Pharmacological basis of therapy Flashcards

1
Q

Antagonist affinity

A

Measure of how well a drug binds to a receptor

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2
Q

Prostaglandin analogue

A

Misoprostol - agonist at PG receptors
Suppress acid release + promote cytoprotection
Cause uterine contractions

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3
Q

Prokinetic drugs

A

Cause gastric emptying - movement of gastric contents from stomach to duodenum (help GORD)

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4
Q

Example of prokinetic drugs

A

DOMPERIDONE

METOCLOPRAMIDE

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5
Q

What can metoclopramide be combined with?

A

Analgesics - to accelerate absorption

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6
Q

How do we eradicate H.pylori?

A

Triple therapy

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7
Q

What is triple therapy?

A

Combination therapy

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8
Q

What does triple therapy consist of?

A

2 antibiotics + PPI and/or H2RA

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9
Q

How long to take triple therapy?

A

1 week then PPI alone

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10
Q

Example of PPI

A

Omeprazole
Pantoprazole
Lansoprazole

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11
Q

What PPIs are OTC

A

Omeprazole + pantoprazole

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12
Q

Adverse effects of PPIs

A

Inhibit H+ secretion by more than 90% - leading to achlorydria
Increase risk of Campylobacter infection (food poisoning)

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13
Q

Adverse effects of PPIs

A

Inhibit H+ secretion by more than 90% - leading to achlorydria
Increase risk of Campylobacter infection (food poisoning)

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14
Q

What activates PPIs

A

Acidic pH

  • enters body
  • passes to parietal cells
  • pka means activated at low pH
  • localises action
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15
Q

What is rebound acid hypersecretion

A

Follows after cessation of H2RAs + PPIs
Increases acid release
Increase dyspepsia symptoms
Avoid prolonged usage

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16
Q

How do you treat/manage rebound acid hypersecretion?

17
Q

Affinity constant

18
Q

Dissociation constant

19
Q

Kd

A

Concentration at which the drug occupies half of the receptor population

20
Q

A high affinity drug has…

A

A low Kd (low molarity drug)

21
Q

Examples of H2RA

A

Cimetidine
Ranitidine
Nizatidine
Famotidine

22
Q

H2RA

A

Coupled with adenylyl cyclase to increase cAMP

which activates the proton pump

23
Q

Alginates

A

Combine with saliva to form viscous foam

Floats on gastric content forming a raft which protect oesophagus from reflux

24
Q

Examples of antacids

A

Sodium bicarbonate
Magnesium hydroxide
Aluminium hydroxide

25
Domperidone
Increased closure of oesophageal sphincter (good for reflux) + opens lower sphincter
26
Metoclopramide
Acts locally to increase gastric motility + emptying
27
What are the antibiotic that can be used for triple therapy
Amoxicillin Clarithromycin Metronidazole
28
Calculate pA2
-logKd
29
Use of H2RAs
Reduce gastric acid secretion - provide symptomatic relief - promote ulcer healing - reduce need of surgeru in ulceration
30
When are H2RAs best given
At night
31
Why does H2RAs have a lot of drug interactions
Inhibit cytochrome P450 + metabolism of drugs = drug interactions
32
What drugs metabolism are affected by H2RAs
Oral anticoagulants Phenytoin Carbamazepine Tricyclic anti-depressants
33
What H2RA does not interact with other drugs
Ranitidine
34
Misoprostol
Agonist at PG receptor | Suppress acid secretion + promote cytoprotection
35
What do misoprostol cause
Uterine contractions
36
What are uterine contractions contra-indicated with
Females of child-bearing age
37
How do we accelerate absorption of metoclopramide
Combining it with analgesics