PPT Flashcards
what is ambulatory BP?
measures BP throughout day and night
after ambulatory blood pressure monitoring (ABPM) a patient may be described as normotensive, what does this mean?
ABPM daytime average below 135/85mmHg
after ambulatory blood pressure monitoring (ABPM) a patient may be described as stage 1 hypertensive, what does this mean?
ABPM daytime average 135/85 or higher
after ambulatory blood pressure monitoring (ABPM) a patient may be described as stage 2 hypertensive what does this mean?
ABPM daytime average above 150/95
a patient after having ABPM is shown to have readings at day and night of less than 10% difference, what does this suggest?
blood pressure would normally dip at night
could be an underlying cause such as sleep apnoea for why this is happening
after having ABPM a patient is found to have a daytime average below 135/85 yet a clinical blood pressure persistently over 140/90. what does this suggest?
white coat hypertension
a patient is 75 and has ABPM of 140/90. when should antihypertensive drug treatment be given?
the patient is under 80 with stage 1 hypertension. these patients should be given treatment if they have any of the following:
- target organ damage
- established CVD
- renal disease
- diabetes mellitus
- 10 yr CV risk 20% or higher
a patient is found to have hypertension, what assessment should be offered?
- albumin:creatinine ratio
- test for haematuria using a reagent strip
- plasma glucose
- electrolytes and creatinine
- estimated glomerular filtration rate
- serum total cholesterol and HDL cholesterol
- examine the fundi for the presence of hypertensive retinopathy
- 12-lead electrocardiograph
what drugs are used in the treatment of hypertension (8)?
- ACE Inhibitors
- Angiotensin receptor blockers
- Beta blockers
- Calcium channel blockers
- Thiazide-like/thiazide diuretics
- Spironolactone (aldosterone antagonist)
- Alpha-receptor blockers
- Loop diuretics
describe the step approach of hypertension treatment and what are the exceptions to this?
- ACE inhibitor/ARB
- calcium channel blocker
- thiazide diuretic
- spironolactone
except in patients older than 55 or of afro-caribean origin
how long should you wait before evaluating the therapeutic effect of hypertension treatment and what BP should be aimed for?
1 month
<140/90 in clinic
<135/85 at home
what is a typical drug and dose given in the inital treatment of hypertension in a white patient under 50?
ramipril 2.5mg oral daily
what would be the first step of hypertension treatment in a patient over 55 or of afro-caribbean origin?
calcium channel blocker
what are the potential side effects of ACE inhibitors?
- dry cough (bradykinins)
- hypotension (usually on first dose)
- angioedema (sporadic and unpredictable)
when are the use of ACE inhibitors cautioned?
patients with renal disease
what are the potential drug interactions of ACE inhibitors?
- with spironolactone-hyperkalaemia
- with NSAID-AKI in patients with renal disease due to reduced perfusion
are there any sick day rules for antihypertensives?
yes
don’t take if unwell due to dehydration
describe cholesterol management in primary prevention of CVD?
QRISK >10%
atorvastatin 20mg
What class of drugs are statins?
HMG-CoA reductase inhibitor
describe the main pathway of lipoprotein formation and metabolism?
- lipids and fatty acids in gut emulsified by bile acids
- transported in chylomicrons to liver
- circulated as cholesterol and triglycerides to tisses in VLDL
- endothelial LPL liberates FFA in adipose and muscle for storage or metabolism
- this LDL is returned to hepatocytes via LDL receptors or taken up by LDL receptors in extrahepatic tissues
- here they are oxidised and contribute to atherogenesis
- HDL pool comes from chylomicrons following action of LPL and the reverse cholesterol pathway returns HDL to liver via receptors
when should patients on statins take it?
simvastatin and pravastatin-short half life-taken before bed to maximise effect as HMG-CoA reductase more active at night
atorvastatin and rosuvastatin-longer half life so can be taken when convenient
what is the mechanism of action of statins?
