Prescription review: a foolproof plan Flashcards
Key points: question 1
- Haemoptysis (blood in sputum), so stop aspirin (an antiplatelet) and prophylactic enoxaparin (a low molecular weight (LMW) heparin)
- Hyperkalaemic, so stop the ACE-inhibitor (ramipril) (may contribute to renal failure) and IV fluid containing potassium (and start an alternative).
- Penicillin allergy, so stop co-amoxiclav and start an alternative
- This patient is receiving 6 g/day of paracetamol (i.e. 2 g more than the maximum dose): the frequency should be
6-hourly not 4-hourly.
PReSCRIBER mnemonic to avoid common pitfalls
● Patient details
● Reaction (i.e. allergy plus the reaction)
● Sign the front of the chart
● check for Contraindications to each drug
● check Route for each drug
● prescribe Intravenous fluids if needed
● prescribe Blood clot prophylaxis if needed
● prescribe antiEmetic if needed and
● prescribe pain Relief if needed.
What must you add to a new chart
3 pieces of PID
What do co-amoxiclav and Tazocin both have
Penicillin
Important groups of drugs to be aware of contraindications (4)
- Drugs that increase bleeding
- Steroids
- NSAIDs
- Antigypertensives
- Drugs that increase bleeding
Drugs that increase bleeding (aspirin, heparin and warfarin) should not be given to patients who are bleeding, suspected of bleeding, or at risk of bleeding (e.g. those with a prolonged prothrombin time due to liver disease).
Do not forget that prophylactic heparin is contraindicated in acute ischaemic stroke due to the risk of bleeding into the stroke.
If presents with excessive coagulation, check for enzyme inhibitors e.g. erythromycin –> can increase warfarin’s effect (and thus the prothrombin time (PT) and international normalized ratio (INR)) despite a stable dose.
- Steroids
Remember side effects (/contraindications) as STEROIDS:
Stomach ulcers
Thin skin
Edema
Right and left heart failure
Osteoporosis
Infection (inc candida)
Diabetes (commonly causes hyperglycaemia and uncommonly progresses to diabetes)
cushing’s Syndrome
- NSAIDS
NSAID:
No urine (i.e. renal failure)
Systolic dysfunction (i.e. heart failure)
Asthma
Indigestion (any cause)
Dyscrasia (clotting abnormality).
While aspirin is technically a NSAID, it is not contraindicated in renal or heart failure, or in asthma.
- Antihypertensives
Think of the side effects in three categories:
a. Hypotension (including postural hypotension) that may
result from all groups of antihypertensives.
b. Dividing the groups of antihypertensives into two
mechanistic categories:
1. BB and CCB –> Bradycardia
2. ACEi and diuretics –> Electrolyte disturbance
c. Individual drug classes have specific side effects:
1. ACE-inhibitors –> dry cough.
2. Beta-blockers –> wheeze in asthmatics; worsening of acute heart failure (but helps chronic heart failure).
3. Calcium-channel blockers –> peripheral oedema and flushing.
4. Diuretics –> renal failure.
Loop diuretics (e.g. furosemide) can also cause gout
Potassium-sparing diuretics (e.g. spironolactone) can cause gynaecomastia
Route
If patient vomiting –> IV/IM/SC
Doses for common antiemetics are usually the same regardless or route e.g. metoclopramide 10mg 8-hrly and cyclizine 50mg 8hrly
PATIENTS WHO ARE NBM STILL NEED THEIR ORAL MEDICATION
Intravenous fluids: when do you prescribe them (2 situations)
- Replacement
- Maintenance
Replacement fluids: what to prescribe usually
Always 0.9% NaCl (crystalloid), unless:
Replacement fluids: if hypernatraemic or hypoglycaemic
5% dextrose
Replacement fluids: ascites
Human Albumin Solution - maintains oncotic pressure + higher sodium concentration would worsen ascites
Replacement fluids: shocked with BP <90mmHg
Gelofusine (colloid) - high osmotic content, so stays intravascular for longer, maintaining BP
Replacement fluids: shocked from bleeding
blood transfusion, colloid if no blood available
Replacement: how much fluid and how fast? - what to assess first
Start by assessing
the HR, BP and urine output
Replacement: how much fluid and how fast? - if tachycardic or hypotensive
500 mL bolus immediately
(250 mL if HF) then reassess patient, especially HR, BP and urine output to assess response and speed of next bag of IV fluid.
