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Pharmacology MBBS > General Pharmacology part 2 > Flashcards

General Pharmacology part 2 Flashcards

1
Q

Avd of a drug, definition

A

It is the total plasma required to accommodate the administered drug in the whole body at plasma concentration
Avd = (Dose*f)/conc

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2
Q

Loading dose

A

It is the high dose of drug given for drugs with high volume of distribution to maintain a specific plasma concentration
Loading dose = (avd*conc)/f

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3
Q

Factors which affect avd of a drug

A
  1. Lipid solubility
  2. Fat content (hence gender and age)
  3. Plasma protein binding
  4. Specific tissue binding
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4
Q

Digoxin accumulates in which organ

A

Skeletal muscle

Therefore avd is calculated based on lean body mass

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5
Q

Dialysis is not effective in removing toxicity in which cases

A
  1. Increased avd
  2. High plasma protein binding capacity
  3. Which are irreversible binders
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6
Q

Examples of drugs whose toxicity cannot be treated by dialysis

A

O) Opioid and organophosphates

A) Amphetamine
B) Benzodiazepines and beta blockers
C) Ca channel blockers
D) Digoxin

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7
Q

Antidote of benzodiazepines and beta blockers

A

For benzodiazepines it is flumazenil

For beta blockers it is glucagon (source of cAMP)

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8
Q

Antidotes of amphetamines, digoxin and Ca channel blockers

A

Antidote of amphetamine- ammonium chloride

Antidote of digoxin- digiband

For Ca channel blockers it is Ca gluconate

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9
Q

Antidote for opioids and organophosphates

A

Antidote for opioids is naloxone

Antidote for organophosphates is atropine

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10
Q

Free drugs that bind to albumin

A

C. Most CNS drugs like antipsychotics, anti epileptics, benzodiazepines
A. Antibiotics (sulfonamides and penicillin)
N. NSAIDs
W. Warfarin
A. Aspirin
S. Some other examples are also there
Hence warfarin blocks aspirin and vice versa

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11
Q

Drugs that bind to alpha 1 acid glycoprotein

A
  1. Opioids
  2. TCA Tricyclic antidepressants
  3. Anti-arrhythmics (lidocaine, amiodarone, beta blockers)
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12
Q

Conditions in which albumin decreases leading to toxicity of such drugs

A

Nephrotic syndrome
Liver cirrhosis
Chronic kidney disease

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13
Q

Conditions in which there is an increase in alpha 1 acid glycoprotein which leads to decreased efficacy of such drugs

A

Rheumatoid arthritis
Inflammatory bowel disease
Myocardial infarction

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14
Q

Examples of prodrugs

A 
Levodopa
All ACE inhibitors except captopril and lisinopril
Clopidogrel
Famciclovir (antiviral)
Carbimazole (anti thyroid)
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15
Q

Primary purpose of phase 2 of drug metabolism

A

The purpose is to make the drug by conjugation:

  1. Water soluble
  2. Ionised
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16
Q

Functions of phase 1 of drug metabolism

A
  1. Usually drug inactivation
  2. For some drug, it is activation
  3. In the latter part of phase 1 , the water solubility in increased (though by a small amount) by addition of a functional group to the drug
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17
Q

Phase 1 reactions of drug metabolism

A 
O. Oxidation
R. Reduction
C. Cyclisation
H. Hydrolysis
A. Aliphatic or aromatic hydroxylation
D. Deamination
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18
Q

Phase 2 (conjugation) reactions of drug metabolism

A

G. Glucuronation, glycination , glutathionation
A. Acetylation
M. Methylation
S. Sulfation

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19
Q

Most common reactions of phase 1 and phase 2 of drug metabolism

A

For phase 1: oxidation

For phase 2: glucuronidation

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20
Q

Which reactions in drug metabolism are microsomal and which are not

A

All reactions of phase 1 (mediated by cytochrome p450) and glucuronidation of phase 2 reactions is microsomal
Rest are non-microsomal

21
Q

What does P450 in CYP450 stand for

A

The P stands for pigment and the 450 for the wavelength of light absorbed by the pigment

22
Q

Nomenclature of cytochrome p450. Example CYP1A2

A

The 1 stands for the family. The A stands for the subfamily.

