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Pharmacology > LO 4 > Flashcards

LO 4 Flashcards

1
Q

What are the 4 dose forms?

A
  1. Solid - tablets, capsules
  2. Liquid - solutions for injections (homogeneous mixture), suspension for injections (precipitates), suspensions for oral administrations, syrups, solutions for rinses
  3. Gels - topical application
  4. Aerosol spray
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2
Q

What are the 2 routes of administration?

A
  1. Enteral - directly in the GI tract; through oral, rectal route
  2. Parenteral - GI bypassed via injection, inhalation, topical administration routes (conversationally in medical spaces, parenteral refers to injections)
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3
Q

What is the onset of a drug?

A

Time it takes for the drug to begin its effect e.g. Tylenol takes about 30 mins - route of admin affects onset

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4
Q

What is the duration of a drug?

A

Length of a drug’s effect e.g. the effect of Tylenol lasts 4-6 hours

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5
Q

What are the advantages of the oral route of administration?

A

Simple, safe, most frequent, inexpensive, accepted easily by patients ,large absorption area(small intestine) and multiple dosage forms: capsules, syrup, tablets

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6
Q

What are the disadvantages of the oral route of administration?

A
  1. Slower onset :first pass effect through liver -this is why onset takes longer
  2. blood levels are less predictable, influenced by food, GI disease, gastric acid, first pass effect, presence of other drugs (drug interactions)
  3. GI irritation, vomiting or nausea
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7
Q

What are the advantages of the rectal route of administration (Suppositories, creams)?

A
  1. Usually local, sometimes systemic effects (anti-emetic)
  2. Good option, if patient is vomiting or nauseated
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8
Q

What are the disadvantages of the rectal route of administration?

A
  1. Poor and irregular absorption
  2. Patient acceptance is poor
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9
Q

What are the advantages of the intravenous route of administration?

A
  1. Most rapid, almost immediate onset=> already in blood stream, no absorption necessary.
  2. More predictable response
  3. Used in emergency situations
  4. Large volumes administered at one time
  5. Constant plasma concentration.
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10
Q

What are the disadvantages of the intravenous route of administration?

A
  1. local irritation( phlebitis)
  2. allergy - difficult to contain allergic reaction to injectable
  3. side effects due to high drug concentration - e.g. hematoma
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11
Q

Describe intramuscular route of drugs

A
  1. Deltoid or gluteal regions
  2. Rapid absorption due to high blood flow through the muscles
  3. Used for vaccines
  4. Useful for injection of suspensions (penicillin G)
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12
Q

Describe the intradermal route

A

Small amounts of drugs are injected just under the skin (TB skin test, allergy tests, local anesthesia)

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13
Q

Describe the Subcutaneous route

A
  1. Drugs are injected in the form of solutions or suspensions into the subcutaneous tissue to gain access to systemic circulation ( insulin)
  2. Small amounts
  3. sterile abscess may result
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14
Q

Describe the inhalation route

A
  1. Drugs in gaseous( nitrous oxide, O2), liquid( puffers), powdered( puffers), volatile liquids (halothane) forms
  2. Used for local (anti asthma medication) and systemic effect (analgesics, anesthetics, nitrous oxide, O2)
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15
Q

Describe the topical route

A
  1. skin, oral mucosa, sublingually
  2. Local (topical anesthetic) or systemic effect ( Nitroglycerine). Rapid onset because avoids first pass effect and GI acids and enzymes.
  3. Systemic side effects => allergy or toxicity)
  4. In the oral cavity, interruptions in the mucous membranes or inflammation increase the likelihood of a systemic effect.

*e.g. Topical anesthetic, Sublingual tablets(Nitroglycerin)

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16
Q

What are the 5 signs of inflammation?

A
  1. Redness
  2. Warmth
  3. Swelling
  4. Pain
  5. Loss of function
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17
Q

Describe Pharmacokinetics

A
  1. “branch of pharmacology that deals with the movement of drugs within the body”
  2. the study of how a drug enters the body, circulates within the body, is changed by the body and leaves the body.
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18
Q

What are the 4 elements of Pharmacokinetics

A
  1. Absorption
  2. Distribution
  3. Metabolism
  4. Excretion of a drug
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19
Q

Describe absorption of a drug

A

The movement of drug molecules from the administration site, through biological membranes, into the bloodstream.

