10 ways to kill a patient

Question 1

Methotrexate and Trimethoprim

Answer 1

Problem: both drugs block DHFR
 Consequence: severe bone marrow
depression

Question 2

Trimethoprim indications

Answer 2

DHFR
 Main indications are:
o UTI
o MRSA
o In combination with sulphamethoxazole

Question 3

Methotrexate indications

Answer 3

Main indications are:
o Rheumatoid arthritis
o Psoriasis
o Cancer chemotherapy

Question 4

Abx for UTI

Answer 4

Trimethoprim
 Ciprofloxacin
 Amoxicillin
 Erythromycin

Question 5

Allopurinol

Answer 5

For gout, renal stones and some cancer
treatment
 Used especially for n acute attack or
prophylaxis of gout

Question 6

Allopurinol mechanism

Answer 6

Inhibits formation of uric acid in the body (by

inhibiting xanthine oxidase)

Question 7

Azathiprine

Answer 7

An immunosuppressant

 Used mainly in rheumatoid arthritis, Crohn’s disease, ulcerative disease and renal transplants.

Question 8

azathioprine and allopurinol

Answer 8

 Problem: allopurinol inhibits xanthine
oxidase, increasing 6-MP levels
 Consequence: severe bone marrow
depression

Question 9

erythromycin, warfarin and atorvastatin

Answer 9

Problem: enzyme inhibition by erythromycin

 Consequence: reduced metabolism of warfarin and statin causing a raised INR and CK (due to increased muscle break down from statin)

Question 10

Enzyme inducers

Answer 10

P- phenytoin
 C-carbamazepine
 A-alcohol
 R-rifampicin
 B-barbiturates
 S-sulphonylureas

Question 11

Enzyme inhibitor

Answer 11

Examples are: (remember ICE DOVES)
 I-isoniazid
 C-ciprofloxacin
 E-ethanol (acutely)
 D-disulfiram
 O-omeprazole
 V-valporate
 E-erythromycin

Question 12

Beta blockers

Answer 12

Bind to and inhibit beta-AR
o Reduces sinus rate
o Reduces conduction through SAN

Question 13

Calcium Channel Blockers

Answer 13

 Non-dihyrdopyridines including diltiazem or verapamil (not amliodipine)
 Inhibit L-type calcium channels
 Reduce conduction through AVN

Question 14

verapamil and metoprolol

Answer 14

Problem: inhibition of both SAN and AVN

 Consequence: severe bradycardia

Question 15

Lithium:

Answer 15

Mood stabiliser
 Renal excretion (so dependant on eGFR)
 Monovalent cation is urine (same as sodium- Na + )
 Can therefor be reabsorbed in the place of sodium

Question 16

Two major causes of drug related toxicity

Answer 16

Increase reabsorption of lithium (diuretics, mainly thiazide, reduce sodium reabsorption
and increase lithium absorption)

o Reduce excretion (NSAIDs and ACEIs reduced lithium excretion)

Question 17

INTERACTION: lithium and any thiazide diuretic, NSAID or ACE-I

Answer 17

Problem: increased lithium reabsorption/reduced excretion

 Consequence: lithium toxicity

Question 18

5-fluoroquinolones

Answer 18

5-fluoroquinolones (and other drugs that can
cause seizures)
 Active against both gram +/- organisms
 Examples include:
o Ciprofloxacin
o Levofloxacin
o Norfloxacin

Question 19

INTERACTION: drugs that lower the threshold

for a seizure

Answer 19

Quinolones
o Carbapenems (meropenem)
o Penecillins (benzylpenecillin)
o Tramadol
o Nefopam
o Antiarrhythmic drugs that
interact with AEDs
 Problem: lowered seizure threshold
 Consequence: tonic-clonic seizure

Question 20

Therapeutic drug monitoring 3 x anitbiotics

Answer 20

Gentamicin (for gram -, osteomyelitis, IE, PID, meningitis, pneumonia, UTI, sepsis)
 Teicloplanin (for MRSA)
 Vancomycin (for cellulitis, sepsis, endocarditis,
osteomyelitis, arthritis)

Question 21

Therapeutic Drug monitoring

Answer 21

Gentamicin (for gram -, osteomyelitis, IE, PID, meningitis, pneumonia, UTI, sepsis)
 Teicloplanin (for MRSA)
 Vancomycin (for cellulitis, sepsis, endocarditis,
osteomyelitis, arthritis)
 Digoxin (3 rd choice for AF (BB or CCB first), also for
HF or atrial flutter)
 Theophylline (mainly for asthma or COPD, relaxes
bronchial smooth muscle)
 Phenytoin (antiepileptic and anticonvulsant)
 Carbamazepine (neuropathic pain, seizures and diabetic neuropathy)
 Valproate (antiepileptic)

Question 22

INTERACTION: drug toxicity

Answer 22

INTERACTION: drug toxicity
 These drugs therapeutic index
must be closely monitored
 Problem: easy toxicity
 Consequence: usually AKI

Question 23

INTERACTION: penicillin allergy and Carbapenems

Answer 23

Carbapenems (broad spectrum antibiotics, used for multi-drug resistant bacteria

These drugs are structurally similar to penicillin as they still have a beta-lactam ring, so there is some cross-
reactivity in penicillin allergic patients
 Impenem
 Ertapenem
 Meropenem
In a potential penicillin allergy you must establish whether it is a true allergy or immune mediated
response (rash or swelling).
There is a small risk of cross-reactivity with:
 Cephalosporins (cefuroxime, ceftriaxone)
 Carbapenems

Question 24

MAO inhibitors and TCAs

Answer 24

Problem: build up of NT and 5HT in
presynaptic cleft
 Consequence: hypertensive crisis
(causes impairment of one or more
organ with potential to cause
permanent damage)

Question 25

Monoamine Oxidase Inhibitors:

Answer 25

Leads to increased concentration of monoamines, NT

and 5HT within pre-synaptic bulb

Question 26

Tricyclic Antidepressants:

Answer 26

Also increase NA and 5HT concentrations

 Causes sympathetic surge

Question 27

INTERACTION: Vincristine given intra-thecally

Answer 27

Problem: vincristine related neurotoxicity

 Consequence: patient death