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Pharma > Sherif Lectures > Flashcards

Sherif Lectures Flashcards

1
Q

What is pharmacology?

A

It is the science that deals with drugs, their nature, pharmacodynamics, pharmacokinetics, therapeutic uses, adverse effects, preparations and administration.

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2
Q

Define drug.

A

It is a chemical substance that alters body functions and can be used for treatment, prevention or diagnosis of disease.

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3
Q

What is pharmacokinetics?

A

They are the studies of the Absorption, Distribution, Metabolism and Excretion of drugs (ADME) and their mathematical relationship.

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4
Q

What is pharmacodynamics?

A

They are the studies of the biological and therapeutic effects of drugs and their mechanism of action.

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5
Q

What does pharmacotherapeutics study?

A

It studies the selection & use of drugs for treatment, prevention or diagnosis of diseases.

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6
Q

List the sources of drugs.

A
  1. Plant: e.g. atropine from leaves of belladonna
  2. Animal: insulin from the pancreas of pigs
  3. Mineral: MgSO4, iodine
  4. Microorganisms: penicillin from the fungus penicillinum
  5. Synthetic: in laboratory e.g. aspirin
  6. Biotechnology: human insulin by genetic engineering.
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7
Q

What are the types of drug nomenclature?

A
  1. Chemical name: N-acetyl p-aminophen
  2. Generic name: Acetaminophen (paracetamol)
  3. Trade name: Panadol- Adol.
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8
Q

What are the advantages of enteral administration?

A

Most convenient, Safe, Economical, Easy.

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9
Q

What are the disadvantages of enteral administration?

A

Not suitable for: Unconscious, Uncooperative, excessive Vomiting or Diarrhea, Emergencies, Irritant drugs, drugs destroyed by gastric acidity, enzymes, 1st pass effect.

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10
Q

What is the advantage of intravenous (IV) administration?

A

Rapid onset, 100% bioavailability.

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11
Q

What are the disadvantages of intravenous (IV) administration?

A

Most dangerous bioavailability, suitable for transmission of diseases e.g. AIDS, emergency and large volume drugs.

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12
Q

What is the definition of absorption of drugs?

A

Absorption is the passage of drug from the site of administration to the systemic circulation.

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13
Q

What are the methods of transport across cell membranes?

A
  1. Passive transport: a. Simple diffusion, b. Aqueous diffusion.
  2. Carrier-mediated transport: a. Facilitated diffusion, b. Active transport.
  3. Endocytosis (pinocytosis).
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14
Q

What factors affect drug absorption?

A
  1. Molecular size
  2. Pharmaceutical preparations
  3. Lipid and water solubility
  4. Ionization.
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15
Q

What is bioavailability?

A

It is the percentage of unchanged drug reaching the systemic circulation after any route and becomes available for biological effect.

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16
Q

What is the first-pass effect?

A

It is the metabolism of some drugs in a single passage through the liver, gut wall or the lungs before reaching the systemic circulation.

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17
Q

What is the definition of distribution of drugs?

A

It is the passage of drug through body compartments which are separated by capillary walls and cell membranes.

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18
Q

What is Volume of Distribution (Vd)?

A

It is the apparent volume of fluid required to accommodate the entire amount of the drug in the body in the same concentration as that present in plasma.

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19
Q

What is the importance of Vd?

A
  1. Estimate of the extent of tissue uptake of drugs.
  2. Useful in cases of drug toxicity.
  3. Can be used to calculate the loading dose.
  4. Can be used to calculate the total amount of drug in the body.
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20
Q

What is the usefulness of dialysis for high Vd drugs?

A

Dialysis is not useful for high Vd drugs (most of the drug is in the tissues).

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21
Q

What is the usefulness of dialysis for low Vd drugs?

A

Dialysis is useful for low Vd drugs (most of the drug is in the blood).

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22
Q

How can Vd be used to calculate the loading dose (LD)?

A

[LD = Vd x Css (Steady State plasma Concentration)]

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23
Q

How can Vd be used to calculate the total amount of drug in the body?

A

[A = Vd x Cp]

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24
Q

What factors affect the distribution of drugs?

A

1) Perfusion: blood flow to the organ affects drug delivery.
2) Diffusion: ability to diffuse across cell membranes is influenced by lipophilicity, ionization, and molecular weight.
3) Binding to plasma proteins.

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25
Q

What is the significance of binding to plasma proteins?

A
  1. Limits tissue penetration & decreases Vd.
  2. Bound drug cannot be eliminated, prolonging t½ and effect.
  3. Hyboalbuminemia increases free drug, changing therapeutic doses to toxic doses.
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26
Q

What are Class I and Class II drugs in relation to albumin binding?

A

Class I drugs have a low dose/capacity ratio leading to a high bound fraction and small free fraction. Class II drugs have a high dose/capacity ratio leading to a high free fraction.

27
Q

What happens when a Class I drug is given with a Class II drug?

A

The Class II drug displaces the Class I drug from albumin, increasing the concentration of free Class I drug in plasma, leading to increased therapeutic and toxic effects.

28
Q

How do drugs pass across the blood-brain barrier (BBB)?

