Anti-Histamine

Question 1

Histamine antagonists:

Answer 1

occupy receptors of the effector cells in a COMPETITIVE and REVERSIBLE manner. DON’T USE HISTAMINE ANTAGONISTS WITH OPIATES AND ATROPINE.

Question 2

Histamine1 blockers:

Answer 2

ethylamine derivatives. Inhibits pain and itching, inflammatory response on vessels/smooth muscle. Hypotension via constricting SM. salivary stim, adrenal cells. Stopping the increase of IP3/DAG. OTHER: anesthetic activity, cardiac depressant.
AA: sedation and drowsiness, increased appetite, dry mouth/xerostomia, urinary retention, allergic dermatitis, dyscrasias, teratogenicity(piperazine group), cute poisoning(hallucination, ataxia, coma). Thru peepee.

Question 3

1st gen histamine blockers

Answer 3

are strong in sedation, at autonomic receptors(musc). AA: sedation and drowsiness
Diphenhydramine
Chlorpheniramine
promethazine

Question 4

2nd gen histamine blockers

Answer 4

Have less CNS pen, longer active.INTERACTIONS: VTACH with a conazole, macrolides(eryth) hepatic dx, grapefruit juice
Loratadine(long acting)
Fexofenadine(lower arrhythmia risk).
Desloratadine
Cetirizine(carboxylated hydroxyzine), inhibits mast cell release
Terfenadine: inhibition of p glycoprotein transporter
Astemizole
Olopatadine (conjunctivitis)

Question 5

Histamine2 blockers/tidines

Answer 5

competitive antagonist of gastric acid secretion. Equal efficacy, different potency levels. Tx for PUD. INT: CYP450 inhibition, avoid anticholinergics and metoclopramide. AA: mental status change, excreted in milk, Leukopenia.

Question 6

Cimetidine

Answer 6

2 hr peak. Oral, kidney excretion. 3 wk relief period.. Excreted in MILK. gynecomastia, inhibits dihydrotestosterone to androgen, impotence, galactorrhea.

Question 7

Famotadine

Answer 7

20-50x cim. Minimum cns effect

Question 8

Ranitidine:

Answer 8

minimum cns effect