Drugs used for treatment of Asthma

Question 1

Classification?

Answer 1

1. Corticosteroids. (Css)
2. Selective β2 agonists.
3. Antimuscarinic drugs. (Anticholinergic)
4. Phosphodiesterase inhibitors (methylxanthines).
5. Mast cell stabilizers.
6. Leukotriene modifiers.
7. Anti IgE drugs

Question 2

Pharmacokinetics of these drugs?

Answer 2

1. Corticosteroids: Administered by inhalation.
2. Selective β2 agonists: Good oral absorption, extensive FPM so low bioavailability. Oral-children, inhalation- adults.
3. Anti-muscarinic drugs: Administered topically on nasal mucosa, has poor systemic absorption.
4. PDE inhibitors (Methylxanthines): Oral and IV administration, no FPM, narrow therapeutic range and requires careful monitoring.
5. Mast cell inhibitors: oral and inhalation types
6. Leukotriene modifiers: Oral administration, BBB-BPB distribution and hepatic metabolism.
7. Anti-IgE drugs: Parenteral administration only.

Question 3

Pharmacodynamics of these drugs?

Answer 3

1. Corticosteroids: “LIPOCORTIN” synthesis (inhibits phospholipase A2” which inhibits production of PG,s and leukotrines, hence anti-inflammatory and anti-allergic effects. In asthma they reduce bronchial hypersensitivity reaction to the AB-Ag complex formation.
2. Selective β2 agonists: Relaxation of bronchial smooth muscle.
3. Antimuscarinic drugs: Inhibit the “muscarinic” effects of (increased secretion and brochoconstriction.
4. Methylxanthines: Inhibition of histamine and other mediators.
5. Mast cell inhibitors: inhibit secretions of the mast cell such as histamine to reduce inflammation in asthma.
6. Leukotriene modifiers: Inhibition of 5-lipoxygenase enzyme, reduced formation of leukotrienes (reduced inflammation and contraction of the bronchial muscles)
7. Anti-IgE drugs: Function to inhibit the binding of the IgE to mast cells, reducing histamine release.

Question 4

Therapeutic uses of the Asthma drugs?

Answer 4

1. Corticosteroids: “long acting drugs” (controllers of the effects of the asthma), used during asthmatic attacks.
2. Selective β2 agonists: Both “short acting drugs” (relief of symptoms DURING attack of asthma) and “long acting” for the control of asthma symptoms BETWEEN attacks.
3. Anti-muscarinic drugs: Reduce mucus secretion and bronchoconstriction caused by muscarinic receptor stimulation.
4. Methylxanthines: Acute severe asthma treatment.
5. Mast cell inhibitors: JUST PREVENTION of asthma attacks in induviduals.
6. Leukotriene modifiers:”Long acting” drugs (controller drugs).
7. Anti-igE drugs: Treat moderate to severe asthma.

Question 5

Adverse effects of the Asthma drugs?

Answer 5

1. Corticosteroids: local effects- Oropharyngeal candidiasis / systemic effects: Increased intra-ocular pressure, cataract, hyperglycaemia and osteoporosis.
2. Selective β2 agonists: : (THHHFT) - Tachycardia, hypertension, headache, hypokalaemia, finger tremor and TOLERANCE (reduced effect of same drug in future administrations).
3. Anti-muscarinic drugs: “Cholinergic effects” - Urinary retention, increased intra ocular pressure, xerostomia, mydriasis and tachycardia.
4. Methylxanthine: CNS - Headache, insomnia, tremor and convulsions.
5. Mast cell inhibitors: Cough reflexes on inhalation / pharyngeal discomfort.