Pharmacology
Welcome to the Pharmacology module! In this module, you can find resources about the drugs that you administer, how they work, when to use them, and how your body reacts! Pharmacology is, unfortunately, a lot of memorization, but if you can get a conceptual understanding of how it works physiologically it will be a lot easier to understand and remember!.
*I recommend watching the videos at 1.5x speed (click on the gear on the lower right → playback speed → 1.5x).
Visit the website RxList to search for any med you can think of and get a bunch of info!
Pharmacokinetics
Before you can dive in and understand drugs, mechanisms, and clinical usages, watch this to get an idea of how drugs are distributed through your body!
Cells and Receptors
Not so fast.... before we can learn about drugs, let's learn some basic cell physiology. Drugs bind to receptors and affect the cells associated with them, so it's important to get an idea of how they work first!
Ligand-receptor interactions (20).
Some Basics
One more stop before we get to the meds. It is important to understand some of the basic terms used in pharmacology and what they mean.
Why do we give meds in the first place? Well, simply put, they make people feel better. A more scientific answer could be that they alter the body’s physiological response to improve symptoms, treat and/or cure disease. Remember, pharmacology is cumulative, so it is important that you don't forget the little details such as the receptor subtypes mentioned before! Here are some definitions that will make understanding pharmacology easier:
Indication - What the med is used for.
Contraindication - When the med should not be given.
Mechanism of Action (MOA) - What the med does physiologically to elicit a response.
Agonist - A ligand that binds a receptor and upregulates its action.
Antagonist - A ligand that binds a receptor but does not activate it (usually a competitive inhibitor, meaning it prevents the binding of ligands that will activate it).
Allosteric Modulator - A ligand that binds a different part of the receptor (not the 'active' binding site) to elicit a structural change.
Side Effect - "An undesired effect that occurs when the medication is administered regardless of the dose" (23). An example is cough with ACE inhibitors.
Adverse Effect - "An undesired occurrence that results from taking a medication correctly... Adverse events require interventions whereas most side effects spontaneously resolve with time" (23). An example is anaphylaxis to penicillin.
**Note: You will likely hear side effect and adverse effect used interchangeably. There is some grey area, as all adverse effects are side effects but not all side effects are adverse.
BLS Drugs
This video explains the BLS drugs and drug administration!
*Note: The EpiPen Jr. is indicated for children 15-30kg (33-66lbs).
Meds Discussed in This Video: Oxygen, EpiPen, Narcan, Albuterol, Aspirin, Nitroglycerin, Acetaminophen, Activated Charcoal.
Med Math :)
It is important to understand how exactly to calculate a dose prior to learning the medications and their doses. Being able to quickly convert will not only save you time, but you will also look cool not having to use a cheat sheet!
Drip Calculation
Don't let drip rates stop you up. Watch this video to learn the math behind IV drips and how to calculate drip rates.
Animated Pharmacology
The following videos cover the 3 broad topics of paramedic pharmacology using animation to bring the mechanisms to life!
Meds Discussed in This Video: Norepinephrine, Epinephrine, Dopamine, Dobutamine, Albuterol, Metoprolol, Atropine, Ipratropium, Pralidoxime, Succinylcholine, Vecuronium.
ANS Drugs
The autonomic nervous system (ANS) is a key regulator of body homeostasis. This video discusses the drugs that act on the ANS and animates the mechanisms behind them.
*CHF was listed as a contraindication for metoprolol in the video. It should be decompensated CFH. Beta-blockers can actually benefit CFH patients clinically. Click here to read about it.
**Why can't you give norepinephrine for anaphylaxis if it's also a non-selective adrenergic agonist? Answer: Anaphylaxis is diffuse vasodilation AND bronchoconstriction. Norepinephrine will treat the hypotension, but not the bronchoconstriction. Epinephrine has a better affinity for ß1 and ß2, therefore the α/ß combo makes it most effective.
***Read Affinity - The NE & E Story for a better description of reflex bradycardia, as what was mentioned in the video was not as well explained.
Affinity - The NE & E Story
(Click the arrow to the right to read the text below!)
In pharmacology, we talk a lot about affinity. What is it? Well, here is the quick and dirty. Receptor binding is like a game of musical chairs. There are ligands (people) and receptors (chairs). When the music stops, everyone has to sit in a chair, but some will not have a chair to sit in because they are all full. A ligand with a higher affinity for a receptor means that it is more likely to get a receptor compared to a ligand with a lower affinity. Therefore, if we talk about them like musical chairs, the higher affinity means the more likely it will get to sit in a chair.
EPI and NOREPI: Though epinephrine and norepinephrine are both non-selective adrenergic agonists, they have different affinities for the alpha and beta receptors. This varies by source, but norepinephrine has been thought to have affinity for α receptors followed by ß1, and epinephrine has more affinity for ß receptors followed by α1. So, if you give either/or, it will bind to the receptors it has more affinity for first. Because of this, norepinephrine has more of an α effect resulting in a greater change in MAP, and epinephrine has more of a ß effect resulting in a greater change in heart rate and bronchodilation! Additionally, even though NE can bind to ß1 receptors, its effect on heart rate will not be much. In fact, it could even decrease the heart rate (reflex bradycardia). Since it has such a potent α1 effect, it increases TPR a lot resulting in more afterload. This will trigger the baroreceptor reflex to slow down the heart to compensate for the increased blood pressure. Given Epi and Norepi are both endogenous to the human body, this makes total sense because why would we have both if they do the exact same thing?
Cardiac Drugs
This video is an animated discussion of the drugs that act on the cardiovascular system that were not already mentioned in ANS drugs. Please excuse the misspelling of "Nitroglycerin" in the video...
*Inferior/Right MI is a contraindication for Nitroglycerin due to the vasodilatory properties' contribution to a reduction in preload. Click here to read about it.
**More Nitro! You can treat pulmonary edema with a combination of Nitro and BiPAP! Dilate the vessels to make more space, and use positive pressure to "force" the fluid back in! Click here to read about it.
Meds Discussed in This Video: Lidocaine, Procainamide, Amiodarone, Adenosine, Diltiazem, Magnesium Sulfate, Furosemide, Aspirin, Nitroglycerin.
Meds Discussed in This Video: Fentanyl, Morphine, Ketamine, Ketorolac, Nitrous Oxide, Etomidate, Diazepam, Midazolam, Lorazepam, Haloperidol, Glucagon, Diphenhydramine, Hydroxocobalamin, Calcium Chloride, Methylprednisolone, Oxytocin, Sodium Bicarbonate, Thiamine, Tranexamic Acid.
Remaining Paramedic Drugs
This video is an animated discussion of the remaining paramedic drugs that were not discussed in the ANS or Cardiac Drugs videos. Benzodiazepines and anesthetics are discussed, click here to see the difference between them!