Replacement: how much fluid and how fast? - If only oliguric (and not due to urinary obstruction (e.g. an
enlarged prostate))
1 L over 2–4 h then reassess
patient, especially and HR, BP and urine output to assess
response and speed of next bag of IV fluid.
Predicting how fluid depleted adult patient is by looking at obs
▸ reduced urine output (oliguric if <30 mL/h; anuric if 0 mL/h)
indicates 500 mL of fluid depletion
▸ reduced urine output plus tachycardia indicates 1 L of fluid
depletion
▸ reduced urine output plus tachycardia plus shocked
indicates >2 L of fluid depletion.
Don’t usually give >2L at once
What does 2º mean on a drug chart?
2 hourly
What is the fastest IV potassium can be prescribed
IV potassium should not be given at more than 10 mmol/hour
Daily maintenance fluid requirements
1. Water
2. Potassium, sodium and chloride
3. Glucose
- 25-30 ml/kg/day of water and
- 1 mmol/kg/day of potassium, sodium and chloride
- 50-100 g/day of glucose to limit starvation ketosis (however note this will not address the patient’s nutritional needs)
What would an appropriate regimen be for daily fluid maintenance?
The traditional regime = “1 salty + 2 sweet”:
1. Saline 0.9% + 20mmol potassium chloride (over 8 hours)
2. Dextrose 5% + 20mmol potassium chloride (over 8 hours)
3. Dextrose 5% + 20mmol potassium chloride (over 8 hours)
Assessing fluid status IRL
- Check the patient’s U&E to confirm what to give them.
- Fluid overloaded (e.g. increased jugular venous
pressure (JVP), peripheral and pulmonary oedema). - Ensure bladder is not palpable (signifying urinary obstruction) if giving replacement fluids because of ‘reduced urine output’.
Special situations for maintenance fluids
- Post-op
- Sepsis
- Liver failure
- Acute renal failure
- Chronic renal failure
- History of alcohol excess/poor nutrition
- Brain hemorrhage
- Re-feeding syndrome
- Post-op: K+ may increase due to cell lysis
- Sepsis: intravascular fluid depletion –> use Hartmann’s and avoid high Na+ and Cl-
- Liver failure: Excess Na+ may cause ascites so ONLY use 5% dextrose
- Acute renal failure: avoid potassium supplementation
- Chronic renal failure: avoid excess fluids, sodium and potassium (the kidneys can’t excrete these effectively)
- History of alcohol excess / poor nutrition
Give Pabrinex before giving any 5% dextrose (even if hypoglycaemic) or the glucose load can precipitate Korsakoff’s syndrome - Brain haemorrhage
Avoid dextrose (can worsen oedema due to osmotic shifts)
Saline would be a good first choice
-Risk of re-feeding syndrome
Avoid dextrose where possible because it can precipitate re-feeding syndrome
Special situations for maintenance fluids
- Post-op
- Sepsis
- Liver failure
- Acute renal failure
- Chronic renal failure
- History of alcohol excess/poor nutrition
- Brain hemorrhage
- Re-feeding syndrome
- Post-op: K+ may increase due to cell lysis
- Sepsis: intravascular fluid depletion –> use Hartmann’s and avoid high Na+ and Cl-
- Liver failure: Excess Na+ may cause ascites so ONLY use 5% dextrose
- Acute renal failure: avoid potassium supplementation
- Chronic renal failure: avoid excess fluids, sodium and potassium (the kidneys can’t excrete these effectively)
- History of alcohol excess / poor nutrition
Give Pabrinex before giving any 5% dextrose (even if hypoglycaemic) or the glucose load can precipitate Korsakoff’s syndrome - Brain haemorrhage
Avoid dextrose (can worsen oedema due to osmotic shifts)
Saline would be a good first choice
-Risk of re-feeding syndrome
Avoid dextrose where possible because it can precipitate re-feeding syndrome
Types of fluids
Sodium chloride 0.9% (Normal saline)
Hartmann’s
Sodium chloride 0.18% / Glucose 4%
5% Dextrose
Gelofusine
VTE prophylaxis
1. If patient bleeding
2. If peripheral arterial disease
LMW heparin (e.g. dalteparin 5000 units daily s/c) + compression stockings for prevention of
venous thromboembolism.
