Pharmacology Flashcards
What pain killer has a dangerous interaction with lithium, in terms of it’s excretion?
NSAIDs- competes for active transport out the kidneys so less lithium excreted
What type of laxative should be given for those on morphine?
Stimulant laxative- ie senna
As opioids reduce motility
What is the danger of giving SSRIs (like citalopram) with antiplatelet drugs?
Seratonin is a mild antiplatelet, slightly increases risk of bleed
What needs to be on a controlled drug prescription?
On all prescriptions: Name + address, Dr name + address, signed
Drug name + strength + preparation
Dose + frequency
Total number of tablets/volume given
Written in numbers and words
Why is tramadol different in mechanism to other opioids?
Acts on seratonin and noradrenergic receptors unlike other opioids so can lower seizure thresholds (avoid in epileptic patients) and puts at risk of seratonin syndrome
Drugs causing urinary retention:
Anticholinergics (antipsychotics, antidepressants, respiratory gents) Anaesthetic agents Analgesia- morphine Alpha-adrenoreceptor agonists (hypertension) Anti-inflammatories Anxiolytics (benzodiazepines) Antihistamines Alcohol Antihypertensive- Ca channel blockers
Which antibiotics may have cross-reactions with penicillins, causing anaphylactic reactions is pen-allergic?
Carbopenems (meropenem)
Cephalosporin
Which antibiotic causes tendontis?
Ciprofloxacin
What antibiotics put patients at higher risk of C Diff infections?
Ciprofloxacin
Cephalosporin
What is the problem with giving nitrofurantoin in a patient with a low GFR <30?
Doesn’t get excreted enough into the urine to become concentrated and give a therapeutic dose, so patient gets subtherapeutic dose if clearance is poor
What’s the difference between spironolactone, eplerenone compared to amiloride?
All work as aldosterone pathway antagonists, but spironolactone acts on the receptor and amiloride acts on the ENaC channel directly.
Which UTI antibiotic causes high potassium?
Trimethoprim- blocks ENaC channels.
Side effects of steroids
Diabietes, Hypertension
Cushing’s, Addisonian crisis
Osteonecrosis, osteoporosis
Proximal myopathy
Pancreatitis, infection
Cataracts, glaucoma
Buffalo hump, acne, striae
Which receptors does tamulosin act on?
Alpha 1 antagonist
Benign prostatic hyperplasia
Prevent smooth muscle constriction
What are beta 1 + beta 2 agonists used for?
Dobutamine- beta 1 agonism (raise BP in very sick patients)
Salbutamol- beta 2 agonism (asthma)
Which drugs can cause constipation:
Opiates Ca-channel antagonists Antidepressants, antiepileptics Iron/calcium supplements Diuretics
Causes of gynaecomastia
D - Digoxin I - Isoniazid S - Spironolactone C - Cimetidine O - Omeprazole/Oestrogens M - Methyldopa T - Tricyclic antidepressants V - Verapamil
What features on the U+Es/FBC indicate there is a CKD rather than AKI?
Anaemia
Low calcium, high phosphate (no vit D, so low calcium absorption and lack of phosphate excretion)
Signs of Digoxin toxicity:
Fatigue + confusion
N+V
Yellow vision
Bradycardia or tachycardia, AV block every kind of dysarrhythmia
Drug causes of lung fibrosis:
BAN MS Bleomycin- chemo Amiodarone Nitrofurantoin long term- chronic UTI Methotrexate Sulfasalazine, rarely statins
What happens in Gilbert’s disease?
Bilirubin normally conjugated by liver, so it is water sluble and can be secreted into bile and the duodenum.
Gilbert’s reduced activity of gluconryltransferase- less conjugation of bilirubin so it isn’t excreted into urine (unconjugated bilirubin is insoluble), can get jaundice from high bilirubin
Vincristine SE (chemo)
Peripheral neuropathy
How does Isoniazid cause peripheral neuropathy?
Vit B6 deficiency
Which immunosuppressant causes ulcerative stomatitis (inflammation of gum linings)
Methotrexate
Drug causes of long QT syndrome
SHAME AT
SSRIs HAloperidol Methadone Erythromicin Amiodarone Tricyclic antidepressants
Which beta blocker prolongs QT interval?
Sotolol
Name the mechanism of the following Parkinson’s drugs:
- Ropinirole
- Rasagiline
- Entacapone
- Benzhexol
- Dopamine agonist (also pramipexole)
- MAO-B inhibitor, reduces DA breakdown at presynaptic terminal (also selegiline)
- COMT inhibitor, reduces DA breakdown in synapse and on postsynaptic terminal
- Anticholinergic, reduces tremor by decreasing muscle activation by nAChR
How does N-acetylcysteine help prevent damage in a paracetamol overdose?
