Pharmacology Flashcards
Warfarin
Vitamin K antagonist
Reversal: Vit K
INR target 2.5-3.5 if high risk
Interactions:
-diet: CHANGE in diet important to monitor e.g. green leafy vegetables and beef liver, high in Vit K.
-pharmacokinetic: CYP450 [CYP 2CP (more) and CYP 3A4 (less)]
. inhibitor (increases warfarin): metronidazole, celecoxib, diltiazem, amiodarone
. inducer (decreases warfarin): anti-epileptics.
-pharmacodynamic: increased bleeding risk with anti-platelets e.g. NSAIDs, SSRIs and medications that increase risk of falls.
Protein binding
-saturable process
-albumin
-glycoproteins
Albumin + acidic drugs:
aspirin, warfarin, penicillin, sulphonamides.
Glycoprotein + basic drugs:
quinidine, propanolol, lignocaine.
Digoxin
Level 6-12hrs post loading dose
Normal range 0.5-2.0
Toxicity: ventricular arrythmia, visual disturbance, GI, headache.
Contraindications: MI, Wolff-parkinson white (narrow PR int, delta wave and prolonged QRS + tachyarrythmia), electrolyte disturbance, myocarditis.
Interactions: macrolides, azoles, loop diuretics.
CYP450 table
-clozapine
-phenytoin/warfarin
-clopidogrel
-codeine, tramadol, tamoxifen
-warfarin, ciclosporin
-rifampicin (general)
CYP1A2: clozapine level increased by smoking cessation.
CYP2C9: Phenytoin / warfarin / NSAIDs increased by fluconazole.
CY2C19: clopidogrel decreased by carbamazepine and progestins.
CD2D6: codeine, tramadol, tamoxifen decreased by dexamethasone, haloperidol and increased by fluoxetine.
CYP3A: warfarin, ciclosporin increased by macrolides, azoles and decreased by anti-epileptics, St John’s wort.
Rifampicin in general, decreased availability of other drugs.
TPMT
Metabolises AZA
Decreased TPMT activity means decreased AZA dose
Allopurinol inhibits xanthine oxidase
-inhibits metabolism of AZA and 6MP
-reduce to 25% normal dose
Adverse effects
Rosiglitazone (antihyperglycemic) - CVD risk and weight gain.
GLP-1 agonists (semaglutide) / DPP4 (linagliptin) inhibitors - pancreatitis, thyroid tumours.
SGLT2 inhibitors (flozin) and DKA, fournier’s gangrene.
Zoledronic acid - osteonecrosis of jaw.
TNFa inhibitors and severe bacterial infections/TB and hepatosplenic t-cell lymphoma.
Infliximab and non-melanoma skin cancers esp psoriasis pts.
Immunotherapy and autoimmune disease (thyroid, addisons, T1DM).
Atypical antipsychotics- metabolic syndrome.
Clozapine - constipation, eosinophilic myocarditis, blood dyscrasias.
Venlafaxine- stress cardiomyopathy (women, emotional distress)
Citalopram/escitalopram - QT prolongation.
Topiramate- visual field defects.
Anticonvulsants - suicidality.
Valproate pregnancy, birth defects (neural tube), autism, intellectual disability.
PPI- hypomagnesemia, decreased BMD.
Codeine ultra-rapid metabolisers.
Dabigatran - oesophageal ulceration.
Fluoroquinolones- aortic aneurysm, dissection.
Tocilizumab / MTX / Fingolimod - hepatotoxicity.
HAGMA v NAGMA
Metabolic acidosis
HAGMA
Methanol, metformin
Uraemia
DKA
Paraldehyde, phenformin
Isoniazid, iron, ibuprofen
Lactic acidosis, lithium
Ethylene glycol
Salicylates
NAGMA
Ureteral diversion
Saline
Exogenous acid
Diarrhoea
Carbonic anhydrase inhibitors (acetazolamide)
Adrenal insufficiency
Renal tubular acidosis
Steven Johnsons/toxic epidermal necrolysis.
DRESS- drug reaction with eosinophilia and systemic symptoms and durg-induced hypersensitivity syndrome.
SJ/TEN: HIV related, HLA related, meds, vaccinations, infection (mycoplasma, CMV).
-cotrim (dapsone, alternative)
-beta-lactam
-anti-convulsants (lamotrigine, carbamazepine, phenytoin, phenobarbitone)
-allopurinol
-paracetamol
-NNRTI (nevirapine)
-NSAIDs (oxicam)
Dx: skin bx, serum granulysin
Tx: supportive, ciclosporin
DRESS:
Widespread inflammation (hepatitis, interstitial nephritis, myocarditis/pericarditis, interstitial pneumonitis, meningitis/encephalitis, gastroenteritis, pancreatitis, thyroiditis, diabetes, myositis, uveitis).
Tx: steroids, ciclosporin, IVIG, PLEX.
Cholinergic crisis
-Organophosphates or carbamate
-Pyridostigmine
MORE LIQUID
SLOWING DOWN
MORE CRAMPING
MORE LIQUID:
Salivation
Lacrimation
Urinary and faecal incontinence
Emesis
Diaphoresis
Pulmonary oedema
SLOWING DOWN:
Confusion
CNS depression
Weakness
Miosis
Bradycardia or tachycardia
Hypotension
MORE CRAMPING:
Abdo
Muscle fasciculations
Seizures
