DRUGS ACTING ON THE
RESPIRATORY SYSTEM
Dr. Ragia M.Hegazy
MD CLINICAL TOXICOLOGY
Assistant professor of clinical toxicology
Faculty Of Pharmacy,
Umm Al-Qurra University
Drugs of resp. syst
Mucoactive agents
1-Expectorant
2-Mucolytics
3-Mucokinetics
4-Mucoregulatory agents
5-Others
Cough suppressants (antitussives)
1-Peripheral antitussives
2-Central antitussives(narcotic or non narcotic)
3-Central & peripheral antitussives
Respiratory Stimulants (analeptics)
1-Specific analeptics
2-Non-specific analeptics
MUCOACTIVE AGENTS
Types of cough
1. Use cough: productive treated by mucoactiveagents (expectorants, mucolytics, etc)
2. Useless cough: dry, non-productive not associated with sputum and treated by
antitussive
Mucoactive agents (dry cough ttt)
Are agents that help in airway clearance
They serve the purpose of either:
increase the ability to expectorate sputum
or
decrease mucus hyper-secretion
Mucoactive
agents
1-Expectorant
increase volume or hydration of airway
secretion
2-Mucolytics
1-classic mucolytics(NAC- L-cysteine)
2-SCMC
3-Proteolytic enzymes
3-Mucokinetics
stimulating
ciliary activity
1-Bronchodilators
2-Ipratrobium
3-Abhesives
4-Mucoregulatory
agents
1-Anti- inflam
2-Anticholinergic
3-Macrolide antibiotics
5-Others
1-Ambroxol
2-Saline
3-Na HCO3
Classification according to mechanism
of action
1-Expectorants: increase volume or
hydration of airway secretion
Systemic hydration no clinical effect
Classic expectorants no clinical effect
Modifier of airway water transport (being
investigated)
2-Mucolytics: degrade polymers in secretion
A. Thiols with free sulphydryl groups (classic mucolytics)
N- Acetyl Cysteine (NAC):
Disrupts disulfide bond making mucus less resistant
NAC can be taken orally, inhalation or instillation
Side effects:
1) GIT irritation (oral)
2) Burning sensation in airways (inhalation)
3) Bronchospasm (inhalation)
4) Sulphorous taste & odor (inhalation)
L-cysteine ethyl ester hydrochloride:
Given orally
Biotransformed in liver to NAC
Used in COPD
Has no GIT side effects
B. Thiols with blocked sulphydryl group
S- caboxymethyl cysteine (SCMC)
Does not break mucin disulfide bonds
Increases nasal mucociliary clearance in chronic sinusitis (not
in chronic bronchitis
C. Proteolytic enzymes (peptide enzymes)
They increases sputum viscidity
3-Mucokinetics: increase mucociliary efficiency or cough efficiency
Bronchodilators: they increase cough flow in patients with airway hyperactivity e.g. b2 agonist & theophyllineciliostimulant and bronchodilator
Ipratropium bromide has no anti-mucokinetic
Abhesives: such as surfactants
Pharmacological action Decrease mucus attachment to cilia and epithelium
Increase cough and mucociliary effect
Mucoregulatory agents: decrease the volume of airway mucus secretion
Effective in hypersecretory states (bronchorrhea and
bronchial asthma)
A. Anti-inflammatory agents: Iidomethacin &
corticosteroids
B. Anticholinergic agents
C. Macrolide antibiotics: erythromycin, clarithromycin,
and azithromycin
Long-term oral administration causes decrease in water and mucus secretion in airway
5- Other muco-active agents
A. Bromohexine & Ambroxol
Bromohexine increases expectoration of sputum in chronic bronchitis
Ambroxol stimulates mucus secretion and causes normalization of mucus viscosity in viscid secretion
B. Saline solution (isotonic, 0.9%) water causes Bronchospasm
Uses:
For routine nebulisation therapy
Hydration of mucus
C. Sodium bicarbonate (2%): alkaline environment causes decrease in mucus elasticity
If mucus secretion increases, viscidity decreases
Therapeutic uses of Mucoactive agents :
1. Respiratory mucostasis e.g. chronic bronchitis,
asthma & cystic fibrosis
2. Chronic sinusitis (+ antibiotics)
3. With antibiotics for treatment of airway infections
e.g. bronchiectasis
4. Prophylaxis of post-operative chest complications
5. Sputum production for diagnostic purposes e.g.
T.B.