- inhibit HMG-CoA reductase
- reduces intracellular cholesterol
- activates a protease
- this cleaves sterol regulatory element binding protein (SREBPs) from ER
- these translocate to nucleus and upregulate expression of LDL receptor gene
- increases receptor mediated endocytosis of LDL and lowers serum LDL
- HMG-CoA reductase also reduces intracellular levels of isoprenoids which are intermediates of cholesterol biosynthesis
what are the most common side effects of statins?
-headache
-GI disturbances
-muscle-aches, myopathy, rhabdomyolysis
rise in liver enzymes
in what patients should statins be used in with caution?
- hepatic impairment
- excreted by kidneys so dose should be reduced in patients with renal impairment
- avoided in pregnancy (stop if trying to conceive)
- avoid if breastfeeding
what drugs can reduce the metabolism of statins?
cytochrome P450 inhibitors such as -amiodarone -diltiazem -itraconazole -macrolide antibiotics -protease inhibitors accumulation of statin in body-increased risk of adverse effects
what is the maximum dose of simvastatin when given with amlodipine?
20mg
a patient on statins is started on clarithromycin, what action should be taken?
statin discontinued temporarily until the antibiotic is finished
what is the most common concern for drug interaction between statins and another drug and when is this risk increased?
induced muscle injury
increased for statins metabolised by cytochrome P450 3A4 (simvastatin and atorvastatin)
what statins are preferred if the patient is unavoidably on another strong inhibitor of CYP3A4?
fluvastatin
rosuvastatin
what compund is in grapefruit juice that is a potent inhibitor of cytochrome P4503A4?
furanocoumarins
when prescribing drugs to a patient what do you need to explain to them?
- side effects
- cautions
- interactions
- how to take the drug
- when to seek advice
- sick day rules
when prescribing statins would do you need to explain to the patient?
- seek advice if muscle symptoms
- blood tests in 3 and 12 months
- alcohol to a minimum
- avoid grapefruit juice
- sick day rules don’t apply to statin use
what other drugs can be used to treat high cholesterol?
fibrates
specific cholesterol absorption inhibitors
what is the Well’s criteria?
score of 3 or more suggests DVT
- if high probability of PE=CT
- if low probability of PE=D-dimer
what drugs can be used for immediate anticoagulation?
- unfractionated heparin
- LMWH
- direct inhibitors of factor Xa
how do unfractionated heparin, LMWH and fondaparinux have their anticoagulant affect?
fondaparinux bind to antithrombin via a pentasaccharide sequence and accelerate its inhibition of various coagulation proteases, primarily inhibition of Factor Xa.
what is fondaparinux?
synthetic analogue of the naturally occurring pentasaccharide sequence found in heparin molecules.
what other coagulation effect do heparin molecules with a molecular weight over 5400 have?
bridging antithrombin and thrombin and acting as a catalytic template.
Most heparin chains in UFH are long enough to exert this effect, but at least 50% of the heparin chains in LMWH are too small, hence LWMH exert most of their anticoagulant effect via indirect inhibition of factor Xa
what affect does fondaprinux have on antithrombin?
no effect
dosage of LMWH is dependent on…
- condition used to treat
- body weight
what heparins are usually administered by infusion pump?
unfractionated hepatin
what heparins are usually administered by SC injection?
LMWH
fondaparinux
what monitoring is needed in a patient of heparin and fondaparinux?
none
- what is the potential side effect of heparins?
2. what drugs should be stopped when taking heparin?
- bleeding
2. stop NSAIDs
give examples of direct acting oral anticoaglants (DOACs)?
dabigatran
apixaban
rivaroxaban
what are the vitamin K dependent coagulation factors?
II (prothrombin)
VII
IX
X
what is the mechanism of vitamin K antagonists?
