Prescribing Flashcards
Drugs to stop before surgery
I LACK OP
Insulin
Lithium
Anticoagulants
COCP/HRT
K-sparing diuretics
Oral hypoglycaemics
Perindopril and other ACE-inhibitors
I LACK OP
Insulin
Lithium - Day before
Anticoagulants
COCP/HRT - 4 weeks before
K-sparing diuretics - Day of
Oral hypoglycaemics
Perindopril and other ACE-inhibitors - Day of
Drugs to stop before surgery
Surgery for patients on long term corticosteroids
Commonly have adrenal atrophy so unable to mount an adequate physiological response to surgery => profound hypotension if steroids discontinued
Should be given IV steroids at induction of anaesthesia
What does an enzyme inducer do?
Increases P450 enzyme activity, hastening metabolism of other drugs and reducing their effect => patient requires more of some other drugs in the presence of an enzyme inducer
Increased enzyme activity => decreased drug concentration
What does an enzyme inhibitor do?
Decreases P450 enzyme activity, increasing the levels of other drugs, requiring reduced dosage
Cytochrome P450 enzyme system
Metabolises most drugs to inactive metabolites in the liver, preventing them from exerting infinite effects.
Enzyme inducers (decreased drug level)
Decreased drug concentration
PC BRAS
Phenytoin
Carbamazepine
Barbiturates
Rifampicin
Alcohol (chronic excess)
Sulphonylureas
Enzyme inhibitors
Increase drug concentration
AODEVICES
Allopurinol
Omeprazole
Disulfiram
Erythromycin
Valproate
Isoniazid
Ciprofloxacin
Ethanol (acute intoxication)
Sulphonamides
What should be stopped with any bleeding?
Antiplatelets/anticoagulants
eg Enoxaparin, aspirin, dalteparin
When should you be cautious with warfarin?
With an enzyme inhibitor- can greatly increase INR
Steroid side effects
STEROIDS
Stomach ulcers
Thin skin
oEdema
Right and left heart failure
Osteoporosis
Infection
Diabetes (commonly causes hyperglycaemia, uncommonly progresses to diabetes)
cushing’s Syndrome
Safety considerations for NSAIDs
NSAID
No urine
Systolic dysfunction (ie HF)
Asthma
Indigestion
Dyscrasia (clotting abnormality)
Antihypertensive side effects
Hypotension
Bradycardia with beta blockers and some CCBs
Electrolyte disturbance with ACEi and diuretics
ACEi - dry cough
Beta blockers => wheeze in asthmatics, worsen acute HF but can help chronic
CCBs => peripheral oedema and flushing
Diuretics => renal failure, thiazide diuretics can cause gout, K sparing can cause gynaecomastia
Vomiting patient
GIVE MEDICINE NON ORAL ROUTE
Replacement fluid: which fluid for standard patient?
0.9 % saline
Replacement fluid: when not to give 0.9 % saline?
Hypernatraemia or hypoglycaemia => 5 % dextrose instead
Has ascites => give human albumin solution (HAS) instead
Shocked from bleeding => give blood transfusion but crystalloid first if blood not available
Replacement fluid: how fast if tachycardic or hypotensive?
500 ml bonus immediately (250 ml in Hx of HF)
Replacement fluid: how fast if only oliguric (not due to obstruction)?
1 L over 2-4 hours then reassess
Max infusion rate of IV potassium?
10 mmol/hour
Maintenance fluids: how much for adults/elderly in 24 hours?
Adults - 3 L
Elderly - 2 L
Maintenance fluid: which fluid should be prescribed?
1 L of 0.9 % saline, 2 L of 5 % dextrose
Add KCl guided by U&Es
For normal potassium level, approx 40 mmol required each day - 20 mmol in each bag
Maintenance fluids: how fast to give each bag?
If giving 3 L per day = 8 hourly bags
If giving 2 L per day = 12 hourly bags
When not to prescribe anticoagulants
When not to prescribe compression stockings
RISK OF BLEEDING
Recent ischaemic stroke
PERIPHERAL ARTERIAL DISEASE - may cause acute limb ischaemia
When to avoid metoclopramide?
