PSA Passmed Stuff Flashcards
Malignancy causing SIADH
Small cell lung cancer
(also: pancreas +prostate)
4 Neurological causes of SIADH
Stroke
SAH
SDH
Meningitis/ encephalitis/ abscess
2 Infectious causes of SIADH
TB
Pneumonia
6 Drug causes of SIADH
Sulfonylureas
SSRIs
TCAs
Carbamezapine
Vincristine
Cyclophosphamide
Which sulfonylureas cause SIADH?
Glimepiride
Glipizide
2 other causes of SIADH
Positive end-expiratory pressure (PEEP)
Porphyrias
What are the investigations for SIADH?
Urine osmolality: HIGH
Serum osmolality: LOW
(inappropriate as kidneys should dilute urine when serum osmolality is low)
Urine sodium: HIGH (due to action of ADH on renal tubules)
Describe management of SIADH
Correct slowly to avoid precipitating central pontine myelinolysis
Fluid restriction
Demeclocycline: reduces responsiveness of the collecting tubule cells to ADH
In which patients requiring fluid should glucose be avoided?
Stroke patients (non-hypoglycaemic)
Due to increased risk cerebral oedema
Prescribe normal saline if rehydration required
What are the maintenance fluid requirements?
25-30 ml/kg/day of water
+
~1 mmol/kg/day of potassium, sodium + chloride
+
~50-100 g/day of glucose to limit starvation ketosis
Describe maintenance fluid requirements for an 80kg patient
2L water
80 mmol potassium
Describe the electrolyte contents of 0.9% saline
Na+: 154 mmol
Cl-: 154 mmol
What does 5% glucose contain?
50g glucose
Describe the contents of Hartmann’s solution
Na+: 131
Cl-: 111
K+: 5
HCO3-: 29
What is the risk of using large volumes 0.9% saline?
Hyperchloraemic metabolic acidosis
In which patients should Hartmann’s not be used? Why?
Hyperkalaemic patients
Hartmann’s contains potassium
List 6 drugs that can cause impaired glucose tolerance
Diuretics
Steroids
Immunosuppressants
Interferon-alpha
Nicotinic acid
Antipsychotics
Which diuretics are cause impaired glucose tolerance?
Thiazides
Furosemide (less common)
Which drug can cause slight impairment of glucose tolerance?
B-blockers
Also use with caution in diabetics as can interfere with metabolic + autonomic responses to hypoglycaemia
Name 2 Immunosuppressants that cause impaired glucose tolerance
Tacrolimus
Ciclosporin
List 5 drugs that may cause urinary retention
TCAs e.g. amitriptyline
Anticholinergics e.g. antipsychotics, antihistamines
Opioids
NSAIDs
Disopyramide
List 5 drugs that can cause lung fibrosis
Amiodarone
Cytotoxic agents: busulphan, bleomycin
Anti-rheumatoid drugs: methotrexate, sulfasalazine
Nitrofurantoin
Ergot-derived dopamine receptor agonists (bromocriptine, cabergoline)
List 3 significant adverse effects which patients should be warned about when starting Allopurinol
Severe cutaneous adverse reaction (SCAR)
Drug reaction with eosinophilia + systemic symptoms (DRESS)
Stevens-Johnson syndrome
List 3 ethnic groups at higher risk of dermatological reactions of Allopurinol
Chinese
Korean
Thai
Name 3 drugs that interact with Allopurinol
Azathioprine
Cyclophosphamide
Theophylline
Describe the interaction between Allopurinol and Azathioprine
Xanthine oxidase is responsible for metabolism of 6-mercaptopurine (metabolite of Azathioprine)
Thus, Allopurinol leads to high levels of 6-mercaptopurine
A much reduced dose (e.g. 25%) must therefore be used if the combination can’t be avoided
Describe the interaction between Allopurinol and Cyclophosphamide
Allopurinol reduces renal clearance, therefore may cause marrow toxicity
Describe the interaction between Allopurinol and Theophylline
Allopurinol causes an increase in plasma conc. of theophylline by inhibiting its breakdown
Aspirin potentiates which 3 drugs/ classes
Oral hypoglycaemics
Warfarin
Steroids
Why should Aspirin be avoided in children? What is the exception to this?
