Textbook Notes (363,063)
Canada (158,170)
Psychology (9,565)
PSYC62H3 (280)
Chapter 3

Chapter 3.docx

6 Pages
Unlock Document

University of Toronto Scarborough
Suzanne Erb

Chapter 3 - Basic Principles of Pharmacology  Psychological effects of a drug dependent on: - individual’s set - indiv’s setting - particular course of drug activation in CNS - drug dosage - frequency of drug dose  drug - chemical that affects one/more biological processes  endogenous substances - chemicals originating/produced within an organism that are used to carry out normal biological functions in the body  exogenous substances - i.e. drugs  pharmacological perspective - a drug is nonfood, nonmechanical substance (usually a chemical substance) that exerts an effect upon a living system  organic phase - chemistry of carbon-based sub like hydrocarbons, immiscible with water - ex: cholesterol, triglycerides (fats with three fatty acid chains), membrane phosphilipid, the nature of phosphilipids allow them to compose nerve cell membranes, importantly lipid bilayer acts as barrier to movement of polar/charged  lipid bilayer does not allow too water-soluble/lipophobic across the membrane  another significant barrier is the BBB - tight junctions between the endothelial cells that compose the outer lining of the blood vessels - significant resistance to drug entry and other brain subs - very particular - subtle changes in chemical structure can yield substantial difference in passage across BBB - ethanol has both aqueous and organic properties, easily passes into the brain - vs. THC that is highly lipid-soluble, passes BBB but unlike ethanol it does NOT rapidly metabolize so depositing itself in adipose tissue for long periods - lower lipid solubility of morphine results in slower onset of analgesia and less intensity, but LONGER duration than others  pharmacokinetics – movement of drugs within a biological system with respect to drug absorption, distribution, binding, localization in tissues, metabolic alterations and excretion from the body  pharmacodynamics – biochemical and physiological effects of the drugs and their mechanism of action Routes of administration  mouth (per os or PO) is most common, convenient, cheapest, safest way as it is absorbed into GI tract  rectal administration (via rectal mucosa) is an alternative enteral (within the intestine) route for drugs destroyed in stomach, small intestine  many drugs are weak bases/acids and are often ionized (no net electrical charge), to facilitate absorption these drugs need to form salts (compound forming an ionic bond between anion and cations) ; proportion of nonionized to ionized drug molecules present in a given area is important for drug absorption  local pH is another factor influencing drug absorption  intravenous (IV) injection results in rapid onset of drug action and relatively intense effects, can be toxic, fine adjustments are possible, if overdosage does occur then the only solution is an antagonist  repeated injections can lead to clot formation, vessel irritation, vessel collapse, high incidence of allergic rxn, pronounced cardiovascular action and side effects with the IV route  intramuscular (IM) injection results in more rapid absorption than the PO route because of the large blood supply around the muscles  drug inhalation leads to rapid onset of drug action and intense effects, this route eliminates drug loss through first-pass metabolism by the liver, irritants can cause pneumonia and chronic diseases  subcutaneous (SC) drug injection – underneath the skin into the tissue between the skin and muscle (i.e. body fat), the poor blood supply in fatty tissue can be used with nonirritating sub to produce fairly slow and even absorption  sublingual/ buccal administration – through the oral mucosa under the tongue or between the cheek and gum, may be used with drugs that are destroyed in the stomach or intestines, ex. Nitroglycerine, nicotine  intra-arterial administration- rare, generally hazardous because drug is so concentrated  bone marrow administration – in infants, or when veins collapsed  rubbing drugs over skin  intranasal administration – application of drug to the mucous membrane of the nose  intraperitoneal administration – rare in humans, used more in lab animals, inject into abdominal cavity (peritoneum) Drug Delivery Directly into Nervous System  intrathecal administration – injecting drug into subdural spaces of the spinal cord  intracerebroventricular injection – inject into ventricular spaces of the brain, used to bypass BBB and directly hit the nervous tissue  intracranial administration- localized, direct infusion into brain area o controlled drug release systems have been developed, better than sustained-release/slow- release o pro-drugs are also used, the active compound is covalently bound to another chemical structure and is relatively inert when combined with other substituent, but after administration, the active compound is then gradually liberated by spontaneous or enzymatic chemical rxns o transdermal is an alternative as it avoids GI tract degradation and first-pass metabolism, allows steady or time varying controlled delivery, improves patient compliance, due to low skin permeability – few molecules/peptides can surpass barrier BBB  rate of receptor occupancy (faster the drug penetrates BBB), the greater the likelihood of its being abused and producing dependence  unlike endothelial cells of the capillaries elsewhere in the body, the endothelial cells lining the vascular wall of the brain capillaries are tightly linked with junction complexes that eliminate gaps or spaces between cells and prevent any free diffusion of blood-borne substances into the brain extracellular space  brain capillaries have few pores, they are in contact with long extensions of several glial (non- neural) cells known as astrocytes, lipid sheath made up of extensions of “glial feet” from nearby astrocytes surrounds the brain capillaries  for a drug (administered by alternative route that’s not directly into the brain) to have access to the CNS neurons, it must be (a) lipid soluble to some degree or (b) compatible with one of the several carrier-mediated or active transport systems developed in the capillary and astrocyte cells  exceptions to BBB – areas where it is not completely impermeable: 1) capillaries atop the brain stem where the vomiting center is located are permeable to chemicals because the neurons there must monitor blood for foreign toxins 2) BBB temporarily break down result of injury (blow to head/stroke) or illness, allowing chemicals to penetrate it – could be beneficial/harm Dose-Response Relationships  D-R relationship are determined by taking groups of individual subjects (animals/humans) which represent a certain popn, administering different doses of the drug being studied, waiting for a sufficient length of time for the drug to act, and assessing the degree of effect or the number of individuals displaying a specified effect of the drug  Placebo involved, in some cases where humans may be knowledgeable about some characteristics of a drug they are taking, an active placebo is used as it mimics some of the noticeable physiological characteristics of the drug being tested but without the effects on the brain that researcher is interested in  In animals – control condition has vehicle solution – solution that the drug itself is dissolved in  Double-blind procedure – ptpt, researcher doesn’t know if placebo/drug is being used  Efficacy – magnitude of the effect of a drug at the system/organism level, typically expressed as the maximal effect produced by the drug  Intrinsic biological activity or signal transduct
More Less

Related notes for PSYC62H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.