The 2 stands for the G number

23
Q

Various cytochromes

A
  1. CYP1A2: TTT
  2. CYP2B6: CM
  3. CYP2C9: PW
  4. CYP2C19: OC
  5. CYP2D6: BOAT
  6. CYP2E1: EE
  7. CYP3A4
24
Q

Drugs which are metabolised by CYP1A2

A

Tamoxifen
Tacrine
Theophylline

25
Q

Drugs which are metabolised by CYP 2B6

A

Cyclophosphamide

Methadone

26
Q

Drugs which are metabolised by CYP2C9

A

Phenytoin

warfarin

27
Q

Drugs which are metabolised by CYP2C19

A

Omeprazole
It activated clopidogrel
Note:
Omeprazole (used for treating MI) inhibits clopidogrel (used for treating peptic ulcer)

28
Q

Drugs which are metabolised by CYP2D6

A

Beta blockers antidepressants (TCA, SSRI)
antipsychotics
opioids-tramadol
Activates Tamoxifen

29
Q

Drugs which are metabolised by CYP2E1

A

Ethanol

Enflurane

30
Q

Drugs which are metabolised by CYP3A4 or

Substrates for P-gp

A

The most common for drug metabolism
Metabolises more than 50% of all drugs
Eg., protease inhibitor, statins, amiodarone, cisapride, oestrogen, mifeprestone, erythromycin

31
Q

Atazanavir and irinotecan contradicted in Criggler Najjar syndrome. Why?

A

These drugs are highly toxic drugs and contradicted in Criggler Najjar syndrome there is a deficiency of glucuronyl transferase

32
Q

Conjugation of drugs

Types

A
  1. Glucuronidation: BAISO
  2. Glutathionation: IF
  3. Glycination: N
  4. Acetylation: SHIPD
  5. Methylation: MM
  6. Steroids: S
33
Q

Drugs which are conjugated via glucuronidation

A 
Benzodiazepines 
Azatanavir
Irinotecan
statins
oestrogen
34
Q

Why is conjugated oestrogen is not excreted

A

Estrogen glucuronide When it reaches the colon the bacteria secretes glucuronidase which unconjugates the estrogen
This causing enterohepatic circulation

35
Q

Antibiotics cause OCP failure. Why?

A

The antibiotics kill the bacteria which secretes glucuronidase inhibits enterohepatic circulation.
The oestrogen levels fall causing OCP failure

36
Q

Drugs metabolised by glutathionation

A

Ifosfamide

Fosfomycin

37
Q

Drugs metabolised by glycination

A

Niacin

38
Q

Drugs metabolised by acetylation

What is their side effect

A 
Sulphonamides 
Hydralazine 
Isoniazid
Procainamide
Dapsone
Side effect is SLE (systemic lupus erthematosus)
39
Q

Drugs metabolised by methylation

A

6-mercaptopurine
Methyldopa
MM

40
Q

Steroids are conjugated by

A

Sulfation

41
Q

Drugs which are microsomal enzyme inducers

A 
G. Griseofulvin
R. Rifampin (imp)
A. Alcohol (chronic)
B. Benzpyrene
P. Phenytoin, phenobarbital, primidone 
C. Carbamazepine 
Can cause OCP failure
42
Q

Drugs which can cause folic acid deficiency when taken for a long time

A

Most anti-epileptics like phenytoin, phenobarbital, primidone,carbamazepine cause folic acid deficiency especially when taken for a long time.
These are microsomal enzyme inducers

43
Q

Substances other than drugs which cause microsomal enzyme induction

A

DDT

A plant called St. John’s wort

44
Q

Examples of microsomal enzyme inhibitors are

A 
Q. Quinidine
I. Isoniazid (sometimes inducer, sometimes inhibitor)
C. Cimetidine 
K. Ketoconazole
V. Valproate 
E. Erythromycin
G. Grape fruit juice
D. DEC
45
Q

Application of microsomal enzyme inhibitors

A

When ketoconazole (a microsomal enzyme inhibitor) is given with terpenadine (QT elongation), the usually asymptomatic drug causes torsades and death

46
Q

Application of microsomal enzyme inducers

A

When a young girl on OCP is given rifampicin for tuberculosis, it may cause pregnancy

47
Q

Phases of clinical trials

A
  1. Human pharmacology and toxicity study
  2. Therapeutic exploratory trial
  3. Therapeutic confirmatory trial
  4. Post marketing surveillance
    (5. Pharmacoepidemiology
  5. Microdosing )
48
Q

Adverse effects of drugs

A
  1. Side effects
  2. Secondary effects
  3. Toxic effects
  4. Intolerance
  5. Idiosyncrasy
  6. Allergy
  7. Photosensitivity
  8. Dependence and addiction
  9. Withdrawal reactions
  10. Teratogenicity
  11. Mutagenicity and carcinogenicity
  12. Drug induced diseases

Pharmacology MBBS (19 decks)

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