The body runs out of glutathione to be conjugated with a toxic paracetamol metabolite, so the metabolite builds up.
However NAC provides more glutathione so the metabolite may be neutralised before it can cause any toxic damage
Summarise the renin angiotensin system effects
Renin (juxtaglomerular cells-kidney) converts Angiotensinogen (from liver) into Angiotensin I
Which is converted into Angiotensin II by ACE (lungs)
AT-II vasoconstricts arterioles, increases ADH and prompts aldosterone secretion (from adrenals)
Aldosterone increases ENaC expression (more Na+, less K+)
What effect would thiazide diuretics have on calcium levels?
Thiazides raise Ca+ levels
By blocking Na/Cl cotransporter there’s less Na in tubular cells.
On the side of the cell near capillaries (not the luminal side) there’s a transporter that swaps 3Na into the tubular cell for every Ca it moves out of the cell and into the interstitium.
Less Na in the cell, more active transporter, more Ca moved into capillaries
How does Clopidogrel and Dipyridamole prevent platelet aggregation?
The resting state of platelets in maintained by a cAMP-activated calcium channel that causes efflux of Ca+ from the platelet keeping intracellular levels low, preventing activation.
Dipyridamole inhibits phosphodiesterase to maintain cAMP levels and keep Ca+ inside low
Clopidogrel inhibits the ADP receptor, this receptor would otherwise inhibit adenyl cyclase and break down cAMP
How does N-acetylcysteine help prevent damage in a paracetamol overdose?
The body runs out of glutathione to be conjugated with a toxic paracetamol metabolite, so the metabolite builds up.
However NAC provides more glutathione so the metabolite may be neutralised before it can cause any toxic damage
Summarise the renin angiotensin system effects
Renin (juxtaglomerular cells-kidney) converts Angiotensinogen (from liver) into Angiotensin I
Which is converted into Angiotensin II by ACE (lungs)
AT-II vasoconstricts arterioles, increases ADH and prompts aldosterone secretion (from adrenals)
Aldosterone increases ENaC expression (more Na+, less K+)
What effect would thiazide diuretics have on calcium levels?
Thiazides raise Ca+ levels
By blocking Na/Cl cotransporter there’s less Na in tubular cells.
On the side of the cell near capillaries (not the luminal side) there’s a transporter that swaps 3Na into the tubular cell for every Ca it moves out of the cell and into the interstitium.
Less Na in the cell, more active transporter, more Ca moved into capillaries
How does Clopidogrel and Dipyridamole prevent platelet aggregation?
The resting state of platelets in maintained by a cAMP-activated calcium channel that causes efflux of Ca+ from the platelet keeping intracellular levels low, preventing activation.
Dipyridamole inhibits phosphodiesterase to maintain cAMP levels and keep Ca+ inside low
Clopidogrel inhibits the ADP receptor, this receptor would otherwise inhibit adenyl cyclase and break down cAMP
Main side effect issue that needs to be monitored with ciclosporin?
Nephrotoxicity
Check creatinine every two weeks for first 3 months of treatment
Receptors that tramadol exerts an effect on?
Mu-opioid R agonist SSRI + 5-HT R antagonist Noradrenaline reuptake inhibitor NMDA R antagonist NACh R antagonist Muscarinic ACh R antagonist
Which opioids can precipitate serotonin syndrome?
Fentanyl and Tramadol
1st line antiemetic in pregnancy?
Antihistamine like cyclizine antiemetic
More experience, no evidence or teratogenicity
Preferred anti-emetic for chemo?
Visceral and chemoreceptor trigger zone nausea is mediated by serotonin and dopamine.
5-HT strongly involved in chemo-nausea so
Metoclopramide
What situation is metoclopramide less useful for?
Post-op nausea, for some reason despite it being a anti-dopaminergic agent it works less well?
Good for chemo-induced nausea though
Which antiemetics can cause
- Prolonged QT
- Parkinsonian side effects
- Worsening of bowel obstruction
- 5-HT antagonists and DA antagonists like ondansetron (5-HT) and metoclopramide (DA)
- DA antagonists (prochlorperazine, metoclopramide, NB domperidone doesn’t cross BBB, less likely to cause)
- DA antagonists (increases gut motility)
Hierarchy of Rx in type 2 diabetes?
Diet
Metformin
Add sulfonylura (gliclazide) or DPP-4 inhibitor (sitagliptin) or glitazone
Triple therapy or insulin
(No glitazone if LVF)
How does Rx of COPD differ depending on whether they have an FEV >50% or below 50%?
