Drugs

Question 1

How do TCAs treat depression

Answer 1

by increasing levels of serotonin and norepinephrine or just norepinephrine within the synaptic cleft, thus increasing the activity of postsynaptic neurons.

Question 2

Indications to use TCAs

Answer 2

Depression (SSRI still first line)
OCD
Migraines
Peripheral neuropathy

Question 3

What are the unwanted side effects of TCAs

Answer 3

• Sedation
• Orthostatic hypotension
• Atropine like symptoms: dry mouth, tachycardia, urinary retention, confusion, and hallucinations
• serotonin syndrome: flushing, rigidity, hyperthermia, coma, agitation, seizures
• QT prolongation + arrhythmias

Question 4

Dose and regime to initiate warfarin (AF vs DVT)

Answer 4

• Low thrombosis risk (AF): Start with 3 mg daily, with baseline and weekly INR testing for the first two weeks.
• High thrombosis risk (DVT): Start with 5 mg daily and concurrent LMWH (enoxaparin), with daily INR testing for the first five days.

adjust doses at least four days apart to allow for changes in steady state.

Question 5

What medications interact with warfarin

Answer 5

Numerous medicines interact with warfarin

either by altering the INR (e.g. antibiotics) or by increasing the risk of bleeding (e.g. NSAIDs or SSRIs).

Question 6

How to monitor lithium levels, and what do the levels indicate

Answer 6

Serum concentration should be measured five to seven days after dose initiation or dose change,** then every six months**

blood sample should be taken 12 hours after dosing.

0.6 – 0.8 mmol/L - for stable patients
0.8 – 1.0 mmol/L - for acute mania or relapse
> 1.2 mmol/L - toxic
> 2.0 mmol/L - medical emergency

Question 7

how to withdraw a benzodiazepine?

Answer 7

The dose should be withdrawn in steps of about 1/8 (range 1/10 to 1/4) of the daily dose every fortnight.

If experiencing difficulty switch patients to the equivalent dose of diazepam

reduce dose of diazepam every 2-3 weeks in steps of 2 or 2.5 mg
time needed for withdrawal can vary from 4 weeks to a year or more

Question 8

SSRI side effects

Answer 8

Sexual dysfunction
Transient: insomnia, increased suicidal thoughts, anxiety and nausea

Discontinuation SE’s: dizziness, nausea, anxiety, vivid dreams and headache

*Paroxetine has more discontinuation Sx due to a short half life, fluoxetine has less due to a long half life

Question 9

What is the role of buspirone

Answer 9

• Second line medication (after antidepressants) for anxiety when other agents are contraindicated or have failed
• lack of withdrawal symptoms, low potential for abuse / dependence and it doesnt mix with alcohol or hypnotics (unlike benzos
• as effective as benzodiazepine for GAD (but may be less effective if pt recently used benzos
• Special authority

Question 10

Side effects of benzos

Answer 10

Sedation
cognitive impairment and ataxia in elderly people
amnesia
Dependence / addiction

Question 11

First line stimulant medication for ADHD

Answer 11

methylphenidate
- Short acting: MORN + MIDDAY dosing
- Long acting: MORN (however may impact sleep)

Dexamphetamine
- MORNING DOSING ONLY

Question 12

Side effects of stimulants methylphenidate and dexamphetime

Answer 12

Reduced appetite - can lead to weight loss and reduced height
Insomnia
Nervousness
GI sx
Tics, mood changes

Height reduction is reversible and improves once medication is stopped

Question 13

Meds likely to cause falls

Answer 13

• Benzos
• Antidepressants (especially TCA’s, do not use amitriptyline in elderly**)
• sedatives (zopis, opiods)
• antipsychotics

Try switch amitrip to nortriptyline or an alternative agent in elderly

Question 14

Best antipsychotics for the elderly

Answer 14

Quetiapine or risperidone

Question 15

sedating antihistamine

Answer 15

promethazine

Question 16

What medications can cause rhabdomyolysis w statins and why

Answer 16

statins break down muscle. These medications can inhibit the metabolism of statins (CYP3A4 inhibitor)

• macrolides
• oral antifungals
• ## non-dyhydro CCBs

Question 17

Side effects of bupropion

used for smoking cessation and depression

Answer 17

Insomnia (30-40%)
dry mouth (10%)
nausea

do not use in cirrhosis, epilepsy, during drug withdrawal

Question 18

What antibiotics should be avoided in a patient on methotrexate and why

Answer 18

trimethoprim and co-trimoxazole

due to the risk of bone marrow atresia

Question 19

Contraindications to NOACs

Answer 19

Active serious bleeding
Certain bleeding-associated co-morbidities, e.g. severe thrombocytopenia or severe anaemia
History of recent high-risk bleeding event (ICH)
Pregnancy
Mechanical heart valves
Moderate-to-severe mitral stenosis
Severe liver disease

Dabi <30 CrCl
Riva <15 CrCl