Pharmacology - Block 1 - Part 2
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Pharmacokinetics 6 - Excretion
| Question | Answer |
|---|---|
| This is not affected by lipid solubility of the drug | Glomerular Filtration |
| The size (MW<65000) of the drug, protein binding and renal blood flow affect this | Glomerular Filtration |
| Giving Ammonium chloride or Vitamin C or Cranberry juice will do this to urine | Acidify |
| Giving Sodium bicarbonate or Acetazolamide will do this to urine | Alkalinize |
| Probenecid will compete with this drug in transport systems | Penicillin |
| Probenecid, competes with Uric acid for its reabsorption in renal tubule. Therefore probenecid is useful in the treatment of this condition | Gout |
| The metabolism to convert a drug to an excretable form plus excretion of a drug | Elimination |
Pharmacokinetics 7 - Advanced Pharmacokinetics
| Question | Answer |
|---|---|
| The body may be considered as a single compartment in which the drug is uniformly distributed | Single Compartment Model |
| The body has a central compartment and a peripheral compartment. The drug can distribute from the central compartment to the peripheral compartment and back again | Two Compartment Model |
| Most parameters of a drug can be calculated from this which is determined by administering a dose of drug and then measuring the drug plasma concentration at different times | Plasma Concentration vs Time Curve |
| Maximal drug concentration obtained with a dose | C max |
| Time at which C max is reached | T max |
| Time plasma concentration remains greater than minimum effective concentration (MEC) | Duration of Action |
| The plasma concentration of a drug required to produce a therapeutic effect | Minimum Effective Concentration |
| The range between toxic level and the minimum effective concentration | Therapeutic Range |
| Procedure of measuring and monitoring the drug concentration in plasma at different time intervals is called this | Therapeutic Drug Monitoring |
| Below this range, the drug is not effective and the patient begins having symptoms again. Above this range the drug has bad or toxic side effects that you want to avoid | Therapeutic Range |
| Antiepileptics, Cardiac drugs, Aminoglycosides antibiotics and Lithium require this | Therapeutic Drug Monitoring |
| Question | Answer |
|---|---|
| When a constant fraction (or percentage) of the drug is absorbed, distributed or eliminated per unit time | First Order Kinetics |
| When a constant amount of the drug is absorbed, distributed or eliminated per unit time | Zero Order Kinetics |
| Any drug that is given in extremely, excessively high doses can switch to this kinetics | Zero Order Kinetics |
| Phenyton and aspirin in low to mid therapeutic doses follows this kinetics | First Order Kinetics |
| Phenyton and aspirin in high therapeutic doses follows this kinetics | Zero Order Kinetics |
| All drugs in toxic doses will follow this kinetics | Zero Order Kinetics |
| Alcohol always follows this kinetics regardless of amount | Zero Order Kinetics |
| This drug always follows zero order kinetics regardless of amount | Alcohol |
| Question | Answer |
|---|---|
| The pharmacokinetic parameter that gives a quantitative measure of drug absorption is | Bioavailability |
| The pharmacokinetic parameter that gives a quantitative measure of drug distribution is | Volume of Distribution |
| The pharmacokinetic parameter that gives a quantitative measure of drug elimination is | Clearance |
| Extrapolation of the elimination curve to time zero | C [0] |
| The volume of the plasma (blood) cleared of the drug, in a unit time | Clearance |
| If the drug is reabsorbed by the tubule that drug will have a clearance ____ than the GFR | Less |
| If the drug is secreted by the tubule that drug will have a clearance _____ than the GFR | More |
| If the drug is this, the formula CL=Rate of Elimination/ Plasma Concentration | Not Protein Bound |
| If the drug is this, the formula CL=GFR x free fraction (ff) is used to calculate clearance | Protein Bound |
| If the drug is protein bound, the formula GFR x free fraction (ff) is used to calculate this | Clearance |
| Time required to reduce the plasma concentration of the drug to its half of its original value | Plasma Half-Life |
| The formula 0.693 x Vd / CL is used to calculate this | Plasma Half-Life |
| A drug is considered to be essentially eliminated from the body after this many half-lives | 5 Half-Lives |
| Dose / Concentration (zero time) | Volume of distribution (Vd) |
| This is the desired or optimal plasma concentration required to have the clinical effects of a drug | Target Concentration |
| Clearance (CL) x Plasma Concentration (C[ss]) / Bioavailability (F) | Maintenance Dose |
| Average plasma concentration of the drug is maintained without much fluctuation. This takes place when the rate of drug administration becomes equal to the rate of drug elimination | Steady State Plasma Concentration (Css) |
