Pharmacokinetics 1 Flashcards

studying how the body handles drugs.

1
Q

What is Pharmacology divided into?

A

Classically - divided into
Pharmacokinetics and Pharmacodynamics

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2
Q

Summarize the essence of pharmacokinetics.

A

Pharmacokinetics involves studying the time course of drugs and their metabolites in the body, focusing on what the body does to the drug.

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3
Q

What are the key processes involved in pharmacokinetics?

A

The key processes in pharmacokinetics include administration, absorption, distribution, metabolism, and excretion.

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4
Q

What does administration refer to in the context of drugs?

A

Administration is the delivery of a drug to the body.

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5
Q

: Define absorption in relation to drug pharmacology.

A

Absorption is the movement of a drug across membranes.

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6
Q

How would you describe distribution in the context of drug pharmacokinetics?

A

Distribution is about how a drug spreads and enters different compartements of the body.

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7
Q

What is metabolism when it comes to drugs?

A

Metabolism refers to the chemical alteration of a drug.

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8
Q

Explain elimination in the context of drug pharmacokinetics

A

Elimination is the transfer of the drug from inside the body to the outside.

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9
Q

What does pharmacokinetics help to describe?

A

pharmacokinetics helps to describe the absorption from the site of administration, delivery to the site of action, elimination from the body, time to onset of effect, duration of effect, accumulation on repeat dosage, and drug interactions.

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10
Q

What are the 7 various surfaces and orifices through which the medical profession can administer medications?

A

The medical profession can exploit the following surfaces and orifices:
Oral (including buccal and sub-lingual)
Rectal
Skin (topical)
Lungs (including nose)
Eye, Ear
Urethra
Injection (if no convenient orifice is available)

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11
Q

What are the different routes of administration for injections?

A

Injections can be administered through the following routes:
Intramuscular
Subcutaneous
Intradermal
Intraperitoneal
Intrathecal
Intra-arterial

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12
Q

Why do we give a large dose of Paracetamol (1g) when 90% of it gets metabolized?

A

We use a large dose of Paracetamol because even though most of it gets broken down in the body, the liver’s ability to process it is limited. Giving a bigger dose ensures there’s enough to provide effective pain relief.

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13
Q

What is the function of the hepatic portal vein (HPV)?

A

The hepatic portal vein conducts blood from the GI tract to the liver.

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14
Q

Where do drugs administered orally usually pass through before reaching the liver?

A

Most drugs administered orally pass through the duodenum to the ileum before being transported to the liver by the hepatic portal vein.

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15
Q

What is the significance of the liver in drug administration?

A

Within the liver, drugs undergo First Pass Metabolism before entering the general circulation.

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16
Q

Define First Pass Metabolism in the context of drug administration.

A

First Pass Metabolism refers to the metabolic process drugs undergo within the liver before entering the systemic circulation.

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17
Q

Give an example of a drug that is completely metabolized during the first pass.

A

Glyceryl trinitrate is an example of a drug that undergoes complete metabolism during the first pass and may require alternative routes of administration.

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18
Q

What is a good indicator of how much drug is in the body?

A

Plasma [drug]

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19
Q

What factors determine the ability of drugs to reach systemic circulation when not administered intravenously?

A

1) Lipid solubility, 2) Area available for absorption, 3) Possible specific carriers.

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20
Q

What is “first pass” metabolism, and how does it affect the effectiveness of a drug?

A

“First pass” metabolism is a Biochemical change in the liver.
It Reduce the concentration of the active drug before it reaches the bloodstream.
Result: Compromises the amount of the drug that reaches the target site.

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21
Q

What are the advantages of the oral route of administration?

A

The oral route is safer and more convenient than injection. Drugs are absorbed through either passive or active transport.

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22
Q

When is the rectal route of administration useful?

A

The rectal route is useful in patients who are vomiting or unconscious. The rectal wall is well vascularized, allowing for drug absorption.

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23
Q

What is the advantage of buccal, sublingual, or nasal routes of administration?

A

These routes help avoid presystemic metabolism of drugs.

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24
Q

What is a route of administration that is becoming more popular and helps in avoiding presystemic metabolism?

A

Transdermal

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25
Q

Which organ provides a large surface for gaseous exchange, making it suitable for the administration of volatile anaesthetics?

A

Lungs

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26
Q

What is the advantage of administering drugs through the transdermal route?

A

It avoids presystemic metabolism.

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27
Q

What is the primary access point for asthma treatments targeting bronchial smooth muscle?

A

Lungs

28
Q

Name a drug used for asthma treatment that acts on bronchial smooth muscle

A

Salbutamol

29
Q

What type of drugs are used to block the effects of acetylcholine in the treatment of asthma?

A

Muscarinic antagonists

30
Q

What class of drugs is commonly used for reducing inflammation in the lungs in conditions like asthma?

A

Inhaled corticosteroids

31
Q

Why is the lung route preferred for certain medications?

A

It decreases systemic side effects.

32
Q

What is the route of administration that is useful for insulin, heparin administration, and immunizations?