Dopamine antagonist
Parkinson’s patients - may exacerbate symptoms
Young women due to risk of dyskinesia
Antiemetic in nauseated patients
Regular antiemetic
Cyclizine 50 mg 8-hourly IM/IV/oral for most cases but causes fluid retention
Metoclopramide 10 mg 8-hourly IM/IV if HF
Ondansetron 4 mg or 8 mg 8-hourly IV/oral
Antiemetic in not nauseated patients
As required antiemetic
Cyclizine 50 mg 8-hourly IM/IV/oral for most cases but causes fluid retention
Metoclopramide 10 mg up to 8-hourly IM/IV if HF
When not to use cyclizine?
Cardiac cases as it can worsen fluid retention
Causes of microcytic anaemia
Iron deficiency anaemia
Thalassaemia
Sideroblastic anaemia
Causes of normocytic anaemia (4)
Anaemia of chronic disease
Acute blood loss
Haemolytic anaemia
Chronic renal failure
Causes of macrocytic anaemia
B12/folate deficiency (megaloblastic anaemia)
Excess alcohol
Liver disease (including non alcoholic causes)
Hypothyroidism
Haematological diseases starting with “M”: myeloproliferative, myelodysplastic, multiple myeloma
Causes of high neutrophils
Bacterial infection
Tissue damage (inflammation/infarct/malignancy)
Steroids
Causes of low neutrophils
Viral infection
Chemotherapy or radiotherapy
Clozapine (antipsychotic)
Carbimazole (antithyroid)
Causes of high lymphocytes
Viral infection
Lymphoma
CLL
Causes of thrombocytopenia
REDUCED PRODUCTION
Infection
Drugs (penicillamine)
Myelodysplasia, myelofibrosis, myeloma
INCREASED DESTRUCTION
Heparin
Hypersplenism
DIC
ITP
HUS
TTP
Causes of thrombocytosis
REACTIVE
Bleeding
Tissue damage (infection/inflammation/malignancy)
Postsplenectomy
PRIMARY
Myeloproliferative disorders
Causes of hypovolaemic hyponatraemia
Fluid loss (diarrhoea/vomiting)
Addison’s
Diuretics (any type)
Causes of euvolaemic hyponatraemia
SIADH
Psychogenic polydipsia
Hypothyroidism
Causes of hypervolaemic hyponatraemia
Heart failure
Renal failure
Liver failure (causing hypoalbuminaemia)
Nutritional failure (causing hypoalbuminaemia)
Thyroid failure (can also be euvolaemic)
Causes of SIADH
SIADH
Small cell lung tumours
Infection
Abscess
Drugs (carbemazepine and antipsychotics)
Head injury
Causes of hypercalcaemia (5)
EXCESSIVE PTH PRODUCTION
Primary hyperparathyroidism (adenoma, hyperplasia)
Tertiary hyperparathyroidism (long-term stimulation of PTH secretion in renal insufficiency)
EXCESSIVE VITAMIN D PRODUCTION
Granulomatous diseases (sarcoidosis, TB)
Lymphomas
Vit D intoxication
HYPERCALCAEMIA OF MALIGNANCY
Tumour lysis syndrome
Bone metastasis
PRIMARY INCREASE IN BONE RESORPTION
Hyperthyroidism
Immobilisation
EXCESSIVE CALCIUM INTAKE
Milk-alkali syndrome
TPN
Causes of hypokalaemia (DIRE)
DIRE
Drugs (loop and thiazide diuretics)
Inadequate intake or Intestinal loss (D&V)
Renal tubular acidosis
Endocrine (Cushing’s and Conn’s syndromes)
Causes of hyperkalaemia (DREAD)
DREAD
Drugs (K-sparing diuretics and ACE inhibitors)
Renal failure
Endocrine (Addison’s)
Artefact (very commonly due to clotted sample)
DKA
What is raised urea indicative of?
