Pharmacology Flashcards
What are the properties of the main three DOACs?
- Mechanism
- Excretion
- Indications
Apixaban
- Factor Xa inhibitor
- Faecal excretion
Rivaroxaban
- Factor Xa inhibitor
- Liver excretion
Dabigatran
- Thrombin inhibitor
- Renal excretion
All are indicated for:
- Prevention of VTE following hip/knee surgery
- Treatment of DVT and PE
- Prevention of stroke in non-valvular AF*
All are taken orally
What info do you need to include on a PRN medication ?
Indication and maximum frequency (max dose or BD etc.)
Mnemonic for enzyme (p450) inducers?
PC BRAS
Phenytoin
Carbamazepine
Barbiturates
Rifampicin
Alcohol (chronic)
Sulphonylureas
Mnemonic for enzyme inhibitors?
AO DEVICES
Allopurinol
Omeprazole
Disulfiram Erythromycin Valproate Isoniazid Ciprofloxacin Ethanol Sulphonamides
What should you do with prescribing long-term drugs if patient is having surgery?
Some need to be stopped (I LACK OP)
Most should be continued
Steroids need to be increased (and given IV)
What drugs need to be stopped before surgery?
I LACK OP
Insulin
Lithium - day before
Anticoag/platelets
COCP/HRT - 4 weeks before
K+ sparing diuretics - Day of
Oral hypoglycaemics
Perindopril (and other ACEI) - Day of
Mnemonic to use when looking for prescription errors?
PReSCRIBER
Patient details Reaction Sign the front of the chart Contraindications for each drug check Route of each drug check IV fluid if needed Blood clot prohylaxis if needed ant-Emetic if needed Relief from pain - prescribe if necessary
4 main groups of drugs that can be contraindicated?
- Drugs that increase bleeding risk should not be given to a bleeding patient, a suspected bleeding patient, or one at risk.
- Steroids (if showing S/Es) (STEROIDS)
- Stomach ulcers
- Thin skin
- Edema
- Right and left HF
- Osteoporosis
- Infection
- Diabetes
- Syndrome of Cushings
3. NSAIDS for NSAIDS No urine - Systolic dysfunction (HF) Asthma Indigestion Dyscrasia (clotting disorder)
- (Aspirin only in Indigestion and clotting).
4. Antihypertensives have three categories
1. Hypotension
- Mechanisms
a. Electrolyte disturbance with ACEI
b. Bradycardia with B-blockers - Specific S/Es
- ACEI - dry cough
- BBlockers - wheeze in asthmatics
- Calcium channel blockers - peripheral oedema and flushing
- Diuretics - renal failure
When is erythromycin most commonly contraindicated?
Concomitant prescription with warfarin (Enzyme inhibitor)
When is prophylactic heparin commonly contraindicated?
Acute ischaemic stroke
Steroid S/Es mnemonic?
(STEROIDS)
- Stomach ulcers
- Thin skin
- Edema
- Right and left HF
- Osteoporosis
- Infection
- Diabetes
- Syndrome of Cushings
NSAIDS contraindication mnemonic?
NSAID
No urine - Systolic dysfunction (HF) Asthma Indigestion Disordered clotting
In what two situations do you prescribe fluids?
Replacement fluids
Maintenance fluids
Which fluids should you use in replacement?
- 9% saline in ALL unless:
- Pt is hypernatraemic or hypoglycaemic: 5% dextrose
- Has Ascites: Human-Albumin Solution (HAS)
- Is shocked, with systolic BP <90mmHg: give gelofusin (apparently)
- Is shocked after bleeding (give blood).
How much fluid should you give when giving as replacement?
If tachycardic/hypotensive then give 500ml bolus (250 in HF)
If only oliguric then give 1L over 2-4 hours then reassess (HR, BP and urine O/P) then change according to their response.
As a general rule don’t prescribe >2L of fluid for a sick patient
What fluids should you give and how much (vol) should you give in maintenance therapy?