All get a short acting b-agonist or anti-muscarinic
Mild/moderate >50% = LABA or LAMA, then add steroid, then all 3 (stepwise approach)
Sever <50% = LAMA or LABA + steroid, then all 3 (jumps a step)
When would you give HRT via the vaginal route rather than transdermally?
For urogenital atrophy associated with the menopause
What is the benefit of giving HRT cyclically, continuously or without progesterone?
No progesterone- increased risk of endometrial cancer only indicated for hysterectomy patients
Cyclical HRT- still have periods (given if patient is still having periods)
Continuous HRT- no periods (only appropriate if post-menopausal + no periods in 1 year)
Name some common SSRIs, SNRIs and TCAs:
Depression Rx
1st: SSRIs- Fluoxetine, Citalopram, Sertraline, Paroxetine
2nd: SNRIs- Venlafaxine, Duloxetine
3rd: TCAs- Amitriptyline
1st line drug for high triglycerides in isolation (no raised cholesterol/LDLs)?
Fibrates- gemofibrozil, ciprofibrate, fenofibrate
Act in liver to reduce cholesterol synthesis, reducing vLDL secretion and increasing uptake from blood, increasing HDL plasma levels
Not to be used with statins
Drug causes of hypocalcaemia:
HypO:
Someone has CALled, loop over to the phone, pick up the phen
Loop diuretics
Bisphosphonates
Phenytoin
Drugs affected by cyp450:
COWEST
Ciclosporin Oral contraceptives Warfarin Epileptics Statins Theophylline
Causes of hyperkalaemia:
N SAID:Tri have Tact in the Cycles of Parin UREA
NSAID, Trimethoprim, Tacrolimus, Ciclosporin, Heparin, Sulphonylurea
ACEi, K+ sparing
Causes of agranulocytosis:
Carbamazepine
Colchicine
Carbimazole
Clozapine
Causes of liver fibrosis:
MAMI
Methotraxate
Amiodarone
Methyldopa
Isoniazid
Causes of gynaecomastia
DISCO MTV:
Digoxin Isoniazid Spironolactone Cimetidine Oestrogen
Methotrexate
TCAs
Verapamil
Causes of Long QT:
Macrolide Antipsychotic TCAs Histamine SSRI
SIADH:
Carbamazepine
SSRIs
Causes of neuropathy
MICE NAP
Methotrexate Isoniazid Ciclosporin Ethanol Nitrofurantoin Amiodarone Phenytoin/Penicillamine
Indications for anti-digoxin antibody:
Dangerous arrhythmias: VT, VF, 3rd degree heart block
K+ above 6
Digoxin above 7.8ng/mL 6 hours later
Antidote for arsenic?
Dimercaprol
Drug causes of diarrhoea:
COT (babies poo):
Colchicine
Orlistat
Theophylline
Antidepressant that particularly may cause constipation?
Tricyclics- anticholinergic effects
Also watch out for oxybutinin, given for urge incontinence
Drug causes of lupus?
HIP
Hydralazine
Isoniazid
Procainamide (sodium channel blocker antiarrhythmic)
How does suxamethonium work?
Partial agonist of acetylcholine receptors, depolarises the post-synaptic membrane
Rapidly inactivated using plasma cholinesterases
SEs: high K+, muscle pains post-op
What are the two mechanisms of neuromuscular blockers used in surgery and how are they reversed?
Partial ACh receptor agonists- depolarise post-synaptic membrane
(suxamethonium)
Competitive antagonists of AChR- compete with ACh at the neuromuscular junction
(Rocuronium, sugammadex, vecuronim, atracurium)
Which antibiotics are safe to prescribe to patients with porphyrias?
Penicillins only pretty much.
Which drugs can displace sodium valproate and digoxin from protein-carriers in the blood?
NSAIDs
Aspirin
Which drugs cause oesophageal irritation, and what are the two mechanisms by which they do this?
Direct inflammation: alendronic acid, tetracycline, sando-K
Lowering oesophageal tone: nitrates, Ca channel blockers
Which immunomodulator drugs are associated with the following side effects:
A. Pancreatitis
B. Oligozoospermia
A. Azathioprine or mercaptopurine (it’s prodrug)
B. Sulfasalazine
Rx of Whipple’s disease?
PAs + macrophages
Gram positive bacteria, trophyerma whipplei Causes 1. Malabsorption 2. Arthropathy 3. CNS disease + cerebellar signs
Rx: ceftriaxone- crosses BBB
Long term- trimethoprim or doxycycline
Rx of constipation and order of medication trials:
- Lifestyle and drug reconciliation
- Stimulant laxative- senna
- Osmotic- movicol or lactulose
- Glycerine suppository
- Phosphate enema
- Manual evacuation