Risk of Reye’s syndrome
Kawasaki: benefits outweigh risk
Name 2 non-dihydropyridine CCBs
Verapamil: highly negatively inotropic
Diltiazem: less negatively inotropic
Name 2 dihydropyridine CCBs
Amlodipine
Nifedipine
Felodipine
What are the indications of Verapamil?
Angina
HTN
Arrhythmias
Name 3 contraindications to verapamil
Heart failure
Bradycardia
Hypotension
List 2 side effects of Verapamil
Flushing
Constipation
What drug should not be given with Verapamil? Why?
DONT give with b-blockers
May cause heart block
Name 2 indications for Diltiazem
Angina
HTN
List 3 contraindications to Diltiazem
Hypotension
Bradycardia
Heart failure
Name 2 side effects of Diltiazem
Constipation
GI discomfort
List 3 indications for dihydropyridine CCBs
HTN
Angina
Raynauds
Which CCBs do not result in worsening of heart failure?
Dihydropyridine CCBs
Affect peripheral vascular smooth muscle more than myocardium
List 3 side effects of dihydropyridines
Flushing
Headache
Ankle swelling
What effect may be seen with shorter acting dihydropyridines? Give an example drug
Nifedipine
Cause peripheral vasodilation which may result in reflex tachycardia
List 5 indications for Ciclosporin
Following organ transplantation
RhA
Psoriasis (direct effect on keratinocytes as well as modulating T cell function)
UC
Pure red cell aplasia
What is Ciclosporin?
Immunosuppressant
Calcineurin inhibitor
What organs can be adversely affected with Ciclosporin use?
Nephrotoxicity
Hepatotoxicity
List 3 adverse abnormalities in the blood caused by cyclosporin
Hyperkalaemia
Impaired glucose tolerance
Hyperlipidaemia
List 6 adverse clinical features of Ciclosporin use
Fluid retention
HTN
Hypertrichosis (excess hair)
Gingival hyperplasia
Tremor
Increased susceptibility to severe infection
What drug can increase the concentration of ciclosporin?
Cannabidoil
What is Digoxin?
Cardiac glycoside
Mainly used for rate control in AF Mx
What properties allow use of Digoxin in heart failure? What is the effect of this?
Positive inotropic properties
Improves Sx but not mortality
What is the MOA of digoxin?
Decreases conduction through the AV node which slows the ventricular rate in AF + flutter
increases force of cardiac muscle contraction due to inhibition of the Na+/K+ ATPase pump.
Also stimulates vagus nerve
If Digoxin toxicity is suspected when should plasma concentration be measured?
Within 8-12h of last dose
List 6 symptoms of Digoxin toxicity
Malaise
Lethargy
N+V
Anorexia
Confusion
Yellow-green vision
Give 2 clinical signs of Digoxin toxicity
Arrhythmias (e.g. AV block, bradycardia)
Gynaecomastia
What is the classic precipitant to Digoxin toxicity?
Hypokalaemia
Digoxin normally binds to the ATPase pump on the same site as K+ Hypokalaemia → digoxin more easily bind to the ATPase pump → increased inhibitory effects
List 7 drugs associated with Digoxin toxicity
Amiodarone
Quinidine
Verapamil
Diltiazem
Spironolactone
Ciclosporin
Drugs that cause hypokalaemia e.g. Thiazides + loop diuretics
Describe management of Digoxin toxicity
Digibind: Digoxin-specific antibody Fab fragments
Correct arrhythmias
Monitor potassium
What is the class of Gentamicin? Describe its pharmacokinetics
Aminoglycoside
Poorly lipid soluble, thus given parentally or topically
Name 2 adverse effects of gentamicin
Ototoxicity
Nephrotoxicity
Give a contraindication to Gentamicin
Myasthenia Gravis
Describe dosing of Gentamicin
Peak (1h after admin) + trough levels (just before next dose) are measured
High peak: decrease dose
High trough: increase interval between doses
