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Pharmacology ch 1
Principles of pharmacology. ch 1- neuropharmacology by meyer
| Question | Answer |
|---|---|
| What are the five pharmacokinetic factors determining drug action? | routes of administration, absorption and distribution, binding, inactivation, excretion |
| What is bio availability? | The amount of a drug in the blood that is free to bind at specific target sites |
| True or false - drugs often act where they initially contact the body. | False. a drug rarely acts where it initially contacts the body. See absorption and distribution. |
| The active target site that drug molecules bind to are called | Receptors |
| Are drugs active or inactive during depot binding? | Inactive. The molecules may bind to plasma proteins or may be stored temporarily in bone or fat, where it is inactive. |
| What does biotransformation occur as a result of? | metabolic processes in the liver |
| What does inactivation influence? | Both intensity and duration of drug effects |
| What is any amount of a drug in the dependent on? | A balance between absorption and inactivation |
| True or false: some drugs are excreted in an unaltered form. | True. |
| How are liver metabolites from the body eliminated? | Through urine or feces |
| What factors influence drug effects in addition to bioavailability? | How rapidly the drug reaches its target, frequency and history, and nonspecific factors |
| What are nonspecific drug effects | Unique characteristics of the individual that contribute to the effect of a drug. An individuals background, mood, expectations, perceptions and attitude may effect the outcome of drug use. |
| True or false - nonspecific drug effects are based on the chemical activity of a drug receptor site | False. Non specific drug effects are not based on the chemical activity of a drug-receptor interaction |
| What are specific drug effects based on? | The physical and biochemical interactions of a drug with a target site in living tissue |
| True or false - therapeutic effects and side effects can change depending on the desired outcome. | True |
| Why do drugs have a variety of effects? | Because drugs act at a variety of target sites |
| Therapeutic effects | desired physical or behavioral changes associated with a particular drug |
| Side effects | Undesired (or unintended) physical or behavioral change associated with a particular drug |
| Drug action | the specific molecular changes produced by a drug when it binds to a particular target site or receptor |
| Drug effects | Alterations in physiological or psychological functions associated with a specific drug. |
| True or false: the site of drug action may be very different from the site of the drug effect. | True. Consider application of morphine vs. atrophine to the eye (pg. 4, under "the science of drug action") |
| Neuropharmacology | the study of drug-induced changes in the functioning of the nervous system |
| Psychopharmacology | an area of pharmacology concerned with drug-induced changes in mood, thinking and behavior |
| Neuropsychopharmacology | Area of pharmacology focusing on chemical substances that interact with the nervous system to alter behavior, emotions, and cognition. |
| pharmacology | the scientific study of the actions of drugs and their effects on living organisms |
| Why is the placebo essential to the design of experiments? | It is used to evaluate the effectiveness of new medications by eliminating the influence of expectation on the part of the patient |
| Why are double blind experiments desirable? | It ensures that the results of any given treatment will not be colored by overt or covert prejudices on part of either the patient or the observer |
| True or false: when drugs enter the system, the effect every part of the body. | False. When a drug is absorbed to the blood, it does circulate to all cells in the body. However, changes are only induced after the drug binds to specific receptors, which are only found in some places. |
| What is the most popular route for taking drugs, and why? | Oral administration, because it is safe, self-administered, economical, and avoids the complications and discomfort of injection methods. |
| What is required of drugs that are taken orally? | They must dissolvei n the stomach fluids and pass through the stomach wall to reach blood capillaries. They must also be resistant to destruction by stomach acid. |
| What must oral drugs be resistant to? | Destruction by stomach acid. Example - insulin. |
| What is absorption? | Movement of the drug from the site of administration to the blood circulation |
| True or false: a majority of drugs are absorbed in the stomach | False. The majority of drugs are not fully absorbed until they reach the small intestine. |
| What influences the rate of absorption? | The amount of food in the stomach, physical activity |
| What is the first-pass effect | Liver metabolism of some of the drug molecules reduce the amount of available drug before it reaches the general circulation |
| Why does oral administration produce irregular and unpredictable drug plasma levels? | First-pass effect |
| What is the most rapid and accurate method of drug administration? | Intravenous (IV). The precise quantiy of the agent is placed directly into the blood, and the passage through cell membranes is eliminated |
| what is the absorption rate for IM? | 10 to 30 minutes. It can be slowed down by combination with another drug that constricts blood vessels. |