A

Lipid-soluble drugs pass freely; 3ry amines can pass, while 4ry NH4+ compounds cannot.

29
Q

What are the effects of drugs crossing the placental barrier?

A

Many drugs can harm the fetus, e.g., teratogenic effects from drugs given during the 3rd to 10th week of pregnancy.

30
Q

What is biotransformation (metabolism)?

A

The chemical changes that occur to drugs after absorption until excretion, mainly occurring in the liver.

31
Q

What are the two types of biotransformation reactions?

A

Phase I (Non-Synthetic) and Phase II (Synthetic).

32
Q

What are the consequences of Phase I reactions?

A
  1. Active drugs → inactive drugs.
  2. Inactive drugs → active drugs.
  3. Active drug → another active one.
  4. Active drug → toxic metabolite.
33
Q

What is the most important Phase I reaction?

A

Oxidation by the cytochrome P450 enzyme system.

34
Q

What is the most common Phase II reaction?

A

Glucuronide conjugation.

35
Q

What factors affect biotransformation?

A
  1. Drugs (enzyme induction & inhibition).
  2. Pathological factors.
  3. Pharmacogenetic variations.
  4. Hepatic blood flow.
  5. Age.
  6. Sex.
  7. Drug properties.
  8. Drug dosage.
36
Q

What is the most important route of drug excretion?

A

The kidney.

37
Q

What are the three processes of kidney excretion?

A
  1. Glomerular filtration.
  2. Active tubular secretion.
  3. Active tubular reabsorption.
38
Q

What affects glomerular filtration?

A

Glomerular filtration rate (GFR) and plasma protein binding.

39
Q

What is the action of penicillin?

A

Frusemide decreases tubular secretion of uric acid, leading to hyperuricemia as an adverse effect.

40
Q

What is the basic carrier for certain drugs?

A

Digoxin and quinidine are examples of drugs that use a basic carrier.

41
Q

What affects the excretion of drugs?

A

Changes in urinary pH affect drug excretion.

42
Q

What is the effect of alkalinization of urine?

A

Increases renal excretion of weak acid drugs like Aspirin and Barbiturates.

43
Q

What is the effect of acidification of urine?

A

Increases renal excretion of weak base drugs like amphetamine and ephedrine.

44
Q

What is the effect of Morphine in saliva?

A

Morphine can cause a metallic taste.

45
Q

What happens in acute morphine toxicity?

A

A gastric wash is performed despite Morphine being administered by IV route.

46
Q

How are drugs excreted in bile?

A

In active or conjugated form, they enter the intestine and can be excreted in stool as conjugated metabolites.

47
Q

What is the significance of systemic clearance (Cls)?

A

It is the volume of fluid cleared of the drug per unit time and is equal to the sum of individual organ clearances.

48
Q

What factors affect drug clearance?

A

Blood flow to the clearing organ, binding of the drug to plasma proteins, and activity of drug removal processes.

49
Q

What is plasma (elimination) half-life (t½)?

A

It is the time required to eliminate 50% of a drug from plasma.

50
Q

What determines the dosage interval?

A

The elimination half-life (t½) determines the dosage interval.

51
Q

What is the rule of 5 regarding steady state concentration (Css)?

A

Css is reached after 5 t½; if the dose changes, the new Css is reached after 5 t½.

52
Q

What is a loading dose (LD)?

A

The dose given at the onset of therapy to achieve a rapid increase in plasma drug concentration.

53
Q

What is the formula for loading dose (LD)?

A

LDIV = Vd X Css (target CP); LDOral = LDIV / F (fraction of oral bioavailability).

54
Q

What is a maintenance dose (MD)?

A

The dose needed to keep the plasma drug concentration constant at Css.

55
Q

What is the formula for maintenance dose (MD)?

A

MDIV = CLs X Css X Tm; MDOral = CLs X Css X Tm / F.

56
Q

What characterizes first order kinetics?

A

A constant fraction of drug is eliminated per unit time, with a constant t½.

57
Q

What characterizes zero order kinetics?

A

A constant amount of drug is eliminated per unit time, with a non-linear elimination kinetics.

58
Q

What are the types of drug action?

A

Local or topical action, systemic or general action, and reflex or remote action.

59
Q

What are receptor-mediated mechanisms?

A

Receptors are specific cellular macromolecules that interact with ligands to produce a response.

60
Q

What are ligand-gated ion channels?

A

Receptors that open ion-selective channels in the plasma membrane upon agonist binding.

61
Q

What are G protein-coupled receptors?

A

Receptors that consist of 7 transmembrane subunits linked to G proteins, involved in slow neurotransmitter signaling.

62
Q

What are receptors linked to tyrosine kinase (RTKs)?

A

Receptors formed of an extracellular domain for agonist binding and an intracellular tyrosine kinase enzyme.

63
Q

What are intracellular (DNA-linked) receptors?

A

Receptors that modify transcription of nearby genes upon ligand binding.

64
Q

What are nitric oxide (NO) receptors?

A

Protein receptors inside the cell that activate guanylyl cyclase enzyme upon binding.

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