- Do not prescribe VTE prophylaxis
- Should not be prescribed stockings
Antiemetics traps
Avoid metoclopramide for:
- Parkinson’s (exacerbates)
- Young women (dyskinesia)
Antiemetic choices (see BNF for dosages)
1. nauseated
2. not nauseated
- cyclizine (careful as causes fluid retention)
- if heart failure - metoclopramide
- alternative: ondansetron
2.PRN
- cyclizine (can cause fluid retention)
- metoclopramide if HF
Note: can use cyclizine as 1st line in many cases, except cardiac cases (metoclopramide is safer)
Pain relief:
1. neuropathic pain
2. painful diabetic neuropathy
- Amitriptyline or pregabalin
- Duloxetine
Pain relief
Analgesic choices
No pain PRN Paracetamol 1 g up to 6 hourly oral (max 4g)
Mild pain:
- Regular paracetamol 1 g 6 hourly oral
PRN Codeine 30 mg up to 6 hourly oral
Severe pain
- Regular: Co-codamol 30/500, 2 tablets 6 hourly oral
- PRN Morphine sulphate (10 mg/5 mL) 10 mg up to 6 hourly oral∗∗
DON’T WRITE ORAMORPH, write morphine sulphate
Common trap: paracetamol
may be taking paracetamol + co-codamol, exceeding the 4g a day max dose of paracetamol (check)
Paracetamol max dose if <50kg
500mg QDS (max dose 2g)
Question 2.2 Key points
Neo-Naclex = bendroflumethiazide
= increased potassium excretion
Metoclopramide and domperidone are both dopamine antagonists. Metoclopramide crosses the blood-brain barrier, but domperidone does not–> safe in Parkinson’s
Q2.3
COUGH - lisinopril
Hyperkalaemia - lisinopril
Ace-i cause HYPERkalaemia
Bendroflumethiazide and loop diuretics cause HYPOkalaemia
Q2.4
Indigestion - NSAIDs + steroid (inhibit renewal of gastric epithelial renewal)
Renal failure - NSAIDs (reduce renal artery diameter) + ACE-i (angiotensin II preserves glomerular filtration in reduced blood flow)
Q2.5
Dry eyes + poor accomodation - antimuscarinic (oxybutinin)
Drugs to review in elderly confusion - tramadol + cyclizine (causes drowsiness due to anticholinergic effects) + diazepam
Q2.5
Dry eyes + poor accomodation - antimuscarinic (oxybutinin)
Drugs to review in elderly confusion - tramadol + cyclizine (causes drowsiness due to anticholinergic effects) + diazepam
Q2.6
- Methotrexate + NSAID = increased risk of nephrotoxicity
- NSAID in asthma - bronchoconstriction
- Paracetamol trap
- Trimethoprim ALSO folate antagonist (like methotrexate) –> bone marrow toxicity, pancytopenia, neutropenic sepsis
Methotrexate must be held in active infection
Q2.7
- Loop diuretics and thiazide diuretics cause hypokalaemia (ACE-i and K+ sparing diuretics cause HYPERkalaemia)
- Stop furosemide + amlodipine (s/e: peripheral oedema) + heparin
- Don’t use heparin in ischaemic stroke (DOAC)
Q2.8
- high INR - stop enoxaparin and warfarin
- stop verapamil (CCB = peripheral oedema)
- stop furosemide - culprit is CCB, furosemide may lead to electrolyte disturbance
CCB + b blocker can cause hypotension and bradycardia
Q2.9
- stop b blocker + NSAID (double bronchoconstriction)
- stop aspirin (2g is waay too high)
- stop co-amoxiclav (allergic to penicillin)
Q2.10
- stop COCP (migraine with aura)
- stop enoxaparin (post stroke)
- stop bisoprolol (200mg is too high, usually 10mg)
- Novomix alway S/C, unless sliding scale
- sliding scale with SAI, Novomix has MAI and SAI
