Core Concepts in Pharmacology Flashcards
(24 cards)
What are the 4 main processes in Pharmacokinetics?
Absorption, Distribution, Metabolism, and Elimination
What are the pros and cons of administering drugs orally?
Pros: Much more comfortable and easy to administer
Cons: Highly complex with many pathways to go through (Liver)
What are the pros and cons of administering drugs via IV?
Pros: Fastest and most complete drug absorption. Great option in emergencies. Better control and allows drugs to go straight into bloodstream
Cons: Creates a risk of infection due to broken skin
What are the three routes of drug administration and give brief description
Topical: Direct administration of medicine to site
Entero: Through GI tract to site for medication.
Parenteral: Any route not enteral. Ex. IV, Subcut, IM, Transderm, etc.
What are the factors affecting drug administration?
Route of administration, Drug properties & formulation, Drug dosage, and blood flow at administration
What is a loading dose and why is it important?
A loading dose refers to the process of taking a higher than normal dose on the first day of a drug treatment. This is done to build up the concentration of blood in the body. Higher drug conc = Faster rate of absorption
What areas of the body have a faster absorption and why?
Vascularized areas. This is due to the high amounts of blood flowing by these areas
What areas of the body have a slower absorption rate and why?
Areas with fat. Lack of a good blood supply
What are P-Gp, where are they located and what do they do?
Intestinal P-Glycoproteins. They are involved in creating healthy barriers between organs. They are present in the mucosal lining of certain organs. They survey for toxic chemicals and can prevent certain drugs from being absorbed.
Why must drugs administered orally be both hydrophilic and lipophilic?
Drugs are stored in an excipient. This is to give the drug mass/bulk to allow handling. For the drug to have its effects this excipient must first be dissolved in stomach/intestinal fluids which are mostly made up of water (Hydrophilic) before they can be absorbed into circulation. To get into circulation they must pass through a lipid rich plasma membrane (Lipophilic)
A drug needs to be hydrophilic to be dissolved however extremely lipophilic drugs (Highly non-polar) can also be dissolved, why?
Extremely lipophilic can dissolved but its much harder. To allow/speed up this process the patient should eat a healthy fatty diet. This will cause to liver/gallbladder to release bile allowing for the drug to be broken down
How is it possible for an extremely hydrophilic (Highly polar) drug to be absorbed?
The drug will be administered intravenously (Directly into the bloodstream). Allows to drug to bypass the extremely fatty biological membrane
How does the excipient of a drug affect its rate of dissolution?
If a drug has a loose bind to its excipient it will instantly dissolve in the stomach, causes the drug to be fast-acting. However if the drug has a strong bind to its excipient it will take longer to dissolve allowing to dissolve, slow acting drug.
Name the two processes of drug absorption
Passive Diffusion
Carrier Mediated Transport
Define passive diffusion in relation to drug absorption
A drug that is very small and non-polar (Lipid soluble) can pass through biological membrane via diffusion. This movement is dictated by the concentration gradient
Define carrier-mediated transport in relation to drug absorption
Drugs that are large in molecular size or polar (Water soluble) nust be actively transported through the biological membranes. This process often requires energy (ATP)
Should a weakly acidic drug be taken on an empty or full stomach and why?
Empty stomach. pH is much lower, therefore high level of protons present allowing for better absorption
In what forms do weakly ACIDIC drugs exist in (a) the stomach and (b) the intestines. Also where are they primarily absorbed?
Exist in a non-polar, non-ionized form in the stomach
Exist in a polar, ionized form in the intestines
Absorbed in the stomach
In what forms do weakly BASIC drugs exist in (a) the stomach and (b) the intestines. Also where are they primarily absorbed?
Exist in a polar, ionized form in the stomach
Exist in a non-polar, non-ionized form in the intestines
Absorbed in the intestines
Explain the first-pass effect
Oral medication needs to travel through hepatic portal system where it is metabolized losing a portion of its efficacy. Therefore no drug taken orally has a 100% effect
Explain a possible way to avoid the first-pass effect
By administering the drug rectally it could bypass the first-pass effect however if the drug is administered too deep it could go directly into the hepatic portal vein.
Administering the drug via IV guarantees the drug goes straight into the bloodstream and avoids the first-pass effect
List three possible consequences of drug metabolism
1) Large amounts of drugs will be metabolized in the liver, therefore stopping the drug effects
2) Even after a drug is metabolized it may still have an effect
3) The actual drug won’t do anything but its metabolites have an effect. If a person doesn’t have the enzymes the drug won’t have an effect
What are Phase 1 Reactions of Drug metabolism?
Convert non-polar molecules into polar molecules
Can increase, decrease or have no effect on a drug’s biological activity.
Involves the process of oxidation, hydrolysis or reduction
What are Phase 2 Reactions of Drug metabolism?
Conjugate a drug with a very water-soluble compound to form a highly water soluble metabolite
The conjugated drug is typically inactivated and is readily excreted by the kidney