| The number of half-lives needed to achieve 50% of the steady state plasma concentration | 1 Half-Life |
| The number of half-lives needed to achieve 100% of the steady state plasma concentration | 5 Half-Lives |
| A large dose given initially to get the drug levels up to a target concentration rapidly | Loading Dose |
| Question | Answer |
|---|---|
| 0.693xVd/CL | Half Life |
| D/C | Vd |
| D= Vd x C | Loading Dose |
| CL x Css /F | Maintenance dose (MD) |
| Ko = Cl x Css | Rate of infusion |
| AUC[PO] / AUC[IV] | Bioavailability (F) |
Pharmacodynamics
| Question | Answer |
|---|---|
| The study of drug effects inside the body | Pharmacodynamics |
| Aspirin inhibiting cyclooxygenase which inhibits prostaglandins synthesis is an example fo this type of drug action | Enzyme Action |
| Radioactivity - 131 Iodine and Osmotic activity - Mannitol are examples of this type of drug action | Physical Action |
| Antacids - neutralizes gastric acid and chelating agents - inactivates toxic metals are examples of this type of drug action | Chemical Action |
| The ability of the drug to combine with the receptors | Affinity |
| The ability of the drug to activate and induce a conformational change in the receptor after occupying the receptor | Intrinsic Activity |
| Both affinity and maximal intrinsic activity. The drugs that bind and interact with a receptor, thereby initiate a chemical reaction inside cell and produces effect | Agonist |
| Only the affinity but no intrinsic activity. A drug that binds to the receptor but can not activate it. It blocks the effect of an agonist for that receptor | Antagonist |
| Any drug that binds to a receptor and produces an opposite effect as that of an agonist. Will have affinity and negative intrinsic activity | Inverse Agonist |
| Will have affinity but submaximal intrinsic activity. When given alone the partial agonist activates receptor to produce an effect. However less response than a full agonist. When given along with an agonist, it will block the agonist action. | Partial Agonist |
| Question | Answer |
|---|---|
| The initial combination of drug with the receptor resulting in conformational changes in cell | Drug Action |
| The ultimate change in biological function as a consequence of drug action | Drug Effect |
| A series of intermediate steps between drug action and drug effect | Transducer Mechanism |
| ACh and GABA are examples of this receptor binding | Ligand-Gated Ion Channels Receptors |
| Epinephrine and Histamine are examples of this receptor binding | G-Protein Coupled Receptors |
| Insulin is an example of this receptor binding | Kinase-Linked Receptors |
| Steroids, Vitamin A, D, and Thyroxin are examples of this receptor binding | Intracellular Receptors |
| This is manifested as increased cardiac contractility, relaxation of smooth muscle, lipolysis, glyconeogenesis | cAMP Pathway |
| Contraction of smooth muscle, secretion and transmitter release, neuronal excitability, cell proliferation | IP3-DAG Pathway |
| Stimulates adenylyl cyclase and increases cAMP production and opens Ca2+ channels | Gs Activation |
| Inhibits adenylyl cyclase and decreases cAMP production | Gi Activation |
| Activates phospholipase C | Gq Activation |
| Beta 1, Beta 2, D1, H2 and 5HT-4 receptors use this protein for signal transduction | Gs G-Protein |
| Alpha 2, M2 receptors use this protein for signal transduction | Gi G-Protein |
| M1, M3, Alpha 1 and 5HT-1 use this protein for signal transduction | Gq G-Protein |
| Sigmoid shaped curve that has the dose versus effect | Dose Response Curve |
| On a Dose Response Curve, the height of the curve tells this about the drug | Efficacy of the Drug |
| On a Dose Response Curve, the slope of the curve tells this about the drug | Rate of Action of the Drug |
| The point at which an increase in dose does not produce an increase in effect on a Dose Response Curve | Plateu |
| It refers to the amount of drug needed to produce the response | Potency |
| Dose required to produce half the maximum response is used as an index to determine the potency | ED[50] |
| ED[50] is the index measure of this | Potency |
| Moderate increase in dose leads to more increase in response | Steep DRC |
| Moderate increase in dose leads to little increase in response | Flat DRC |
| Dose required to kill 50% of the subjects | LD[50] |
| Ratio of LD[50] / ED[50] | Therapeutic Index (TI) |
| The dosage range between the minimum effective therapeutic concentration or dose, and the minimum toxic concentration or dose | Therapeutic Window |
| Gap between therapeutic effect DRC and adverse effect DRC defines this | Safety Margin |
| When two drugs are given together or in quick succession nothing happens | Indifferent |