A

Subcutaneous

33
Q

How is subcutaneous administered?

A

A subcutaneous injection is given into the subcutaneous fat under the skin

34
Q

What are the common sites for intramuscular injections, and what caution should be taken in the gluteus maximus region?

A

Common sites include biceps, quadriceps, and gluteus maximus. Caution should be taken in the gluteus maximus region to avoid the sciatic nerve.

35
Q

Why is intramuscular injection useful in emergencies?

A

Intramuscular injection is useful in emergencies because muscles have a good blood supply, hastening absorption of the administered substance.

36
Q

What is the purpose of administering Pethidine through intramuscular injection?

A

Pethidine is administered intramuscularly for pain relief in childbirth.

37
Q

What type of injections are suitable for slow-release preparations, and why is intramuscular administration preferred for depot injections?

A

Depot injections (slow-release preparations) are suitable for intramuscular administration because muscles have a good blood supply, facilitating slow release

38
Q

How does the absorption of substances through intramuscular injection differ in cases of shock?

A

Absorption is slower in cases of shock when intramuscular injection is used.

39
Q

What is the route of administration that is very useful in emergencies for rapid reactions, but potentially dangerous if administered too quickly?

A

Intravenous (I.V.)

40
Q

Why is intravenous administration considered potentially dangerous if too rapid?

A

Too rapid administration can lead to a high concentration reaching the heart, posing a risk.

41
Q

Is intravenous administration easily reversed?

A

No, I.V. administration is not easily reversed.

42
Q

In which medical situation is epidural administration commonly used?

A

Epidural administration is commonly used for pain relief in childbirth.

43
Q

Where is lignocaine injected during epidural administration?

A

Where is lignocaine injected during epidural administration?

44
Q

What is the route of administration that pierces the dura mater and goes directly into the central nervous system, posing a high risk?

A

Intrathecal administration.

45
Q

How does intrathecal administration bypass the blood-brain barrier?

A

It bypasses the blood-brain barrier by injecting into the subarachnoid space

46
Q

What is the major fluid that intrathecal administration mixes with and bathes the brain and spinal cord?

A

It mixes with cerebrospinal fluid (CSF).

47
Q

how is the Intrathecal injection, administrated?

A

a route of administration for medicines via an injection into the spinal canal, or into the subarachnoid space so that it reaches the cerebrospinal fluid (CSF)

48
Q

What are the characteristics of Intraperitoneal administration?

A

Large surface for relatively rapid absorption into the circulation.
Requires much skill to avoid gut hemorrhage.
Primarily used in veterinary practice.

49
Q

What is the primary advantage of Topical administration?

A

Direct administration to the site of desired therapeutic effect.
Examples include eyedrops and skin creams.

50
Q

How does Hydrocortisone work in topical administration?

A

Dampens down local inflammation in conditions like eczema.
Helps avoid systemic side effects associated with oral corticosteroid administration.

51
Q

Why is the topical route considered the best, but not always possible?

A

Best for localized effects.
Not always possible due to factors like accessibility or the nature of the condition being treated.

52
Q

What does the term “Bioavailability (F)” refer to in pharmacology?

A

Bioavailability (F) is a measure that defines how well a drug is absorbed and reaches its site of action.

53
Q

How is bioavailability (F) typically determined?

A

Bioavailability is usually determined by comparing oral and intravenous (IV) absorption

54
Q

What does “Half-life (T₀.₅)” refer to in pharmacology?

A

the time it takes for the plasma drug concentration to fall to half its original value.

55
Q

Is the elimination of a drug linear or nonlinear?

A

Is the elimination of a drug linear or nonlinear?

56
Q

Is the elimination of a drug linear or nonlinear?

A

T₀.₅ (Half-life)

57
Q

How is clearance in pharmacology defined?

A

Clearance is the rate of elimination divided by plasma drug concentration.

58
Q

What information does the removal of a drug from plasma provide?

A

Removal of a drug from plasma gives information on the behavior of the drug in the system.

59
Q

How would drug elimination behave if it were linear?

A

If drug elimination were linear, we would observe a straight line.

60
Q

What is zero order kinetics?

A

Zero order kinetics is a type of drug elimination where the rate of elimination is constant, regardless of the drug concentration.

61
Q

Do many drugs exhibit zero order kinetics?

A

No, few, if any at all, behave in this way.

62
Q

What does T0.5 depend on on a zeron order kinetics?

A

T0.5 depends on the amount of drug given.

63
Q

What type of kinetics do most drugs follow for elimination?

A

Most drugs are eliminated with first order kinetics.

64
Q

What does the rate of removal of a drug with first order kinetics depend on?

A

The rate of removal depends on how much drug is present. More drug leads to an increased rate of removal, while less drug results in a decreased rate of removal.

65
Q

Is the T0.5 constant in first order kinetics?

A

Yes, the T0.5 (half-life) is constant in first order kinetics.

66
Q

What is removed in unit time in first order kinetics?

A

A constant fraction of the drug is removed in unit time in first order kinetics.