-blocks function of vit K epoxide reductase complex in the liver so less reduced vit K that is a cofactor for gamma carboxylation of vit K dependent coagulation factors
what is epoxide reductase needed for?
recycle vit K between reduced and epoxide forms
what happens to vitamin K dependent factors without gamma carboxylation?
the vitamin K-dependent factors, including factors II (prothrombin), VII, IX, and X, are immunologically detectable, but they cannot function because they cannot adequately bind calcium and phospholipid membranes needed for their haemostatic function
describe Gamma carboxylation of glutamic acid residues and how does this affect desired anticoagulant effects of vit K antagonists?
occurs at the time of protein synthesis; it does not affect the structure or function of existing proteins. Thus, the ultimate anticoagulant effect of VKAs is delayed until the previously synthesized, functional clotting factors are cleared from the circulation. Depletion of both factor X and factor II (prothrombin) is important for clinical efficacy, and factor II has the longest half-life of the vitamin K-dependent factors (approximately three days). Thus, the desired anticoagulant effect of a VKA does not occur for at least three days after drug initiation despite prolongation of the prothrombin time (PT) at earlier time points.
why does warfarin have a transient procoagulant effect during the first day or 2 of use?
VKAs also inhibit vitamin K-dependent gamma carboxylation of the anticoagulant factors protein S and protein C, which inhibit activated factors VIII and V. Thus,warfarinhas a transient procoagulant effect during the first day or two of use. This is rarely of clinical significance, with the possible exception of patients who receive “loading doses” of warfarin (especially those with inherited protein C deficiency) who may (rarely) develop warfarin-induced skin necrosis
what should you do initially when prescribing warfarin?
continue a LMWH for at least 5 days
Warfarin does not have an effect on the function of biologically-active, circulating factors that have already been synthesised – only the inhibition of new factors.
In addition to inhibiting the formation of procoagulant factors 2, 7, 9, 10 – warfarin also inhibits formation of anticoagulant proteins C & S. All the factors have varying half-lives which also carries a risk of warfarin potentially exerting an initial pro-coagulant effect if the presence of circulating anticoagulant factors are depleted prior to procoagulant factors.
why should aspirin be avoided in patients on warfarin?
potential for GI bleed which could be dangerous on warfarin
what mechanisms can medications interact with vitamin K antagonists?
prolonged prothrombin time
increased bleeding risk independent of PT/INR
reduced anticoagulation
describe how medications can interact with VKAs by prolonging prothrombin time (PT)/INR?
- Altered intestinal flora, with reduced intestinalvitamin Ksynthesis
- Inhibition of hepatic CYP2C9, with reduced warfarin metabolism
- Displacement ofwarfarinfrom albumin
describe how medications can interact with VKAs by increasing bleeding risk independent of PT/INR?
- Injury to gastrointestinal mucosa
- Interference with platelet function
- Other (incompletely characterized)
describe how medications can interact with VKAs by reducing anticoagulation?
- Induction hepatic CYP2C9, with increased warfarinmetabolism
- Bypasswarfarineffect via large amounts ofvitamin K
- Incompletely characterized
what drugs interact with warfarin by altering intestinal flora, with reducing intestinalvitamin Ksynthesis?
Antibiotics, especially cotrimoxazole, metronidazole, macrolides and fluoroquinolones
what drugs interact with warfarin by Inhibition of hepatic CYP2C9, with reducedwarfarinmetabolism?
Many agents (e.g. fluconazole, metronidazole, amiodarone, gemfibrozil and sulfamethoxazole
what drugs interact with warfarin by Displacement ofwarfarinfrom albumin?
Any medication that binds albumin; however, this effect is usually minor
what drugs interact with warfarin by injuring GI mucosa?
Aspirinand nonsteroidal anti-inflammatory drugs (NSAIDs)
what drugs interact with warfarin by interference with platelet function?
Anti-platelet drugs, includingaspirin
what drugs interact with warfarin by Induction hepatic CYP2C9, with increasedwarfarin metabolism?
Rifampin,carbamazepine,phenytoin,primidone
what drugs interact with warfarin by bypasswarfarineffect via large amounts ofvitamin K
Some vitamin and calcium supplements
how can the efficacy of warfarin be monitored clinically?
reducedsymptomsof breathlessness in heart failure, or improvedblood pressurecontrol in hypertension
how can safety of warfarin be tested?
checkelectrolytesandrenal functionbefore starting treatment. Repeat these 1–2 weeks into treatment and after increasing the dose. Biochemical changes can be tolerated provided they are within certain limits: the creatinine concentration should not rise by more than 30%, the eGFR should not fall by more than 25%, and the potassium concentration should not rise above 6.0 mmol/L. If any of these limits are exceeded, you should stop the drug and seek expert advice.
in what instance is the therapeutic index INR level higher than nornal?
patients with arteficial heart valves
what is the usual therapeutic level INR levels?
