Antitussives (Maize) Flashcards
Cough Reflex
- coughing expel mucus, cellular debris and foreign material from the airways
- the sensory receptors send signals through the vagal afferent fibers to the central cough center in the medulla
- where do drugs work: sensory receptors (afferent) and cough center (motor)
Oral Antitussives
- Opiods Mu: codeine, hydrocodone (Hycodan, Codamine, Hycomine, Tussionex)
- Opiods Sigma: dextromethorphan (Robitussin & Delsym
- Nonopioids: benzonatate (Tessalon Perles)
- Antihistamines: diphenhydramine (Benadryl), promethazine (Phenergan), chlorpheniramine (Triaminic Allergy), and brompheniramine (Dimetane)
Mechanism of Action of Oral Antitussives
- Opioids: Mu AGONIST on medullary cough center and respiratory tract
- Dextromethorphan: Sigma AGONSIT on medullary cough center & N-methyl-D-aspartate (NMDA) ANTAGONIST on medullary cough center
- Antihistamines: H1 inverse agonist and muscarinic antagonsit on medullary cough center and respiratory tract
- Benzonatate: sodium channel blocker (won’t get the action potential to send afferent signal that will stimulate the cough center)
Pharmacological Effect of Oral Antitussives
- Opioid derivatives and Antihistamines: decreases the cough center, decreases the sensitivity of the sensory receptors in the respiratory tract and dries the respiratory tract
Non-opioid derivatives: anesthetizes the sensory receptors in the respiratory tract
Hydrocodone > codeine = (>) dextromethorphan > benzonatate
Side Effects of Oral Antitussives
- Codeine & hydrocodone (Mu):nausea, drowsiness to sedation, dizziness, constipation, high addiction and tolerance potential and analgesic activity
- Dextromethorphan (Sigma): nausea, drowsiness, dizziness, constipation, no analgesic activity, sedation, respiratory depression or addiction at therapeutic doses, and at extremely large doses produce intoxication with hallucinations
- Benzonatate: drowsiness, dizziness, headache, nasal congestion, a vague “chilly” feeling, don’t chew can choke b/c of numbing
- Diphenhydramine & promethazine (1st gen): sedation, anticholinergic effects
Topical Antitussives
Local Anesthetics:
Vicks VapoRub, VapoSteam (camphor & menthol
Halls cough drops (menthol)
Vicks cough drops (menthol)
Cepacol Maximum Strength (benzocaine)
Chloraseptic (benzocaine)
Robitussin cough drops (menthol & eucalyptus oil)
Cepastat Maximum Strength (phenol, menthol & eucalyptus oil)
Sucrets (dyclonine hcl)
Demulcents (coats throat from irritation):
Pectin (Luden’s, Halls)
Glycerin (Ricola)
Honey
Syrup
Mechanism of Action of Antitussives
- Local anesthetics effect of AROMATIC VAPORS- block Na channels at sensory receptors
- demulcents: coats and relieves irritation of throat
- placebo effect: mom’s touch
Side effects of topical antitussives
irritation, redness or blistering of skin
Toxicity of topical antitussives
- 2 g dose of menthol can be fatal
- concentrations greater than 10% of camphor can produce seizures
- 4 teaspoons of 5% camphor can be lethal in children
Mechanism of Action of Expectorate
- increases mucocilliary transport
- increases the volume of pulmonary secretions by diluting mucus
Side Effects of Expectorate
N/V, dizziness, headache and rash
Mucolytics
Products: Acetylcysteine (Muscomyst, Mucosil and an antidote), DNAse (dornase alfa) Pulmozyme, Water
Uses: cystic fibrosis and APAP toxicity
Mechanism of Action of Mucolytics
Acetylcysteine: free sulfahydryl groups reduce the disulfide bonds (rotten egg smell) of the mucoproteins and they break apart
DNAse: DNA enzyme, purulent/thick mucus is composed of highly polymerized DNA, Dornase selectively cleaves DNA thus reducing mucus viscosity
Water: thins mucus by dilution
Side Effects of Mucolytics
Acetylcysteine: nausea, vomiting, severe rhinorrhea, drowsiness, and rare hypersensitivity
DNAse: cough, fever, rhinorrhea, voice alteration