| What is the rate of drug absorption dependent on? IM | The rate of blood flow to the muscle |
| True or false - Intraperitoneal (IP) injection is commonly used in humans. | False. However, it is the most common ROA for laboratory animals. |
| What is an IP injection? | an injection of a drug through the abdominal wall into the peritoneal cavity, the space that surrounds the abdominal organs. It produces rapid effects, but not as rapid as IV |
| What is the absorption rate dependent on for SC administration? And how can it be increased? | Blood flow to the site of injection. It can be increased by rubbing the skin to dilate blood vessels in the immediate area. |
| What factors play a role in drug ionization? | differences in pH and the characteristic of the drug molecule. |
| True or false. Weak acids ionize more readily in an alkaline environment, and less ionized in an acidic environment. | True. |
| Do weak bases ionize more or less readily in an alkaline environment? | Less readily. |
| True or false. The lack of electrical charge makes a drug less lipid soluble. | False. the drug is more lipid soluble and hence readily absorbed from the stomach into the blood. |
| what does the pKa of a drug represent? | The pH of the aqueous solution in which that drug would be 50% ionized and 50% non-ionized. |
| True or false: Drugs that are highly charged in both acidic and basic environments cannot be administered orally. | True. These drugs are very poorly absorbed from the gastrointestinal tract and thus cannot be administered orally. Go pg 12 |
| How does the route of administration alter absorption? | 1) determines area of absorbing surface, the # of cell layers between the site of admin and the blood, the amount of drug destroyed by the digestive process, and the extent of binding to food or inert complexes. |
| What other factors influence absorption? | Drug concentration, solubility and ionization |
| What is the single most important factor in determining plasma drug levels? | The rate of passage of the drug through various cell layers between the site of administration and the blood. |
| What are cell membranes made up of? | Phospholipids |
| Which types of drugs move through the cell membranes by passive diffusion? | Drugs with high lipid solubility |
| What is the direction of movement across the membranes? | Always from higher to lower concentrations |
| True or false: The larger the concentration difference on each side of the membrane, the faster the diffusion. | True. This is referred to as the concentration gradient. |
| True or false: most drugs are readily lipid soluble. | False. Most drugs are not readily lipid soluble because they are weak acids or weak bases that can become ionized when dissolved in water. |
| What does the extent of ionization depend on? | The relative acidity/alkalinity of the solution, and an intrinsic property of the molecule |
| Why does the rate at which the stomach empties into the intestine influence absorption? | The small intestine has a much greater surface area and there is a slower movement of material through the intestine compared to the stomach. This provides a much greater opportunity for absorption of all drugs. |
| Why do some medicines suggest that you take the drug before you eat? | So that the drug will be emptied into the intestines faster than it would be with food. |
| True or false. The parts of the body that have the most blood flow will have the highest concentration of drug. | True. High concentrations of drugs will be found in the heart, brain, kidneys and liver. |
| Where is CSF manufactured? | The choroid plexus |
| what is cerebrospinal fluid? | A clear, colorless liquid that fills the subarachnoid space that surrounds the entire bulk of the brain and spinal cord, and also fills the hollow spaces (ventricles) and their interconnecting channels (aqueducts) |
| What is the principal component of the blood-brain barrier? | The morphology of brain capillaries |
| What are typical capillaries made up of? | Endothelial cells that have both intercellular clefts (small gaps) as well as fenestrations (larger openings) and pinocytotic vesicles (evelope and transport larger molecules through the capillary wall) |
| True or false. Fenestrations and pinocytotic vesicles are common in brain blood vessels | False. Fenestrations and pinocytotic vesicles are rate. There are also very tight junctions which keep most molecules from easily passing through |
| what type of cells surround brain capillaries? | astrocytes (a type of glial cell). The close interface of astrocytes with both nerve cells and brain capillaries provide the astrocytes with a unique opportunity to modify neuron function. |
| True or false: the blood brain barrier does not impede lipid-soluble molecules. | True. The BBB is selectively permeable, not impermeable. Although it does reduce diffusion of water-soluble (ionized molecules), it does not impede lipid-soluble molecules |
| What two areas of the brain have direct contact with the blood? | The area postrema and the median eminence |
| Area postrema | This is known as the CTZ, or chemical trgger zone, and the "vommitting center" It is located in the medulla of the brainstem |
| Median eminence | The median eminence of the hypothalamus allows neurohormones made in the HT to move into the blood traveling to the pituitary gland, in order to regulate anterior pituitary hormone secretion |
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