Antitussives and Mucolytics Flashcards Preview

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Flashcards in Antitussives and Mucolytics Deck (24):

What are the causes of cough that we must determine before prescribing an antitussive (anti-cough medicine)?

- chronic bronchitis
- postnasal drip (sinusitis)= antibiotics, decongestants (anticholinergics), or H1-blockers.
- postnasal drip (allergy)= inhaled corticosteroids


When are antitussives appropriate?

when cough is NON-PRODUCTIVE!!


What is the goal of therapy for a productive cough?

increase volume and decrease viscosity of mucus in order to eliminate it.


What do expectorants do?

reduce adhesiveness and surface tension of mucus, and thin bronchial secretions. These actions loosen phlegm, enhance removal of viscous mucus, and increase output of respiratory tract fluid.


**** What antitussives are available for non-productive coughs?

1. Guaifenesin (robitussin)
2. potassium iodide= accumulates in thyroid gland, gastric juice and saliva. Not widely used due to ADRs (lesions of small bowel, hypothyroidism, iodine poisoning, excreted in breast milk...)
3. iodinated glycerol= similar to potassium iodide, but contains 22% alcohol and contraindicated in pregnancy.
4. terpin hydrate= derived from oil of turpentine, thyme, and eucalyptus, but contatins 42% alcohol and can cause fetal alcohol syndrome.


What are the contraindications for potassium iodide?

- impaired renal function
- acute dehydration
- hyperthyroidism
- reacts with lithium (increasing lithium's concentration)


**** What drugs can increase the clearance of mucus?

1. theophylline= bronchodilator via relaxation of bronchial smooth muscle and pulmonary blood vessels, but stimulates CNS.
2. beta 2-adrenergic agonists (albuterol)= bronchodilator


**** What are some drugs given to decrease AFFERENT input (sensory stimuli carried by vegus to medulla) for local anesthetics?

- lidocaine (topical= short acting, or IV= for persistent cough after general anesthesia + bronchoscopy).
- benzonatate= anesthetizes stretch receptors in respiratory tract. Capsule must be swallowed whole; NOT chewed.


** What are the ADRs of benzonatate?

- chest numbness, pruritus, skin eruptions
*overdose actually causes CNS stimulation followed by CNS depression. Keep out of reach of children bc this can cause death in accidental ingestion in children less than 10.


When can NSAIDs be helpful for cough?

for non-productive cough caused by ACE inhibitors, which incidentally increase prostaglandins, and the action of NSAIDs decreases prostaglandins :)


What narcotic is the primary antitussive drug?

- CODEINE (antitussive dose is less than analgesic dose). It acts by depressing the cough reflex and will dry mucosal secretions and extensively biotransform to MORPHINE!


What must you be aware of in pts with asthma and pulmonary emphysema when using codeine as an antitussive?

- can severely reduce respiratory reserve, and will increase the viscosity of bronchial secretions). Therefore prescribe Guaifenesin with this to decrease the viscosity.
- may prolong labor
- do NOT use any opioid in premature infants


*** What has the FDA said about use of codeine after tonsilectomy or adenoidectomy?

DO NOT USE, bc some children may have been rapid metabolizers of codeine leading to overdose of morphine (due to cytochrome P450 2D6).


Can you combine codeine with antihistamines for cough suppression?

YES, but be careful due to CNS depression, constipation, and orthostatic hypotension.


What is hydrocodone + chlorpheniramine?

semisynthetic opioid (similar to codeine) with antitussive and analgesic actions. This is an ER suspension (solution with undissolved particles).


What is dextromethorphan?

NMDA blocking agent that is a non-narcotic that is an isomer of codeine analog of levorphanol. Less potent than codeine but is an abused substance.
*do not take with MAO inhibitors


What is diphenhydramine (benadryl)?

- antihistamine with significant sedative, anticholinergic, and antiemetic effects. This is used only for symptom management only.
*drying effect of respiratory secretions can cause obstruction.


**** What is an antitussive that decreases the EFFERENT limb?

- ipratropium= anticholinergic given by inhaler to block M-sites resulting in bronchodilation


**** What are some antitussives that decrease the respiratory muscles?

nondepolarizing skeletal muscle relaxants for pts on ventilators who develop coughing spasms:
- pancuronium
- vecuronium


**** What is acetylcysteine?

- MUCOLYTIC agent that splits disulfide bonds and causing depolymerization to decrease the viscosity of mucus.
- adjuvant therapy in CHRONIC bronchopulmonary disease (emphysema and TB).
- also used in ACUTE bronchopulmonary disease (bronchitis, pneumonia...)
*treats acetaminophen overdose!!!


How is acetylcysteine administered?

via nebulizer (drug delivery device used to administer medication in the form of a mist)


How is most of acetylcystein metabolized?

hepatic (70%)


What is considered acetaminophen overdose?

3000 mg!
*so be aware if you prescribe narcotics that have acetaminophen in the them (aka percocet) not to take too much acetaminophen additionally.


**** How is acetaminophen metabolized?

4% is biotransformed to acetimidoquinone (a toxic metabolite) that is detoxified by conjugation with hepatic GLUTATHIONE (thus using up protective glutathione in the body).