| When two drugs are given together or in quick succession action of one drug is facilitated by the other | Synergism |
| When two drugs are given together or in quick succession action of one drug may decrease or inhibit the action of other drug | Antagonism |
| Increase in the number of receptors on the surface of target cells, making the cells more sensitive to a hormone or another agent | Up Regulation |
| This regulation is generally seen with use of antagonists | Up Regulation |
| Decrease in number of receptors on the surface of target cells, making the cells less sensitive to a hormone or another agent | Down Regulation |
| This regulation is generally seen with prolonged & frequent use of short acting agonists | Down Regulation |
| Gradual reduction in response to drugs and the requirement of higher dose to produce a given response over a period of time | Tolerance |
| Activated Charcoal used in poisoning, which adsorbs the poison material ,later get excreted | Physical Antagonism |
| Chelating agents used in metal poisoning, forms insoluble complexes with metals which can be excreted. Antacids used in acid peptic diseases | Chemical Antagonism |
| Also called as functional antagonism. Two drugs act on different receptors and produce opposite effects on same physiological system | Physiological antagonism |
| Two molecules competing for receptor | Receptor Mediated Antagonism |
| Receptor mediated antagonism that is reversible | Competitive |
| Receptor mediated antagonism that can be reversible or irreversible | Noncompetitive |
| Antagonist reversibly bind to receptors at the same binding site (active site) as the agonist | Competitive Antagonism |
| The antagonist irreversibly covalently binds to the active site of the same receptor changing the receptor conformation | Irreversible Non-Competitive Antagonism |
| The antagonist reversibly binds to an allosteric site of the receptor changing the receptor conformation | Reversible Non-Competitive Antagonism |
| An increase in receptor number is called | Upregulation |
| A decrease in receptor number is called | Downregulation |
| Prolong use of antagonists may lead to | Upregulation |
| Prolong use of agonists may lead to | Downregulation |
| Gradual reduction in response to drugs over time or the requirement of higher dose to produce a given response | Tolerance |
| Rapid desensitization to a drug produced by inoculation with a series of small frequent doses. A rapidly decreasing response to a drug following its initial administration | Tachyphylaxis |
| a maximal response can be elicited at a concentration that does not require the occupancy of all receptors in a cell or tissue | Spare Receptors |
| Spare receptors increase the ________ to a drug | Sensitivity |
| Concentration of the drug required to bind 50% of the receptor sites | K[d] |
| The measure of the affinity of the drug molecule to the receptor | K[d] |
| If EC50 is less than this, spare receptors are said to exist | K[d] |
| If this is less than Kd, spare receptors are said to exist | EC[50] |
| A genetically based, abnormal response to a drug. Most often, they are dose-dependent and they are linked to genetic polymorphism of drug metabolizing enzymes | Idiosyncrasy |
| Prolonged apnea seen with this drug due to plasma cholinesterase deficiency | Succinylcholine |
| Malignant hyperthermia seen with general anesthetics especially this drug | Halothane |
| Only after a previous sensitizing contact with the same drug or with another drug closely related in chemical structure | Crossed Sensitization |
| Drugs ability to cause an abnormal development of the fetus or the appearance of malformations. Morphological damage as well as a functional damage. Both are generally irreversible | Teratogenicity |
| Consumption of alcohol during pregnancy. Consists of CNS dysfunctions (such as low IQ and microencephaly), slowness in growth, a cluster of facial abnormalities, and malformations | Fetal Alcohol Syndrome |
ANS Introduction
| Question | Answer |
|---|---|
| Largely concerned with consciously controlled functions such as movement, respiration, and posture | Somatic division |
| Largely autonomous (independent) in that its activities are not under direct conscious control. It is concerned primarily with visceral functions that are necessary for life - such as cardiac output, blood flow to various organs, digestion | Autonomic Nervous System (ANS) |
| Division of ANS into sympathetic and parasympathetic is determined by this | Location of Ganglion in Spinal Cord |
| Division of ANS originating from the cerval and sacral spinal cord | Parasympathetic |
| Division of ANS originating from the thoracic spinal cord | Sympathetic |
| Acetylcholine is the neurotransmitter | Cholinergic Nerons |
| Adrenaline (Epinephrine ) or noradrenaline is the neurotransmitter | Adrenergic/noradrenergic |
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