Drugs need to cross:
1. cellular membrane
2. capillary membranes

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20
Q

The degree of absorption depends on ________

A
  1. Cellular factors
  2. Drug factors
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21
Q

Describe cell membranes

A
  1. bilayer of lipids making it semi permeable to ions and polar molecules.
  2. hydrophilic, polarized head on exterior/ lipophilic (AKA hydrophobic) ends on interior
  3. The membrane has also pores of different shapes and sizes => passage of small size, low molecular weight molecules.
  4. Pores are lined with a positive charge=>will allow absorption of a non-ionized molecule.
22
Q

List the Physiochemical properties of drugs and absorption

A
  1. Molecular size
  2. Solubility
  3. Ionization
  4. Dose form
  5. Concentration of the drug on the absorbing surface
23
Q

Describe how Drug molecular size impacts absorption

A

The smaller the drug size, the faster and easier it is absorbed.

24
Q

Describe how Drug solubility impacts absorption

A

The more lipid soluble a drug, the faster it will pass through cell membrane.

25
Q

Describe how Drug ionization impacts absorption

A

pH of the body fluid in which the drug is dissolved

26
Q

Provide an overview of drug ionization

A

Acid drugs (e.g. aspirin):
1. non-ionized in acidic environment (gastric juice)
2. drug absorption is favorable
3. Acid drugs are mainly ionized when in alkaline environment. Absorption is at slower rate, therefore, unfavorable

Basic drugs (e.g. morphine):
1. are mostly non-ionized in alkaline environment(rectal administration) - drug absorption is therefore favorable.
2. Basic drugs are mostly ionized in acidic environment(gastric juice). Absorption is unfavorable.

27
Q

Acidic drugs are NOT ionized in the acidity of the stomach therefore, they are better absorbed if taken _________

A

orally

28
Q

Describe how dose form impacts the absorption of drugs

A

Solutions are absorbed more quickly than solids( capsules, tablets)

29
Q

Describe how the concentration of the drug on the absorbing surface affects absorption

A
  1. If too diluted with food or water=> not adequate contact and less effect
  2. If too concentrated=> irritation to membranes may result, interfering with absorption.
30
Q

Drug absorption is most favorable when __________

A
  1. The molecular size of drug is very small
  2. The drug is lipid soluble
  3. The drug is non-ionized
  4. The drug is dissolved in a solution
  5. The drug concentration is right
31
Q

Describe bioavailability

A
  1. The percentage of the dose of a drug that is absorbed into the general circulation.
  2. GI route => reduced bioavailability (because of first pass metabolism)
  3. IV route => 100% bioavailability (injected directly into the bloodstream).
32
Q

Describe distribution of drugs

A
  1. The movement of drug from the bloodstream into the tissues and fluids of the body.
  2. After a drug is absorbed from its site of administration, it must be distributed to its site of action by the blood plasma.
  3. Potentially reaching all body tissue
33
Q

What are the factors that determine how much drug reaches any organ/tissue?

A
  1. Plasma protein binding
  2. Blood flow
  3. Presence of specific tissue barriers - Blood Brain Barrier and Placental Barrier
34
Q

Describe protein binding on drug distribution

A
  1. Albumin and globulins in plasma form a circulating protein pool.
  2. Their role is to - regulate osmotic pressure; transport hormones, vitamins, drugs.
  3. Drugs are attracted to plasma proteins, especially albumin or can be freely flowing in blood stream
  4. So they can either be - reversibly protein bound (storage site) OR free drug (active drug)
35
Q

Describe blood flow on drug distribution

A
  1. The various organs, receive different amounts of blood.
  2. Liver, kidney, brain : largest blood supply - exposed to the largest drug amounts
  3. The blood-brain barrier decrease drug distribution.
36
Q

Describe impact of specific tissue barriers on drug distribution

A
  1. Blood Brain Barrier and Placental barrier have no pores - Drug must diffuse trans-cellularly
  2. drug must be non- ionized and highly lipid soluble
  3. Only few drugs can cross this barrier (in the 100s)
37
Q

Describe redistribution

A

A drug can move from - site of action (specific site) to nonspecific site (affecting the drug’s duration of action)

38
Q

Describe metabolism (biotransformation)

