drugs and histamine receptors Flashcards Preview

Yr 2 - Pharmacology > drugs and histamine receptors > Flashcards

Flashcards in drugs and histamine receptors Deck (73)
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1

What 4 conditions occur when inflammation goes wrong?

  • Anaphylaxis
  • Asthma
  • Rheumatoid arthritis
  • Atherosclerosis

2

Which step of inflammation do medicines such as steroid, antihistamines and anti-inflammatory drugs target?

Release of chemical mediators

3

Which 2 mediators cause vasodilation?

  • Histamine
  • Prostaglandins (PGE2 & PGI2)

4

Which 2 mediators cause increased vascular permeability?

  • Histamine
  • Platelet activating factor (PAF)

5

Which 4 mediators cause exudation (fluid filtering from circulatory system into the surrounding tissue)?

Plasma proteins:

  • Complement
  • Coagulation system
  • Fibrinolytic system
  • Kinin system

6

What are the 7 principle mediators/autocoids/local hormones of inflammation and allergy?

- Histamine

- Platelet Activating Factor

- Bradykinin

- Nitric Oxide

- Cytokines (interleukins, interferons, chemokines, colony stimulating factors)

- Eicosanoids (prostagladins, thromboxanes, leukotrienes)

- Plasma proteins (kinins, complement, coagulation and fibrinolytic factors)

7

When are these mediators released?

From cells upon stimulation

8

How is histamine synthesised?

Decarboxylation of histamine by L-histadine decarboxylase

9

Which 2 enzymes rapidly metabolises histamine?

n.b. they produce two different products

Histamine-N-methyltransferase

or

Diamine oxidase/histaminase

10

How many different types of histamine receptor subtypes have been discovered?

4

11

Which two types of celLs contain histamine contained in granules?

  • Mast cells
  • Basophils

12

Which cells in the gastric glands in the gastric mucosa are also found to contain histamine?

Enterochromaffin-like cells (ECL)

13

In which organs of the body can the highest levels of histamines be found?

Lung

Skin

Brain

GI tract

 

n.b. they are found throughout the body too!!

14

Where are mast cells produced?

Bone marrow

(released as immature cell and matures in the tissue)

15

Which antibody does the FCERI receptor have a high affinity for?

IgE

16

What are the 4 stages of mast cell degradation?

  1. Priming of mast cells (body produced IgE = bind mast cells = chemical mediator release)
  2. 2nd exposure to allergen = IgE bind to mast cell surface
  3. Activates mast cell (granule movement and fusion to membrane due to increased Ca)
  4. Degranulation (release of chemical mediators)

17

Which two other factors can activate mast cells?

Complement components:

C3a

C5a

18

Which process gets the complement & phagocytes present mainly in the blood to the site of tissue invasion?

Inflammatory response

19

What 2 things can cause histamine release?

  • Some neuropeptides (e.g. substance p)
  • certain basic drugs (e.g. morphine & tubocurarine)

 

n.b. some basic drugs e.g. morphine and other opioids can displace histamine from mast cells without activating cell surface receptors

20

What inhibits histamine release?

An increase in cAMP

e.g. by beta adrenoreceptor agonists

21

What are the 3 physiological roles of histamine?

  • local immune response (tissue repair, inflammation, control of local blood flow, allergies & anaphylaxis)
  • regulates physiological function in the gut (increased gastric acid secretion = H2)
  • Neurotransmitter in CNS

22

Why is the reaction to histamine location dependant?

  • different histamine receptors

(all GPCRs) = H1, H2, H3 & H4

(located in different tissues & couple different G proteins)

23

What type of receptor is the H1 receptor?

And where is it found?

GPCR - Gq

 

= activates PLC & PIP2

Found in smooth m, endothelium & CNS tissue

24

Activation of the H1 receptor causes (8):

- Bronchial smooth muscle contraction

- vasodilation

- separation of endothelial cells

- increased vascular permeability

- pain and itching

- motion sickness

- allergic rhinitis

- sleep and appetite suppression

25

What are H1 receptor antagonists used for?

  • Treat allergy (hay fever, urticaria)
  • Treat nausea and vomiting

26

How H1 receptor antagonists drugs taken?

Where are they metabolised?

Orally

Hepatic metabolism

27

Name 3 1st generation H1 receptor antagonists?

- Mepyramine

- Promethazine

- Diphenhydramine

28

What is the average duration of effect for H1 receptor antagonists?

Approx 4-6 hours

29

What is promethazine used for (4)?

- Allergic disorders

- Nausea and vomiting

- Insomnia

- Sedation

30

What is Diphenhydramine used for (4)?

Antihistamine with:

  • Anticholinergic
  • Antitussive (prevents coughing)
  • Antiemetic (prevents nausea)
  • Sedative