COUGH SUPPRESSANTS
(ANTITUSSIVES)
Types of cough
1. Use cough: productive treated by mucoactiveagents (expectorants, mucolytics, etc)
2. Useless cough: dry, non-productive not associated with sputum and treated by
antitussive
Cough suppressants (antitussives)
Antitussives are drugs used in the treatment of dry
cough to suppress it (reduce input of stimuli arising
from pharynx, larynx & trachea). They include:
1- Peripheral antitussives
e.g. Liquorice, steam inhalation of tincture benzoincomposite and menthol
They have soothing effect on the irritant mucus membrane
2- Central antitussives
They inhibit the cough center
May be narcotics or non-narcotics
Narcotic antitussives:
Codeine & morphine: antitussive, analgesic, euphoric,
respiratory center depression & dependence
Pholcodeine and hydrocodone: weak addictive,
analgesic, euphoric & respiratory center depression
Non-narcotic antitussives:
1. Noscapine (natural opium alkaloid)
2. Dextromethorphan
Have no analgesic effect
No dependence
No euphoria
No respiratory center depression
3-Central & peripheral antitussives
Benzonatate
They inhibit cough center
They inhibit pulmonary stretch receptors
Antitussives
Peripheral antitussives
1-Liquorice lozenges,
2- steam inhalation of tincture benzoin
3-menthol
Central antitussives
1-Narcotic antitussives:
Codeine, Pholcodeine
2-Non-narcotic antitussives:
Noscapine
Central & peripheral antitussives
Benzonatate
RESPIRATORY STIMULANTS
(ANALEPTICS)
Respiratory Stimulants
(analeptics)
1-Specific analeptics
Naloxone with opiate toxicity
Flumazenil with BDZ toxicity
2-Non-specific analeptics
1-Direct brainstem stimulants e.g. xanthines (Theophylline)
2-Reflex brainstem stimulants Nicotine
3- Direct & reflex e.g. Doxapram
Respiratory Stimulants (analeptics)
They are drugs stimulating the CNS especially the
brainstem. They include:
1- Specific analeptics: used when respiratory
depression is due to certain drug overdose e.g.
Naloxone with opiate toxicity
Flumazenil with Benzodiazepine toxicity
2-Non-specific analeptics:
A. Direct brainstem stimulants e.g. xanthines
(Theophylline)
B. Reflex brainstem stimulants through stimulation of
chemoreceptors in carotid bodies & aortic arch e.g.
Nicotine
C. Direct & reflex e.g. Doxapram
Therapeutic uses of analeptics:
1. Treatment of respiratory center inhibition
2. Treatment of cerebral cortex inhibition
Adverse effects of analeptics:
1. Tachycardia
2. Tachpnea
3. Hypertension
4. Toxic dose causes convulsions
Contraindications of analeptics:
1. Epilepsy
2. Ischemic heart disease
3. Hyperthyroidism
4. Hypertension
WHAT ARE THE DRUGS ACTING
ON THE RESPIRATORY
SYSTEM????
What categories of drugs are used as
bronchodilators
Beta agonists
Methylxanthine derivatives
Anticholinergics
Which nonselective beta agonist is
most effective as a bronchodilator
Isoprenaline (isoproterenol)
Why are beta 2 agonists the best
drugs for bronchial asthma
Bronchodilator
And decongestant, anti-inflammatory, and
increases mucociliary clearance
What are the side effects of beta
agonists as bronchodilators
Tachycardia **
Hypotension
Hyperglycemia
Hypokalemia
Muscle tremors
Uterine relaxation
what is the clinical use of
leukotriene inhibitors
Orally for prophylaxis and chronic tx of
bronchial asthma in humans
Montelukast, & Zafirlukast
Zilleuton used to be used but not anymore
because it increases liver enzymes
What is the mechanism of action of
antihistamines in BA
Act by competitive antagonism to H1
receptors
What are uses of antihistamines
Chronic resp disease because of their effects
on the bronchial secretions
Not useful in the control of asthma
What are antitussives
Decrease the frequency and severity of
nonproductive cough without impairing
mucociliary defenses
What drugs are narcotic antitussives
Codeine
Hydrocodone
Morphine
Are the narcotic antitussives
centrally acting or peripherally
acting?
Centrally acting
What are the non narcotic centrally
acting antitussives
Dextromethorphan
Noscapine
What are the peripherally acting
antitussives
Bronchodilators
Mucokinetics
What are mucokinetic drugs
Drugs that facilitate the removal of secretions
from the resp tract
What is the mechanisms of action of
mucokinetic drugs
Act by stimulating ciliary action
Act by decreasing viscosity of bronchial
secretions
Which mucokinetic drugs act by
stimulating ciliary activity
Beta agonists
Methylxanthines
Which mucokinetic drugs act by
decreasing viscosity of bronchial
secretions Hydration
Saline, sterile water
Increasing pH
Bicarb
Breaking the disulfide linkages in the mucus
Acetylcysteine
What is another use for
acetylcysteine
Antidote for APAP toxicity
What are expectorants
Drugs which increase the volume and fluidity
of resp secretions
What are the mechanisms of action
of expectorants
Act reflexly by irritation of gastric mucosa
Cause direct stimulation
What is the classification
decongestants
Vasoconstrictors Phenylephrine, oxymetazoline, xylometazoline,
naphazoline) ( 1 agonist), ephedrine ( & agonists
), pseudoephedrine, phenylpropanolamine (norephedrine
and oxyamphetamine)
H1 antagonists
Diphenhydramine, hydoxyzine, chlorpheniramine,
promethazine, cyproheptadine
Cromolyn sodium (intal)
Glucocorticoids
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