A
  1. Process that changes the drug to an inactive form that will eventually be eliminated from the body.
  2. Occurs mostly in Liver, via enzymatic processes - Result: metabolite, more water soluble and more ionized
  3. Metabolite is easier to be excreted by the kidney
  4. Metabolite is more difficult to be reabsorbed
  5. Metabolite is more difficult to bind to plasma or tissue proteins
39
Q

Describe First pass effect (First pass metabolism)

A
  1. Drugs absorbed through the mucosa of stomach or intestine will enter into the portal circulation(liver) before reaching the systemic circulation.
  2. The drug will undergo biotransformation, thus reducing the amount of active drug that reaches the general circulation - impact on bioavailability
40
Q

Describe excretion of drugs

A
  1. Renal (urine)
  2. Lungs, Milk, Sweat, Bile (feces).
  3. Enterohepatic circulation can reabsorb and prolong effect of drugs
  4. Saliva: passive diffusion: then ingested and follow the route of oral administration.
  5. Gingival Crevicular Fluid: Tetracycline is 4X more than in plasma
41
Q

Describe renal excretion of drugs

A

Elimination of drugs in the kidney can happen by:
1. glomerular filtration (most drugs); nonselective, free drugs
2. active tubular secretion
3. passive tubular diffusion; non-ionized, lipid-soluble molecules; influenced by pH of urine

*altering urinary pH, drug excretion can be stimulated ( poisoning Tx) or inhibited (to prolong drug effects).

42
Q

Describe Pharmacodynamics

A

The study of:
1. biochemical and physiological effects of drugs
2. mechanisms of drug action
3. relationship between drug concentration and effect
4. is the study of what a drug does to the body

43
Q

What 3 actions can drugs be classified by?

A
  1. Biochemical action - (hypoglycemic agents, SSRI agents)
  2. Physiologic effects - (antihypertensive agents, Ca channel blocker)
  3. Organ/systems - involved (CNS stimulants, vasoconstrictors)
44
Q

Describe the dose-effect relationship

A
  1. Effect of any drug depends on the amount of drug that is given.
  2. The intensity and duration of a drug’s effects are a function of the drug dose and drug concentration at the effect site
  3. Dose-effect relationship is an S curve when plotted on a graph
45
Q

Describe potency

A
  1. Potency: how much of the drug is required to produce an effect.=>dose dependent
  2. Median effective dose: ED50 dose required to produce a specific effect in 50% of the subjects or the dose required to produce half of the maximum effect.
  3. The higher the potency, the lower ED50
46
Q

Describe efficacy

A
  1. The maximum intensity of therapeutic effect that can be produced by a drug.
  2. Not dose dependent
47
Q

Describe therapeutic dosage of drugs

A
  1. The goal is the select a dose within the therapeutic range and avoid toxic dosage
  2. Amount of drug at action site is affected by - route of administration, absorption, drug metabolism, patient factors (patient compliance, time and route of administration, age/sex. size/weight, state of health
48
Q

Describe mechanism of action of the drugs

A
  1. After drug distribution, pharmacological effect occur at cellular level.
  2. Drugs do not create a new function to the organism - They produce the same action as or Block the action of an endogenous agent
  3. Drug action begins after the drug is attached to receptor site.
49
Q

Describe drug receptors

A
  1. The attachment or binding of a drug to its receptor site begins a series of cell changes referred to as the drug action.
  2. Specific sites will elicit a desired therapeutic response. The site of action of many drugs is, however, not known
  3. Non-specific site will elicit no response (storage for later) or elicit an undesirable effect (side effect).
  4. Drugs that bind to a specific receptor and produce a specific drug action are called agonists
  5. Drugs that bind to a specific receptor but do not produce any drug action are called antagonists. They are usually blocking drugs because they bind the receptor and prevent other drugs from producing an effect.
50
Q

Describe chemical signaling between cells

A
  1. Local substances: secreted by organs, not released in systemic circulation. Prostaglandines(uterus, stomach), histamine(skin)
  2. Hormones: insulin, thyroid h., corticosteroids, FSH, LH. Produce effects throughout the body
  3. Neurotransmitters: chemicals that transport a wide variety of messages across the synapse to the receptor: acetylcholine, norepinephrine/epinephrine, dopamine, serotonin, GABA(gamma-aminobutyric acid), histamine

Pharmacology (15 decks)

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