Pharmacology

Question 1

Name some drugs with a strong anti-cholinergic effect

Answer 1

Amitriptyline, imipramine, oxybutynin, paroxetine, procyclidine, promethazine

Question 2

What is the link between anti-cholinergics and dementia?

Answer 2

regular anticholinergic use = increased risk of dementia. 1.5 fold increase after 3 years of use. Dose-dependent relationship. Only association not causation has been proven.

Question 3

Name the four DOAC’s

Answer 3

Dabigatran, rivaroxaban, Apixaban and edoxaban.

Question 4

What are all DOAC’s licensed for?

Answer 4

Stroke prevention in non valvular AF. Treatment of venous thromboembolism. Prevention of recurrence of VTE.

Question 5

Who cannot use DOAC’s?

Answer 5

Those with mechanical heart valves. Those with anti-phospholipid syndrome.

Question 6

How is renal function assessed prior to prescribing DOAC’s?

Answer 6

Using creatinine clearance, not eGFR

Question 7

Why do we now use DOACs rather than warfarin in AF?

Answer 7

-They are easy to use because they need no monitoring.
-There are relatively few food and drug interactions compared with warfarin.
Renal excretion means there is concern about use in renal impairment (see above table for use in renal impairment).
-Onset of action is fast (2–3h) and half-life is around 12h (longer in renal impairment).
The short half-life means that one missed dose matters as they clear relatively rapidly from the system. This makes DOACs unsuitable if compliance is erratic because the anticoagulation effect will also be erratic.
-Reversal agents are now available for apixaban, dabigatran and rivaroxaban.

Question 8

What formula is used for calculating creatinine clearance?

Answer 8

• The Cockcroft-Gault formula.

Question 9

When might eGFR not accurately interpret renal function? and what should we consider using as well?

Answer 9

• In those >75
• In those with a BMI <18 or >40
• Whenever you prescribe a DOAC
• If prescribing a renally excreted drug with a narrow therapeutic index (e.g digoxin, sotalol)
  Consider using creatinine clearance- The Cockcroft-gault formula.

Question 10

What are the indications for gabapentinoids?

Answer 10

Gabapentin- epilepsy, peripheral neuropathy
Pregabalin- as above + generalised anxiety.

Question 11

How effective are gabapentinoids for pain?

Answer 11

For neuropathic pain they can offer effective pain relief for some and should still be considered as first line options.
- fibromyalgia- absence of evidence, limited benefit.
- Demonstrated to be ineffective for low back pain, sciatica, spinal stenosis and migraine.

Question 12

What are the risks of side effects with gabapentinoids?

Answer 12

Nearly 2/3 experience dizziness/drowsiness/oedema. We should encourage patients to report them and if significant taper/stop them.

Question 13

How do beta blockers work?

Answer 13

They block the beta-adrenoceptors in the heart, peripheral vasculature, bronchi, pancreas and liver

Question 14

What does it matter if beta blockers are water soluble?

Answer 14

They are less likely to enter the brain and less likely to cause sleep disturbance and nightmares. Also will be excreted by the kidneys and dosage reduction may be needed in renal impairment

Question 15

When are beta blockers contraindicated?

Answer 15

Second or third degree heart block. Worsening unstable heart failure

Question 16

Which beta blockers are cardio selective and why might this be useful?

Answer 16

Atenolol, bisoprolol fumarate, metoprolol, nevivolol. They have a lesser effect on the airways and less likely to cause bronchospasm (still can to a degree) so can be useful if needed in people with asthma/COPD

Question 17

What are common side effects of beta blockers?

Answer 17

Fatigue, coldness in the extremities and sleep disturbance with nightmares.

Question 18

Why are beta blockers used in angina?

Answer 18

They reduce cardiac work and increase exercise tolerance as well as relieve symptoms.