin and noradrenaline leading to serotonin syndrome, hyperthermia or hypertension
Beta 2 agonists adverse effects
tachycardia, palpitations, anxiety, tremor
Raised glucose
LABA can cause muscle cramps
Caution if has CVD as tachycardia can lead to arrhythmias or angina
What effects does Beta 2 agonists have on electrolytes?
Shifts potassium into cells - can treat hyperkalaemia
What must LABAs be used in conjunction with?
Inhaled corticosteroids
What drug may reduce effectiveness of Beta 2 agonists
Beta blockers
Why should verapamil not be given with a beta blocker? except under specialist supervision?
both can cause bradycardia or heart failure
What type of mask should be used in COPD and why?
Venturi
Avoids risk of T2RF (loss of hypoxic drive)
ABG criteria for long-term oxygen therapy and when should the criteria be assessed?
pO2 <7.3kpa
<8kpa in presence of complications - peripheral oedema, pulmonary hypertension, secondary polycythaemia, nocturnal hypoxaemia
> 8kpa if interstitial lung disease with severe dyspnoea
assess criteria twice, 3 weeks apart (and at least 4 weeks after an exacerbation)
Why is LMWH preferred over UH?
Lower risk of heparin-induced thrombocytopaenia (which can lead to clot growth)
No need for monitoring anti-factor Xa (unless high risk of bleeding, renal impairment or extremes of body weight)
Longer action, only needed once daily (twice in children)
Direct thrombin inhibitors
Dabigatran
Direct factor Xa inhibitors
Rivaroxaban
Apixaban
What type of drug is warfarin, and what are its indications?
Vitamin K antagonist
Treatment and prevention of VTE
Heart valve prostheses
AF
Target INR on anti-coagulation
2.5 (sometimes 3 or 3.5 depending on condition)
Warfarin absolute contraindications
Oesophageal varcies
Within 72 hours of surgery
Hypersensitivity
Pregnancy (and within 48 hours of delivery)
When should you use both warfarin and antiplatelet?
Prosthetic valve
Warfarin relative contraindications
Thrombocytopaenia Coagulation disorder GI bleed Uncooperative or unreliable patient Risk of falls or trauma Concomitant drugs that increase GI bleeding risk (antiplatelets, SSRI, NSAIDs, duloxetine, venlafaxine) Protein C deficiency Alcohol or drug abuse Renal impairment
What must a patient understand before commencing warfarin therapy?
Indication How long it will continue Potential hazards and benefits Need for regular monitoring Effect of concomitant drugs and illnesses Long-term and short-term management Potential requirement to vary dose
What leads to a hypercoaguable state in the early stages of warfarin therapy, and what is used to manage that?
Initial depletion of protein C (natural anti-coagulant)
Fast acting LMWH can be given
How to reverse effects of warfarin?
Small dose of Vitamin K - phytomenadione (IV or IM)
Large doses can induce warfarin resistance for up to a week
How is rapid loading of warfarin given?
Treatment takes 5-10 days to reach maximum effect, and is preceded by hypercoaguable state
Fast-acting LMWH given at the start until two consecutive days of target INR reached (around 4-5 days after starting)
How long does slow loading of warfarin take to reach maximum effect?
3-4 weeks
What should be monitored with patients on LMWH?
After 5 days, platelet count and potassium should be monitored (risk of HIT and hyperkalaemia)
Who are most at risk of hyperkalaemia when starting on LMWH?
Diabetics, CKD, potassium-sparing diuretics, acidosis
What baseline tests should be done before starting on LMWH?
INR, APTT, platelets LFTs
Coagulation disorder screening if INR>1.4 before therapy
How is LMWH dose calculated?
According to weight and clinical scenario (may change if obese or renal impairment)
Who should unfractionated heparin be used in?
Pregnancy or renal impairment (more easily reversible)
DVT or PE if LMWH has less evidence - UH is faster acting
What is the initial bolus for UH?
5000 units IV (or 75 units/kg)
Followed by 18 units/kg/hour
Slow loading starting dose for warfarin?
1 to 3mg
What factors should be considered before starting a patient on warfarin?
Drug history Allergies Liver function Renal function Thyroid function
How long should you be on warfarin for following PE or DVT?
At least 3 months
When should INR be checked following a warfarin dosage change?
2 days later
Management of major bleeding in a patient on warfarin?
When should you restart warfarin?
Stop warfarin
Give slow IV 5mg phytomenadione (can take over 6 hours for full reversal of warfarin): 1-3mg if minor bleed
Dried prothrombin complex - II, VII, XI, X (or fresh frozen plasma)
Restart warfarin when INR <5
In what patients should you give oral menadiol sodium instead of phytomenadione?
What dose tablets do they come in?
Patients with malabsorption syndromes (it is water soluble and so better absorbed)
10mg (can be halved)
Can take over 24 hours to reverse warfarin
What dosage tablets are usually used for warfarin?
1mg and 3mg (5mg can be used but uncommonly)
What drugs enhance the anti-coagulant effect of warfarin (those requiring a reduced dose)?
Amiodarone Macrolides, metronidazole, quinolones SSRIs, venlafaxine, mirtazapine Antifungals PPIs Statins Levothyroxine
What key points should be covered when counselling a patient about to start on warfarin?
Indication How long for Medications (colours and strengths) Dosage (loading and maintenance) Monitoring (INR and why it is important) Adherence (what to do if missed a dose) Drug interactions (alcohol under 2 units a day, avoid cranberry juice and eat consistent vitamin K foods) Side effects (signs of bleeding, when to seek medical attention) Obtaining medications Alerting other HCPs
Fast-acting insulins, and when to take them?
Insulin aspart (Novorapid) Insulin lispro (Humalog)
Taken just before eating
Short-acting insulins, and when to take them?
Porcine neutral
Actrapid
Humulin S
Insuman rapid
15-30 mins before meal
Long-acting insulin example
Insulin detemir (Levemir) Insulin glargine
Post-prandial blood glucose targets for T1 and T2 diabetes
T1: 5-9mmol/l
T2: <8.5 mmol/l
Intermediate acting insulin example?
Isophane (NPH) insulin
What is a twice-daily insulin regimen?
Biphasic isophane mixed insulins taken before breakfast and dinner
Require snacks between meals to counteract overlapping of the two and avoid hypoglycaemia
