Pharmacology cough Flashcards
Cough
Protective reflex that removes foreign material and secretions from the bronchi and bronchioles
What trigger cough
Inflammation in the respiratory tract
Undiagnosed asthma
Chronic reflex with aspiration
neoplasia
adverse effects of drugs such as angiotensin converting enzyme inhibitor’s
Cough physiology
Ion channel opening on vagus nerve due to signal (tRPV activation, cytokines release due to inflammation, mechanoreceptor from mass)
Nerve send signal to central cough generator
Central cough generator send signal to other nerves ( phrenic, recurrent laryngeal, spinal motor) to act in muscles for cough ( diaphragm, intercostal muscles, laryngeal muscles, abdominal muscle )
Two types of cough
Productive which expels secretion and exudates
unproductive due to local irritation
Class of drugs usedfor cough
Antitussives
Expectorants
Mucolytics
Antitussives action
Inhibit or suppress coughing so should not be used in productive cough
When are antitussives useful
Dry painful cough associated with bronchial carcinoma
When should you avoid Antitussives
Chronic pulmonary infection ( undesirable thickening and retention of sputum)
Asthma ( respiratory depression possible)
2 classes of anti tussives
Centrally acting
Peripherally acting
2 classes of centrally acting antitussive
Addicting
Non addicting
2 classes of addicting centrally acting antitussive
Potent addicting
Less potent addicting
Peripherally non addicting 2 sub classes
Opioid derivatives
Mon opioid derivative
Centrally acting antitussive MOA
Depression of medullary center or higher centres
Increased treshold of cough center
Peripherally acting antitussive MOA
Interruption of tussle impulses from respiratory tract
Soothing effect
Potent addicting central antitussive
Morphine
Dihydromorphinone
Less Potent addicting central antitussive
Codeine
Dihydrocodeine u
Pholcodine
Non addicting central antitussive opioid derivatives
Dextromethorphan
Noscapine
Non addicting central antitussive non opioid derivatives
Benzonatate
Diphenhydramine (1st gen antihistamine)
Peripheral antitussive pharyngeal demulcent
Natural : Pectin Glycerin Honey Syrup
Synthetic :
Methylcellulose
Propylene glycol
Glycerin
Peripheral antitussive steam inhalation
Tincture of benzoin/ menthol
Peripheral antitussive local anesthetic activity
Benzonatate
Lidocaine
Pharyngeal demulcents
Soothing action on irritated mucosa
Benzonatate action
Both central and peripheral also have anesthetic effect on stretch receptor
Peripheral antitussive use
Dry unproductive cough
If cough unduly and tiring
Disturbs sleep
Hernia ,piles of abdominal surgery
Codeine action
Increase treshold for cough
Codeine time of action
Suppress cough for 6h
Antagonist of codeine
Naloxone which suppresses antitussive action
Adverse effect of codeine
Constipation Respiratory depression Drowsiness Impaired driving Not used in asmathicd and low respiratory reserve
Pholcodine action ( homocodeine)
Centrally suppress center in medulla
Duration action of pholcodine
Longer acting - 12h
Adverse effect of pholcodine
Nausea
Drowsiness
Noscapine MOA
Depresses cough
No dependance
Same efficacy as codeine
Noscapine adverse effect
Headache
Nausea
Main use of noscapine
Spasmodic cough
Dextromethorphan MOA
No CNS depression
Dextromethorphan duration of action
6h
Can baladine inhibit Dextromethorphan
No because does not work through opioids receptors
Dextromethorphan side effects
Diziness
Nausea
Drowsiness
Ataxia
Levopropoxyphene
Non addicting
No opioid effect
Sedative property
Antihistamines MOA In cough
Non addicting antitussive
Relive cough by sedation and anticholinergic effect
Lack selectivity for cough center
When do you use antihistamine in cough
Allergic cough and may reduce secretion by anticholinergic action
Antihistamine most common
Diphenhydramine
Promethazine
Why are 2ndgen qntihkstamine not usd
Because cannot cross BBB so no sedative effect
Linctus
Thick liquid preparation with sucrose and medicinal substance
Sedative and demulcent properties
Throat lozenges
Small medicated tablets that dissolve slowly in mouth
Lubrication and soothing effect on throat
Fontaine benzocaine or Dextromethorphan
Bronchodilators
b2 agonist
Used when cough due to bronchospasm
Use of bronchodilators
Only when patient has bronchial hyperactivity
Example of bronchodilators
Salbutamol
Terbutaline
Benzonatate
Antitussive action on stretch or cough receptor in lungs
Central effects too
Benzonatate adverse effect
Headache Dizziness Pruritis Nasal congestion Burning of eyes Tightness In chest
Expectorant (bronchomucotropic/ mucokinetic agents)
Help relive secretion and exudate from trachea bronchi and lungs
Expectorants effect
Liquify biscuit mucus or mucopurulent exudate
Expectorant MOA
Direct acting -> stimulate secretory cells which dilute sputum and decrease irritation and viscosity of mucus
Indirect acting -> irritate gastric mucosa and increase respiratory tract fluid secretion and decrease viscosity of sputum
Expectorants names
Ipecacunha Ammonium chloride Ammonium bicarbonate Terepin hydrate Potassium iodide Guaiphenesin Sodium or potassium citrate
Ammonium salts expectorants
Gastric irritants which enhance bronchial secretion
Used in combinations with antitussive
Ipecacuanha actio
Expectorant at small doses
Emetic agent at late dose
Liquifies thick secretion
Used for emesis in accendital poisoning
Guaiphenesin MOA
Decrease sputum viscosity
Increase sputum volume
Decreas difficulty in expectoration
Use of guaiphenesin
Relief of dry non productive cough in presence of mucus
Adverse effect of guaiphenesin
Git disturbances
Drowsiness
Mucolytics
Render sputum less viscous so that more easily cleared
Mucolytics classification
Inhalation
Oral
Inhalational mucolytics
Acetylcysteine
Tyloxapol
Oral mucolytics
Acetylcysteine
Bromohexine
Carboxcysteine
Methylcysteine
Mucolytics MOA
Split disulfide bonds in mucoprotein in sputum
Reduced viscosity
Bromohexine clinical use
Acute and chronic bronchitis
Bronchial asthma
Bromohexine adverse effect
CNS headache tinnutis
GIT gastric irritation, disturbances
Skin : urticaria, rhinorrhea, lacrimation
