Methyl Xanthines

Question 1

Naturally occurring methylated xanthine alkaloids

Answer 1

Caffeine, theophylline, theobromine

Question 2

Chemically caffeine is

Answer 2

1,3,7 Trimethylxanthine

Question 3

Chemically theophylline is

Answer 3

1,3 Dimethylxanthine

Question 4

Chemically theobromine is

Answer 4

3,7 Dimethylxanthine

Question 5

Why is caffeine used in a migraine?

Answer 5

Although methyl xanthines dilate systemic blood vessels, they have a constricting effect on cranial blood vessels especially by caffeine

Question 6

What is the effect of caffeine on smooth muscles and skeletal muscles respectively?

Answer 6

Relaxation and contraction(at toxic doses)

Question 7

Mechanism of action of methyl xanthines

Answer 7

1. Inhibition of phosphodiesterase(PDE)
2. Blockade of adenosine receptors
3. Release of calcium ion from SER(exerted only at concs. much higher than therapeutic plasma conc.)

Question 8

Therapeutic range of theophylline

Answer 8

7 to 17 mcg/ml (Narrow)

Question 9

Examples of enzyme inducers

Answer 9

Rifampicin, phenytoin, phenobarbitone

Question 10

Examples of enzyme inhibitors

Answer 10

Erythromycin, cimetidine, ciprofloxacin

Question 11

Aminophylline is

Answer 11

Theophylline - ethylenediamine; 85% theophylline

Question 12

Anticholinergics used in bronchial asthma

Answer 12

Ipratropium bromide and tiotropium bromide

• block effects of ACh in bronchial smooth muscles leads to bronchodilatation
• do not affect mucociliary clearance
• slow onset of action
• act primarily on larger airways
• preferred bronchodilators in COPD

Question 13

Leukotriene antagonists

Answer 13

MonteLUKast and zafirLUKast

• antagonize cysLT1 receptor
• bronchodilatation, reduced mucus secretion, reduces sputum eosinophil count, suppression of bronchial inflammation

Question 14

Rare side effect of LT antagonists

Answer 14

Churg-Strauss syndrome

-vasculitis with eosinophilia

Question 15

Mast cell stabilizers and uses

Answer 15

Sodium cromoglycate and ketotifen

-used in allergic asthma, allergic conjunctivitis, allergic rhinitis, allergic dermatitis

Question 16

Drugs to be avoided in ashmatic patients

Answer 16

1. NSAIDs like aspirin, ibuprofen, diclofenac (PARACETAMOL can be used)
2. Beta adrenergic blockers
3. Cholinergics