General rule: Adults 3L over 24 hours, Elderly 2L.
1 salty 2 sweet: 1L 0.9% saline followed by 2L 5% Dextrose.
Potassium should be guided by U&Es. If normal then:
- 40mmol KCL (20mmol in two bags).
- NO MORE THAN 10mmol AN HOUR)
How fast should you give maintenance fluids?
3L a day = 8hrly bags (24hrs/3)
2L a day = 12 Hrly bags (24hrs/3)
In RL must:
- Check U&Es
- Check fluid status (JVP, oedema)
- Check pts bladder is not palpable (obstruction)
When are compression stockings contraindicated?
Patient with peripheral arterial disease (PAD)
What antiemetic should you prescribe, and when?
Cyclizine in most cases (50mg) any route, apart from heart failure (worsens fluid retention)
In Heart Failure metoclopramide 10mg, however is dopamine antagonist so not in:
- Parkinson’s disease
- Young women (dyskinesia)
Pain control prescribing guidance/rules?
No pain
- PRN Paracetamol 1g up to 6hrly, oral
Mild Pain
- Paracetamol 1g 6hrly, oral
- PRN Codeine 30mg, up to 6-hrly oral
Severe pain
- co-codamol 30/500 2 tablets 6 hrly oral
- PRN morphine sulphate 10mg up to 6-hrly oral
Can introduce ibuprofen (400mg 8-hrly) if not contraindicated
Neuropathic pain is different (amitriptyline or pregabalin)
Electrolyte disturbance caused by thiazide diuretics (e.g. bendroflumethiazide)
Hypokalaemia
What main class of medications should be stopped in constipation?
Opiates - constipation.
What diuretics might cause both hypokalaemia and hyponatraemia?
All diuretics can cause hyponatraemia
Loop and thiazide diuretics can also cause hypokalaemia
Pt is on Furosemide, paracetamol, aspirin, enalapril, amlodipine and enoxaparin, pt has peripheral oedema (not caused by HF) what is the most likely culprit?
Amlodipine - Peripheral oedema is S/E of Ca++ channel blockers
What two commonly prescribed drug classes can exacerbate asthma?
NSAIDS, B-Blockers
What calcium channel antagonist can’t be used with beta blockers?
Verapamil
What route do you give insulin? When is this not so?
Given Subcut, apart from in sliding scales where is is IV - rapid acting
If a patient has asthma (but is asymptomatic) and is on ibuprofen, does it need to be stopped?
No it doesn’t - probably not NSAID-sensitive.
However with symptoms i.e. wheeze, then should be stopped.
General causes of anaemia as per their MCV?
Microcytic
- Iron deficiency anaemia
Normocytic anaemia
- Anaemia of chronic disease
- Acute blood loss
Macrocytic anaemia
- B12/Folate deficiency
- Excess alcohol intake/Liver disease
How to remember causes of hypernatraemia?
Begins with d Hyper-big d?
Dehydration
Drips (too much IV saline)
Drugs (with high sodium content)
Diabetes insipidus
Common causes of high neutrophils, low neutrophils and high lymphocytes (separately)?
High neutrophils
- Bacterial infection
- (tissue damage/steroids)
Low Neutrophils
- Viral infection
- Clozapine
- Carbimazole
High lymphocytes
- Viral infection
- (Lymphoma/CLL)
Common causes of low platelets (thrombocytopenia)
Reduced production
- Viral infection
- DRUGS (penicillamine)
Increased destruction
- Heparin
- Hypersplenism
- (DIC/ITP)
Common causes of high platelets (thrombocytosis)?
Reactive:
- Tissue damage (Infection/inflammation)
- Bleeding
Primary
- Myeloproliferative disorders
How do you remember the causes of SIADH?
SIADH
- Small cell lung cancer
- Infection
- Abscess
- Drugs (carbamazepine)
- Head injury
Causes of hyponatraemia? (just the important/common ones)
Hypovolaemia
- Fluid loss (vomiting/diarrhoea)
- Diuretics
Euvolaemic
- SIADH
Hypervolaemia
- Heart, Renal and Liver failure
How do you remember causes of hypokalaemia?
