Pharmacology Flashcards
if someone has renal failure can they take drugs that have a narrow or high therapeutic index?
high therapeutic index, if a drug has a narrow therapeutic index then can cause toxicity or death
what does renal impairment do to narrow index drug half lifes?
increases them, eg gentamicin half life will increase from 2.5h to 50h
what affect does renal failure have on pharmokinetics?
there is reduced clearance of drugs because of a reduction inGFR and protein binding is also reduced, so more free drug is available
what affect does renal failure have on pharmacodynamics?
the renal disease alters the actions of drugs on the tissues eg
the BBB becomes more permeable and the brain becomes more sensitive to tranquillisers, sedatives and opiates,
circulatory volume may be reduced making the patient more sensitive to antihypertensives agents,
increased tendency to bleed, beware warfarin or NSAIDs
why can’t people with reanl failure and hypertension, take normal hypertesnion medication?
because they have a low GFR, they are more senstive to hypotensive actions, so use ACEIs (which are metabolised by the liver), and use reduced doses
what are the 4 major syndromes causes by drug induced renal disease?
acute renal failure, nephrotic syndrome, renal tubular dysfunction with potassium wasting, chronic renal failure
what is acute renal failure?
sudden deterioration in renal function which results in a rapid rise in creatinine
Drugs that cause pre-renal drug induced renal disease?
Diuretics, laxatives, lithium, NSAIDs (they cause water and electrolyte abnormalities),
Steroids, tertracyclines (increase catabolism),
oestrogens/OCP (cause vascular occlusion)
what are the 3 types of intrinsic acute renal failure?
acute tubular necrosis, acute interstitial nephritis, thrombotic microangiopathy
Drugs that cause acute tubular necrosis?
aminoglycoside antibiotics, amphotericin B, cisplatin, radiocontrast agents stains + immunosuppressive drugs
How long does it take for a drug to cause acute interstitial nephritis?
first exposure- up to several weeks,
secondary exposure- 3-5 days
short as 1 day with rifampicin or as long as 18 months with an NSAID
Drugs that can cause acute interstitial nephritis?
penicillins, cephalosporins, cocaine, sulfonamides, NSAIDs, diuretics, lithium, ranitidine, omeprazole, captopril, lithium, phenytoin, valproic acid, amphotericin B, streptokinase, 5-aminosalicylates, allopurinol, rifampin, chinease herbs
what is the pathologic hallmark of thrombotic microangiopathy?
thrombi in the microvasculature of many organs
Drugs that can cause thrombotic microangiopathy?
cyclosporin, tacrolimus, chemotherapeutic agetns, ticlopidine, clopidogrel, 19 estrogen containing oral contraceptives, quinine, cocaine
where can drug associated obstruction of urine outflow occur?
within and outside the ureters and tubules.
Within due to crystal formation,
and outside due to retroperitoneal fibrosis
