Drugs Flashcards
How do TCAs treat depression
by increasing levels of serotonin and norepinephrine or just norepinephrine within the synaptic cleft, thus increasing the activity of postsynaptic neurons.
Indications to use TCAs
Depression (SSRI still first line)
OCD
Migraines
Peripheral neuropathy
What are the unwanted side effects of TCAs
- 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
Dose and regime to initiate warfarin (AF vs DVT)
- 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.
What medications interact with warfarin
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).
How to monitor lithium levels, and what do the levels indicate
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
how to withdraw a benzodiazepine?
The dose should be withdrawn in steps of about 1/8 (range 1/10 to 1/4) of the daily dose every fortnight.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
SSRI side effects
Sexual dysfunction 30%
gi upset 10-30%
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
What is the role of buspirone
- 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
Side effects of benzos
Sedation
cognitive impairment and ataxia in elderly people
amnesia
Dependence / addiction
First line stimulant medication for ADHD
methylphenidate
- Short acting: MORN + MIDDAY dosing
- Long acting: MORN (however may impact sleep)
Dexamphetamine
- MORNING DOSING ONLY
Side effects of stimulants methylphenidate and dexamphetime
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
Meds likely to cause falls
- 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
Best antipsychotics for the elderly
Quetiapine or risperidone
sedating antihistamine
promethazine
What medications can cause rhabdomyolysis w statins and why
statins break down muscle. These medications can inhibit the metabolism of statins (CYP3A4 inhibitor)
- macrolides
- oral antifungals
- ## non-dyhydro CCBs
Side effects of bupropion
used for smoking cessation and depression
Insomnia (30-40%)
dry mouth (10%)
nausea
do not use in cirrhosis, epilepsy, during drug withdrawal
What antibiotics should be avoided in a patient on methotrexate and why
trimethoprim and co-trimoxazole
due to the risk of bone marrow atresia
Contraindications to NOACs
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
drugs that cause hyponatraemia
diuretics (thiazide) and SSRIs
nsaids, ACE/ARBs, antipsychotics (polydipsia)
(non specific fatigue/nausea sx)
loop diuretics can caue HYPERNa
side effects of phosphodiesterase-5 inhibitors
flushed face, headaches, blocked nose, altered colour vision (mainly with sildenafil) and gastric reflux.
do not mix with nitrates for risk of large BP drop
Oral to Subcutaneous morphine
2:1
the subcutaneous dose is half the oral dose
(so if converting to a syringe driver then half the total daily dose of morphine or oxycodone)
Codeine to Morphine ratio
10:1
tramadol to Morphine
10:1
contraindication to triptans
patients with a history of, or significant risk factors for, ischaemic heart disease or cerebrovascular disease
adverse effects of triptans
‘triptan sensations’ - tingling, heat, tightness (e.g. throat and chest), heaviness, pressure
What is the long term issue with levodopa
effectiveness (after 2 yrs) and reliability/motor fluctuations (4-5yrs)
long term patients usually need higher doses/multiple drugs and experience motor complications and drug-induced dyskinesias.
COCP and cancer risk
increased risk of breast and cervical cancer
protective against ovarian and endometrial cancer
B and C, O and E
how does allopurinol work
xanthine oxidase inhibitor
stops the metabolism of purines to uric acid
Main side effects of ACEi’s
Dry cough - 15% of patients and may occur up to a year after starting treatment
Angioedema - up to a year post starting
Hyperkalemia
Hypotension - especially after the first dose
Renal impairment
Main side effects of CCBs
Peripheral oedema
Headache and flushing
Constipation
Dizziness or lightheadedness
Bradycardia (verapamil or diltiazem)
Gingival hyperplasia
Beta blocker common side effects
Fatigue and weakness
Bradycardia
Cold hands and feet
Dizziness
Shortness of breath (especially in patients with asthma or COPD)
ARB side effects
hypotension
dizziness
hyperkalaemia