DIRE
Drugs (loop and thiazide diuretics)
Inadequate intake/Intestinal losses
Renal tubular acidosis
Endocrine
How do you remember causes of hyperkalaemia?
DREAD
Drugs (K+ sparing diuretics and ACEI) Renal failure Endocrine (addisons) Artefact due to clotted sample DKA
What are the three different types (causes) of AKI, their respective biochemical disturbance and their causes?
Prerenal (70%)
- Urea will be higher than creatinine
- Dehydration
- Shock
- Renal artery stenosis
Intrarenal (intrinsic) (10%)
- Creatinine rise much higher than urea
- Most importantly: Nephrotixic abx, DAMN drugs
Postrenal
- Urea rise is smaller than creatinine rise
- Something in the Urinary tract, stone, tumour, fibrosis, BPH/prostatic cancer.
How do you remember the other causes of an ALP rise?
ALKPHOS
Any fracture Liver damage K for kancer Pagets disease of bone Hyperparathyroidism Osteomalacia Surgery
What is the trick to changing the dose of Levothyroxine following TFTs?
Use TSH as a guide - aim for 0.5-5
If <0.5 then need to decrease (Hi TSH - too much thyroid, need to reduce)
If above then need to increase (Still hypothyroid).
Change by smallest amount offered
LFT results in prehepatic jaundice?
Isolated raise in Bilirubin (Haemolysis, Gilberts)
LFT results in intrahepatic jaundice?
Bilirubin rise in addition to ALP/ALT
LFT results in post-hepatic jaundice?
Raised bilirubin and ALP (Not ALT/AST).
ABG interpretation routine (PSA)?
- Check FiO2 (%)
- If on O2 and not sure about PaO2, subtract 10 from FiO2 and if PaO2 is lower then the pt is hypoxic. - Check PaO2 and PaCO2
- T1RF (Low pO2 and low/normal CO2) - Heart/Lung damage
- T2RF (Low pO2 and high CO2) - COPD, neuromuscular failure, chest wall deformity - Acid/base
- Look at pH, then PCO2 and HCO3
- Only CO2 abnormal = resp cause
- Only HCO3 abnormal = metabolic cause
- If both high or both low then there is compensation (if pH is not normal only partially compensated)
- if they are both abnormal but in opposite directions then there is both metabolic disorder and respiratory disorder, - Think about cause
Resp alkalosis - rapid breathing
Resp acidosis - COPD, neuromuscular failure, chest wall deformity
Metabolic alkalosis - Vomiting, diuretics, conns syndrome
Metabolic acidosis - DKA, Renal failure, ethanol/methanol
What are the DAMNN drugs that can cause AKI?
Diuretics ACEI Metformin Nitrofurantoin/trimethoprim NSAIDS
What are the cholinergic S/Es?
SLUD
Salivation
Lacrimation
Urination
Diarrhoea
(also midriasis, fasciculation, Hypotension and bradycardia)
Apart from the William Marrow technique what else will you see in Bundle branch block?
Wide QRS = >3 small squares, if they are wide check for BBB
Most common drugs that require monitoring?
Digoxin Theophylline Lithium Phenytoin Abx - Gent, vancomycin Warfarin (obvs)
If the serum drug level is high, but the patient has serum level what should you do?
Still decrease the drug dose, apart from gent
If there are signs of toxicity, omit the drug for several days
What symptoms do you get in Digoxin Toxicity?
Confusion, Nausea, Visual halos, arrhythmias
What symptoms do you get in lithium toxicity?
Early: tremor
Mid: Lethargy
Late: arrhythmias, seizures, coma, renal failure
Phenytoin toxicity symptoms?
Gum hypertrophy, ataxia, nystagmus, peripheral neuropathy and teratogenicity.