Kidney injury or upper GI haemorrhage
Raised creatinine for kidney injury, low Hb for GI bleed
Types of AKI
Prerenal
Intrinsic renal
Postrenal
Biochemical disturbance of prerenal AKI
Urea rise > creatinine rise
Biochemical disturbance of intrinsic renal AKI
Urea rise < creatinine rise
Bladder or hydronephrosis not palpable
Biochemical disturbance of postrenal AKI
Urea rise < creatinine rise
bladder or hydronephrosis may be palpable depending on level of obstruction
Causes of prerenal AKI
Dehydration of any cause eg sepsis, blood loss
Renal artery stenosis (often triggered by drugs, ACEi or NSAIDs, effectively causing hypoperfusion of kidneys)
Causes of intrinsic renal AKI
INTRINSIC
Ischaemia (due to prerenal AKI causing acute tubular necrosis)
Nephrotoxic antibiotics
Tablets (ACEi, NSAIDs)
Radiological contrast
Injury (rhabdomyolysis)
Negatively bifringent crystals (gout)
Syndromes (glomerulonephrodites)
Inflammation (vasculitis)
Cholesterol emboli
Nephrotoxic antibiotics
Gentamicin
Vancomycin
Tetracyclines
Causes of postrenal AKI
IN LUMEN
Stone or sloughed papilla
IN WALL
Tumour (renal cell, transitional cell)
Fibrosis
EXTERNAL PRESSURE
BPH
Prostate cancer
Lymphadenopathy
Aneurysm
Markers of hepatocyte injury or cholestasis
Bilirubin
Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)
Alkaline phosphatase (ALP)
Markers of synthetic liver function
Albumin
Vitamin K dependent clotting factors measured via PT/INR
Vitamin K dependent clotting factors
II
VII
IX
X
Causes of raised alk phos
Any fracture
Liver damage (post-hepatic)
Cancer
Paget’s disease of the bone
Pregnancy
Hyperparathyroidism
Osteomalacia
Surgery
LFT derangement in prehepatic jaundice
Isolated raised bilirubin
LFT derangement in intrahepatic jaundice
Raised bilirubin
Raised AST/ALT
LFT derangement in posthepatic jaundice
Obstructive jaundice
Raised bilirubin
Raised ALP
Causes of prehepatic jaundice
Haemolysis
Gilbert’s and Crigler-Najjar syndromes
Causes of intrahepatic jaundice
Fatty liver
Hepatitis
Cirrhosis
Malignancy
Metabolic - Wilson’s disease/haemochromatosis
Heart failure causing hepatic congestion
Causes of posthepatic jaundice
OBSTRUCTIVE
IN LUMEN
Gallstones
Drugs causing cholestasis
IN WALL
Tumour (cholangiocarcinoma)
Primary biliary cirrhosis
Sclerosing cholangitis
EXTRINSIC PRESSURE
Pancreatic or gastric cancer
Lymphadenopathy
Causes of hepatitis and cirrhosis
Alcohol
Viruses (hepatitis A-E, CMV, EBV)
Drugs (paracetamol overdose, statins, rifampicin)
Autoimmune (primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune hepatitis)
Drugs causing cholestasis
Flucloxacillin
Co-amoxiclav
Nitrofurantoin
Steroids
Sulphonylureas
TFTs in primary hypothyroidism
Decreased T4
Increased TSH
Decreased T4 from thyroid causing compensatory increased TSH
Hashimoto’s thyroiditis, drug induced hypothyroidism
TFTs in secondary hypothyroidism
Decreased T4
Decreased TSH
Decreased TSH causing decreased T4
Pituitary tumour or damage
TFTs in primary hyperthyroidism
Increased T4
Decreased TSH
Increased T4 causing decreased TSH through negative feedback
Grave’s disease, toxic nodular goitre, drug induced hyperthyroidism
TFTs in secondary hyperthyroidism
Increased T4
Increased TSH
Increased TSH from pituitary causing increased T4
Pituitary tumour
Type 1 respiratory failure
Low or normal PaCO2
Fast/normal breathing
Caused by anything that damages heart or lungs causing SOB
Type 2 respiratory failure
High PaCO2
Slow/shallow breathing
COPD, neuromuscular failure or restrictive chest wall abnormalities
Respiratory acidosis
Low pH
High PaCO2
Normal or raised HCO3 (compensation)
COPD, neuromuscular failure or restrictive chest wall abnormalities
Respiratory alkalosis
High pH
Low PaCO2
Normal or reduced HCO3 (compensation)
Rapid breathing from disease or anxiety
Metabolic acidosis
Low pH
Low HCO3
Normal or reduced PaCO2 (compensation)
Lactic acidosis, DKA, renal failure
Metabolic alkalosis
High pH
High HCO3
Normal or raised PaCO2 (compensation)
Vomiting, diuretics, Conn’s syndrome
How to manage over anticoagulation with an INR 5-8 and no bleeding?
