Histamine and steroids

What amino acid is histamine derived from?

Histidine

Which cells mainly store histamine?

Mast cells basophils and neutrophils

What physiological functions does slow histamine release help regulate?

Gut cardiovascular and lung function

What can massive histamine release cause?

Anaphylaxis

What happens to blood pressure during anaphylaxis?

Massive drop in blood pressure

Which histamine receptor is mainly involved in allergic responses?

H1 receptor

What effect does H1 receptor activation have on the lungs?

Bronchoconstriction

What effect does H1 receptor activation have on gut smooth muscle?

Contraction

What effect does H1 receptor activation have on blood vessels?

Vasodilation and increased vascular permeability

What happens to blood pressure after H1 receptor activation?

Blood pressure decreases

What sensory effect can histamine cause?

Itching

What causes redness and swelling during inflammation?

Histamine induced vasodilation and increased vascular permeability

What is oedema?

Fluid accumulation in tissues

Name two gastrointestinal effects of histamine release.

Vomiting and diarrhoea

What are the major systemic effects of severe histamine release?

Huge vasodilation and bronchoconstriction

What type of drugs are used to relieve bronchoconstriction in severe allergic reactions?

Beta adrenoceptor agonists

What drugs block histamine H1 receptors?

Antihistamines

Name two older antihistamines.

Promethazine and chlorpheniramine

Do older antihistamines cross the blood brain barrier?

Yes

Why do older antihistamines cause sedation?

They cross the blood brain barrier

What additional receptor blocking effect do older antihistamines have?

Antimuscarinic effects

Name two newer antihistamines.

Loratadine and fexofenadine

Do newer antihistamines readily cross the blood brain barrier?

No

Why are newer antihistamines less sedating?

They do not readily cross the blood brain barrier

What are common uses of antihistamines?

Allergy treatment sedation cough and cold remedies and anti emetic use

Name three common side effects of antihistamines.

Dry mouth blurred vision and sedation

What type of steroid drugs are prednisone and beclometasone?

Glucocorticoids

How do glucocorticoids reduce inflammation?

They alter gene expression

What enzyme activity is decreased by glucocorticoids?

Phospholipase A2 activity

What inflammatory enzyme expression is decreased by glucocorticoids?

Cyclooxygenase COX expression

What is a major metabolic side effect of glucocorticoids?

Diabetes

What bone disease can glucocorticoids cause?

Osteoporosis

What gastrointestinal complication can glucocorticoids cause?

Peptic ulcers

How do glucocorticoids affect the immune system?

They cause immunosuppression

What endocrine complication can prolonged glucocorticoid use cause?

Adrenal suppression

What body appearance changes can glucocorticoids cause?

Weight gain on face and trunk with wasted limbs

What psychiatric effect can glucocorticoids cause?

Mental disturbance

What skin effect can topical steroids cause?

Skin atrophy

What hair related side effect can topical steroids cause?

Excess hair growth