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a concise explanation of pertinent anti-arrhythmic drugs.

Hello and welcome to my lecture on antiarrhythmics in this lecture we’ll discuss drugs by class according to the vaughan williams classification so just to introduce you i still prefer the juan williams classification of drugs this is a classification that groups them by how they work for example class one is sodium channel blockers class two is beta blockers

Class three is potassium channel blockers and class 4 is calcium channel blockers in this lecture we will discuss classes 1 3 and 4 so class 1 drugs olivia sodium tunnel blockers there are 8 relevant drugs in this class in their quantity procainamide die so pyramide lidocaine maxilla teen token i’d flick and id and propafenone and that was really a mouthful it’s

Alphabet soup and the trick is knowing which drug which class there are acronyms out there already but for me sometimes the acronyms are more difficult to remember which kind of defeats the purpose of them so i’ve come up with a couple of my own and i hope they’re useful to you for one c we know one c drugs have very little effect on the effective refractory period

And action potential so we also know that 1c drugs should not be used on damaged myocardium so the drugs in this class are finicky to none or plugin i’d that’s finicky for flecainide and propafenone which has a terminal n o and e so finicky to none for one c drugs for one b we know that it shortens the erp so it puts a lid on the erp because it can for taupey and

I and mcelhatton you can remember because it comes out right after it starts with m which comes right after lidocaine so the drugs in 1b our lidocaine token i and mixology side effects of these drugs now i would encourage you to try and remember side effects of any type of drug in relation to the mechanism of action if you take an example from psychiatry drugs if

Somebody is taking a drug for insomnia a side effect of the drug may very well be somnolence not all the time but most of the time so as you go from subclass a to see just know that the side effects on the heart get worse so when we’re extrapolating the side effects from the mechanism of action for one a since it increases the erp it increases the qt interval and

Can lead to torsades de pointes for one be there kind of the anesthetic class they decrease the erp and that can cause a depressed cardiovascular system one see often time leads to arrhythmias and it can be particularly catastrophic to the av node effective refractory period there are only two major side effects that really important to remember for the drugs in

This class for climbing and quantity and is basically a chin kono mark derivative tinnitus plus headaches plus anticholinergic toxicity and remember that acronym dumbbells for anticholinergic toxicity procainamide can lead to drug-induced s sulli so procainamide is a really big drug on the list of drugs that causes lupus plus three drugs are the potassium channel

Blockers and they are on my o durham a butyl ide to fettle tied and sotalol there are no subclasses in class sorry so class three is a class of last resort i would consider only a butyl i’d just peddle i’d and soda well together and i’ll explain this in a minute but they all increase the action potential effective refractory period and so those three drugs just to

Remember the increase the action potential as well as the effective refractory period but amiodarone is a special one changes a lipid membrane so if retaining a lipid membrane and not just affecting one particular type of channel everything passes through the lipid membrane so since you’re changing it this drug is going to exhibit properties of all the anti rhythmic

Classes and it’s going to prove to be really dangerous so on two side effects of the class three drugs so if we’re struggling for the mechanism of action there increasing the rp increasing the action potential under by they prolong the qt interval so remember when you pull on the key to interval what can you precipitate so back to a be otero and a wonderful since

It alters mit lipid membranes it’s going to be responsible for a whole lot of toxicity it’s like everything but the kitchen sink pulmonary hepato thyrotoxic city it also leads to nerve dysfunction and corneal deposits you should check function tests accordingly so you got your p of t’s l of t is t of t’s and of course it’s going to cause cardiovascular dysfunction

As a side effect class four is a calcium channel blockers they decrease conduction speed and they increase the pr interval the dihydropyridine calcium channel blockers arlen’s class so verapamil and diltiazem the side of extrapolated from the mechanism of action would be the usual calcium channel blocker constipation av nodal block and there’s also a dima that’s

Very common so that’s my presentation on anti-arrhythmic drugs please continue to watch and learn from these videos and also please subscribe to my channel

Transcribed from video
Anti-arrhythmics By MedNStat Reviews for the Boards