Omit warfarin for 2 days then reduce dose
How to manage over anticoagulation with an INR >8 and no bleeding?
Omit warfarin and give 1-5 mg PO vitamin K
How to manage over anticoagulation with an INR 5-8 and minor bleeding?
Omit warfarin and give 1-5 mg IV vitamin K
How to manage over anticoagulation with an INR >8 and minor bleeding?
Omit warfarin and give 1-5 mg IV vitamin K
How to manage over anticoagulation with major bleeding?
ie causing hypotension or bleeding into confined space (brain/eye)
Stop warfarin
Give 5-10 mg IV vitamin K
Give prothrombin complex
Gentamicin and vancomycin ADRs
Nephrotoxicity
Ototoxicity
ADR of any antibiotic, but mainly broad spectrum
C. diff colitis
ADRs of ACE inhibitors
Hypotension
Electrolyte abnormalities
AKI
Dry cough
ADRs of beta blockers
Hypotension
Bradycardia
Wheeze in asthmatics
Worsens acute HF
Improves chronic HF
ADRs of CCBs
Hypotension
Bradycardia
Peripheral oedema
Flushing
ADRs of diuretics
Hypotension
Electrolyte abnormalities
AKI
Subclass dependent effects
ADRs of heparins
Haemorrhage
Heparin-induced thrombocytopenia
ADRs of warfarin
Haemorrhage
ADRs of aspirin
Haemorrhage
Peptic ulcers
Gastritis
Tinnitus in large doses
ADRs of digoxin
Nausea
D&V
Blurred vision
Confusion
Drowsiness
Xanthopsia
Xanthopsia
Disturbed yellow/green visual perception including “halo” vision
ADRs of amiodarone
Interstitial lung disease
Thyroid disease
Skin greying
Corneal deposits
ADRs of lithium
EARLY
Tremor
INTERMEDIATE
Tiredness
LATE
Arrhythmias
Seizures
Coma
Renal failure
Diabetes insipidus
ADRs of antipsychotics haloperidol and clozapine
Dyskinesias
Agranulocytosis
ADRs of statins
Myalgia
Abdominal pain
Increased ALT/AST
Rhabdomyolysis
Drugs with narrow therapeutic index
Warfarin
Digoxin
Phenytoin
Theophylline
Drugs requiring careful dosage control
Antihypertensives
Antidiabetic drugs
GI bleeding caused by
NSAIDs
Lactic acidosis caused by
Metformin
Hypertensive crisis caused by
MAOIs
Sweating, flushing, nausea and vomiting caused by
Metronidazole
Disulfiram
Sedation caused by
Barbiturates
Opioids
Benzodiazepines
What drugs to avoid in peripheral vascular disease?
Beta blockers
ACEi cautioned in severe disease
What drug should be continued through intercurrent illness?
Prednisolone (in case of chronic adrenal suppression)
How many micrograms fentanyl/hour are equivalent to 60 mg oral morphine per day?
25 micrograms/hour
Drugs causing hyperkalaemia
Potassium-sparing diuretics
Beta blockers
ACEi/ARBs
Digoxin at toxic levels
Heparin
Trimethoprim and co-trimoxazole
Ciclosporin
Tacrolimus
Non-steroidal anti-inflammatory drugs (NSAIDs)
Drugs causing hypokalaemia
Laxatives (excessive use)
Thiazide and loop diuretics
High dose beta 2 agonists
Theophylline
High dose penicillins
Gentamicin
Amphotericin
Echinocandin antifungals
High dose insulin
Corticosteroids
Cisplatin
Sodium bicarbonate
Parecoxib
Vitamin K BNF
Phytomenadione
Drug induced extrapyramidal side effects/Parkinsonism treatment
Procyclidine hydrochloride
Not tardive dyskinesia
Tardive dyskinesia treatment
Tetrabenazine
How many mg of oral morphine/day are equivalent to 25 microgram fentanyl/hour?
60 mg