2-3
If the INR is too low or too high what are the consequences?
too low-thromboembolic
too high-haemorrhagic
what should be explained to a patient before they start taking warfarin?
Potential side effects Cautions-avoid grapefruit, kale, if bleed get medical help Interactions How to take the drug When to seek advice Sick day rules?-medical help
what are the issues with using DOACs?
not as easily reversed as warfarin
give examples of DOACs?
Factor Xa inhibitors:
- Apixaban
- Edoxaban
- Rivaroxaban
Direct thrombin inhibitor:
-Dabigatran
what would you give to reverse warfarin?
Vitamin K1
Prothrombin complex concentrate
(fresh frozen plasma)
what would you give to reverse dabigatran?
Idarucizumab (monoclonal antibody fragment)
What would you give to reverse factor Xa inhibitors?
Andexanet alfa (awaiting approval in UK)
describe the drug therapy used in a patient with acute coronary syndrome
Aspirin
Clopidogrel / Ticagrelor
Fondaparinux (or LMWH)
Avoid O2 unless O2 sats < 90% (cause reflex constriction of coronary arteries)
-Avoid IV morphine unless pain unacceptable (10mg in 10mL titrate slow)
-Beta-blocker (improves prognosis)
-Statin (secondary prevention)
give examples of classes of antiplatelet drugs?
- cyclo-oxygenase inhibitors
- phosphodiesterase inhibitors
- adenosine diphosphate receptor antagonists
- glycoprotein IIb/IIIa receptor antagonists
give an example of a cyclo-oxygenase inhibitor?
aspirin (inhibits generation of thromboxane A2(TXA2) by COX-1 which otherwise causes platelet aggregatoin and upregulation of GPIIb and IIIa)
give an example of a phosphodiesterase inhibitor?
dipyridamole (inhibit activation of platelets and downregulate glycoprotein receptors by increasing cAMP)
give examples of adenosine diphosphate receptor antagonists?
clopidogrel
tricagrelor
(inhibit ADP (P2Y12) receptors and prevent ADP induced upregulation of glycoprotein GPIIb/IIIa)
give examples of glycoprotein IIb/IIIa receptor antagonists?
abciximab (antibody)
tirofiban (non-peptide inhibitor)
what dose of aspirin is required to have an antithrombotic effect and how?
low doses
75-81mg/day
irreversibly acetyate serine 530 of COX-1 and inhibit platelet aggregation
what doses of aspirin can cause analgesic and antipyretic effects and how?
intermediate doses
650mg-4g/day
inhibit COX-1 and COX-2 blocking PG production
what doses of asprin can result in anti-inflammatory effects for rheumatic disorders and how?
high doses 4-8g/day PG dependent (COX-2 dependent PGE2) and independent factors
in what ways is aspirin toxic at high doses?
tinnitus
gastric intolerance
bronchospasm (potential side effect)
(if a patient has overdosed and has tinnitus you know they have taken a significant dose)
how does high dose aspiring result in GI problems/
it is a non specific blocker of prostaglandin synthesis
PG2 causes GI problems
why should aspirin not be given in children <16 and what it the exception?
greatly increases the risk of Reye’s syndrome (rapidly progressing encephalopathy)
except in Kawasaki disease
what is the mechanism of action of adenosine diphosphate receptor antagonists?
clopidogrel-irreversibly inhibits P2Y12 receptor and ticagrelor binds to a different site on the receptor and causes reversible inhibition
how do the effects of clopidogrel and ticagrelor differ?
- clopidogrel-considerable interindividual variability in the degree of platelet inhibition and slow onset of action (about 5 days for full effect) without a loading dose.
- Ticagrelor- more predictable inhibitor of platelet activation than clopidogrel, and more rapid onset of action.