cardiovascular DISEASE, RESPIRATORY DISEASE AND THE ORAL CAVITY Flashcards
How is infective endocarditis prevented?
Prophylactic antibiotics. Only given to very particular people (immunocompromised, people with prosthetic heart valves, rheumatic heart disease)
Which cardiac conditions require antibiotic prophylaxis?
Prosthetic cardiac valve, including transcatheter implanted prosthesis or homograft
Prosthetic material used for cardiac valve repair such as annuloplasty rings and chords
Previous Infective endocarditis
Congenital heart disease only if it includes (Unrepaired cyanotic defects, or repaired defects with residual defects at or adjacent to site of prosthetic patch or device)
Rheumatic heart disease (high risk patients)
What should you consider when giving AB prophylaxis?
The risk of giving the antibiotic,
The risk of the patient developing endocarditis from the procedure,
The risk of a potential adverse outcome if the patient does develop endocarditis.
What should be done for patietns with cardiac abnormalities regardless of if AN prophy is indicated?
All patients with cardiac abnormalities should be reminded to practice good oral hygiene and have regular dental check-ups (Minimum 6 monthly)
Refer for investigation of unexplained fever ASAP
What is the difference between pharmacokinetic and pharmacodynamic drug interaction?
Pharmacodynamic interactions are those that modify the pharmacological effect of a drug without altering its concentration in the tissue fluid. This means that the effect of one drug is changed by the presence of another drug at the same molecular site.
Pharmacokinetic interactions are are those that alter the concentration of a drug that reaches its site of action. Therefore, one drug alters the concentration of another drug in the system (either an increase or decrease). This modification could occur at any phase of the drugs life inside you absorption, distribution, metabolism or excretion of the drug
How does aspirin work?
Aspirin inactivates COX enzymes required for thromboxane and prostaglandin synthesis.
Irreversibly inhibits COX1 and modifies enzymatic activity of COX2.
How do NSAIDs and Aspirin interact?
NSAIDs antagonise aspirin (competitive agonist)
Shared binding site on COX-1 on platelet
Patient studies show that >3 days ibuprofen negates cardioprotective effect of aspirin
If you absolutely NEED to give NSAIDs to someone one aspirin what is the best NSAID to give?
Naproxen
What is clopidogrel used for?
It is an antiplateley drug used in primary care. Given to prevent thrombosis after placement of coronary stent.
What are the adverse outcomes of using clopidogrel with NSAIDs?
When a patient takes aspirin or clopidogrel with NSAIDs there is a chance of gastric bleeding proportional to time on NSAIDs.
Unclear whether clopidogrel exerts independent injuries effect on GI mucosa or whether merely induces bleeding in already damaged mucosa (NSAIDs damage mucosa and combined antiplatelet effects)
How can adverse effects of combining clopidogrel, aspirin or NSAIDs be prevented?
PPIs can be prescribed to provide gastric protection.
What interactions besides NSAIDs does clopidogrel have?
Macrolide antibiotics
Azole antifungals
Due to cyp450 inhibition
How does warfarin work?
The mode of action is the inhibition of vitamin K‑dependent clotting factors factors II, VII, IX and X.
What interactions does warfarin have that should be noted?
One potential interaction is with broad spectrum antibiotics where Vitamin K depletion can occur. This depletion ultimately has a detrimental effect on the clotting cascade as without Vitamin K to much Warfarin is biologically active potentially increasing a patient INR.
Metronidazole: This drug comprises over 20% of all drugs prescribed by GDPs and thus there is a relatively high potential for an interaction. There have been several reports of significant bleeding in patients taking warfarin with concomitant use of metronidazole
Macrolide antibiotics: Evidence suggests that increases in INR are detected in patients who were previously stabilised on warfarin, when simultaneously given a macrolide
Azole antifungals: there are now several reports of oral miconazole gel interacting with warfarin in the systemic circulation, confirming that the gel can be absorbed with potentially harmful interactions
NSAIDs and aspirin: Compete with plasma binding proteins leading to more pharmacologically active warfarin causing much higher INR.
How can the interaction of warfarin with ABs be managed?
Monitor INR if AB is taken for >5 days
Avoid in susceptible patients
What theory explains metronidazole’s interaction with warfarin?
Metronidazole’s metabolism and its specific effect on warfarin are not as clearly defined. Metronidazole has been reported to have a stereoselective inhibition of S-warfarin metabolism which suggests possible inhibition of CYP2C9, the enzyme responsible for S-warfarin metabolism.7,8 Inhibition of CYP2C9 by metronidazole would delay metabolism of S-warfarin; this would lead to an enhanced anticoagulant effect and increase the potential for bleeding complications.
What are the clinical recommendations when metronidazole is absolutely unavoidable?
Liaison with the patient’s GMP is essential before any treatment and under no circumstances should the GDP modify the patient’s warfarin medication dosage.
Generally the doctor would reduce warfarin by approximately 1/3rd to 1/2 of current dose
When should INR be taken?
On the day or afternoon before the extraction.
Advise to keep NSAIDs to a minimum and report heavy/continuous bleeding.
What are the types of antihypertensive drugs that can be prescribed?
Diuretics
Calcium Channel Blockers
ACE inhibitors
beta-blockers
Angiotensin II antagonists
How do beta blockers and adrenaline interact?
When nonselective beta blockers are given they block the vasodilation action and the adrenaline given increases vasoconstriction. This leads to unopposed alpha vasoconstriction.
This can lead to hypertensive crisis. This isn’t true for most people but patients with BP above 200/115 should be given minimal anaesthetic.
