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Lecture 1.docx

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PSYC 3403
Tarry Ahuja

Lecture 1 Overview - Drug absorption/administration - Drug distribution - Termination of drug action - Time course of drug distribution (half-life) - Drug tolerance and dependence Pharmacokinetics - In Greek: “pharmacon” means drug and “kinetikos” means putting in motion, the study of time dependency - Pharmacokinetics: • Is the time course of a particular drug’s actions **KNOW THIS FOR MIDTERM**  Absorption  Distribution  Metabolism  Elimination - How much drug is in your blood at any specific time - Cmax= most concentration of, say, aspirin.After, the concentration in the blood decreases - In this diagram, there have been 4 administration of the drug - Lorazepam (24hrs) vs. Triazolam (8hrs) • To help you sleep, Triazolam will be best because we sleep about 8-9 hours a night. You want your pill to last about 8 hours to help you sleep.Anything beyond that would result in prolonged sedation (wake up sleepy, rather than refreshed and non- drowsy) • If you suffer from anxiety, Lorazepam would be best, because anxiety doesn’t just last for a few hours Administration - Enteral • Oral administration (mouth) • Rectal administration (suppository) - Parenteral • Administration by inhalation (lungs) • Administration through mucous membranes (nose/mouth) • Administration through the skin (patch) • Administration by injection (IV, muscle, skin) Administration (oral) - Must be G.I. resistant • Your stomach is very acidic, so the pill needs to be somewhat resistant in order to survive in your stomach’s acid bath for it to help (ex: a coating for protection) • If you need 2mg, and your pill has 10mg, 8mg is broken down while you can still get 2mg - Liquid vs. tablet/capsule • All work the same. Paying for the 5 minute difference • Liquid (~15 minutes) gets into your blood faster than solid (~20 minutes) • Name brand vs. generic  THEYARE THE SAME!! - Passive diffusion • Take the pill and the molecules in your stomach go into your blood • Going from one area of concentration into one of less concentration - Lipid solubility • The more lipid soluble something is, the easier it is to go through fat (more lipid soluble = easier and more entry into the blood) - Disadvantages: • Vomiting, stomach discomfort • Variable levels of absorption • Insult from stomach acids Administration (rectal) - Delivered in suppository - Used in restricted conditions • Ex: if having a seizure or vomiting, cannot give it orally - Disadvantages: • Poor absorption parameters  Environment not designed for this. Lots of blood, but may be harder to get to that blood supply • Rectal membrane irritation Administration (inhalation) - Rapid exchange between lung and blood - Rapid delivery to brain • Gets from lung, to blood, to brain within seconds (ex: first time smoking) - Used for anesthetic gases Administration (mucous membrane) - Administered through nose/mouth - Absorbed through mucosal membrane directly into bloodstream • Very thin membrane - Sublingual administration • Put something right under your tongue - Includes: cocaine, nitroglycerine, nicotine gum, inhalers (puffers) Administration (transdermal patch) (Membrane = barrier) - Provides slow, continuous, controlled release • Avoids the C maxand C minissues - Absorbed through epidermis directly into bloodstream - Nicotine (anti-smoking), fentanyl (chronic pain), estrogen (birth control) Administration (injection) - Intravenous (vein) - Intramuscular (muscle) - Subcutaneous (under skin) - Fast absorption into bloodstream • No hurdles. Right into the blood. The fastest way. - No insult from GI tract - Disadvantages: • Unable to respond to unexpected reaction • Must use sterile techniques (ex: HIV infected needle) • Essentially irreversible (cannot remove if given the wrong needle) Drug distribution **KNOW THIS FOR MIDTERM!** - Only a small portion of the drug is actually interacting with target receptors (side effects) • There are many different receptors. Ex: serotonin has many different types of serotonin • If you activate unwanted receptors, it will cause side effects - Think of drugs like a key and the receptors as the keyhole - Oral: • Through GI tract into portal system (blood supply system) (goes to liver and kidney) • Drug enters central circulation to heart • Drug may be metabolized by GI tract or liver (first-pass metabolism)  That drug in its first path is already getting broken down. Before it even reaches your brain, it gets broken down. • Alcohol dehydrogenas
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