2 - Respiratory Pharmacology Flashcards
What are the 3 types of nasal decongestants?
- Direct alpha adrenergic stimulants
- Mixed function adrenergic stimulants
- Orally administered
What is the mechanism for direct alpha adrenergic stimulants?
- Vasocontriction to reduce edema
- Decrease bloodflow to tissues in nose, which decrease tissue volume, making it easier to breathe
What are the preparations of direct alpha adrenergic stimulants?
- Nasal spray
- Vasoconstrictors:
- propylhexedrine (Benzedrex - OTC)
- oxymetazoline (Afrin)
- tetrahydrozoline (Visine)
- naphazoline (“Clear Eyes”)
Why is Afrin limited use to only 3 days?
Addictive: it crosses the BBB
What is the side effects of direct alpha adrenergic stimulants?
- Increased peripheral resistance
- Bradycardia
- Rebound congestion with extended use
What is the mechanism of Mixed function adrenergic stimulants?
- Alpha and beta stimulation, direct and indirect effects (sympathomimetic)
What are the preparations of mixed function adrenergic stimulants?
-
ephedrine - releases tissue stores of epinephrine, thus stimulates alpha and beta receptors
- Crosses BBB and causes CNS excitation, bronchial dilation / relaxation
- phenylephrine (Neo-Synephrine)
What is the mechanism of orally administered direct-acting alpha and beta agonists (sympatheticomimetic)?
- Directly stimulates alpha receptors of respiratory mucosa causing vasoconstriction
- Directly stimulates beta receptors causing bronchial relaxation
- Works systemically, not locally
What is the common preparations of orally administered direct-acting alpha and beta agonists?
- pseudoephedrine (Sudafed, Actifed)
When a patient is taking decongestants, what must be given with caution and why?
- epinephrine (vasoconstrictor)
- These drugs are sympathomimetics and may enhance cardiac stimulation (tachycardia) and elevate blood pressure
What does the antigen-antibody response of bronchial asthma cause to be released?
- Histamine - vasodilation and edema, bronchoconstriction
- PGD2 - bronchoconstriction, inflammation
- LTC4/LTD4 - urticaria/angiodema, mucosal edema, smooth muscle spasm, attracts eosinophils
What are the main symptoms of bronchial asthma?
- Functional increase in airway resistance and decrease in lung compliance
- Inflammation, mucous secretions, spasm of airway
What are medications that can trigger asthma?
- Aspirin - bronchoconstriction in 10% of pts with asthma
- NSAIDS
- Antihypertensives - beta blockers, ACE inhibitors
- Sulfites (preservatives) - found in dental local anesthetics that contain epinephrine to prevent oxidation of vasoconstrictor
What is the basic principle behind using medications to treat asthma?
- Many beta adrenergic drugs block phosphodiesterase which increases tissue concentrations of cAMP
- Which promotes catecholamine stimulation and epinephrine release from adrenal medulla = this accounts for their cardiac side effects
- Increased cAMP in inlammatory cells decrease release of autocoids = desired effect
- Tradeoff: bronchodilation but with adverse cardiac events
What is the mechanism of epinephrine?
Increases cAMP in inflammatory cells which reduce autocoid release
How can the action of epinephrine be blocked?
By propranolol (Inderal), a non-selective beta blocker used as an antihypertensive
What is the important rescue drug for asthma?
Inhalers - reversal of airway obstruction and bronchoconstriction; acute treatment of bronchospasm “asthma attack”
What is the mechanism for inhalers?
Target beta 2 receptors in airway, resulting in bronchodilation
What are the short acting beta adrenergic stimulants (rescue drugs)?
- albuterol (Proventil, Ventolin) - in all dental office emergeny kits
- levalbuterol (Xopenex) - R enantiomer of albuterol
- metaproterenol (Alupent)
- pirbuterol (Maxair)
- terbutaline (Brethaire)
What are the long-acting beta adrenergice stimulants (maintenance/prevention)?
- salmeterol (Serevent Diskus) - duration to 12 hours
- salmeterol with fluticasone (steroid) (Advair Diskus)
What are some important dental considerations with inhalers?
- Taste alteration
- Oral candidiasis (with combined steriods)
- Overuse of inhalers can lead to a hyper reflexive airway
- Have pts bring inhalers with them
Why ask your patients about how often they are using their inhalers?
If its more than once daily or 2 days per week it suggests uncontrolled asthma = REFER
What type of drug are methylxanthines?
Beta Adrenergic Stimulants
Older class of asthma drugs that are now typically thought of as reserve drugs, used for patients for whom newer, better asthma meds are ineffective.
Why are xanthines considered “red flag” drugs?
- Cause dangerous drug interactions resulting in CNS stimulation and increased risk for seizures
- Antibiotics: macrolides
- Systemic (azole) antifungals - ketoconazole
What type of drugs block phosphodiesterase which increases cAMP?
Methylxanthines
What’s the preparations of methylxanthines?
- theophylline (Elixophyllin, Theochron, Theo-24)
What are the drugs of choice for reducing inflammation?
Steroids
What are steroids mechanism of action?
- Reduce cytokine production
- Inhibition of accumulation of basophils, eosinophils and leukocytes
What are dental considerations of steroids?
- Oral candidiasis
- Susceptibility to infection
- Delayed wound healing
- Adrenal suppression
What is acetylcysteine (Mucomyst) and what does it do?
Mucolytic
Exerts mucolytic action through its free sulhydryl group = opens up disulfide bonds in mucoproteins, thus lowering mucous viscosity
What drug is used for chronic bronchopulmonary diseases and cystic fibrosis?
Mucolytics - acetylcysteine (Mucomyst),
dornase alfa (Pulmozyme) just for CF
What drug is a DNA enzyme (recombinant) which cleaves DNA, reducing mucous viscosity?
dornase alfa (Pulmozyme) for cystic fibrosis
What are expectorants mechanism of action and what’s the common prep?
Irritation of stomach while stimulating respiratory fluid volume, decreases mucous viscosity
guaifenesin (Mucinex, Robitussin)
What type of drugs depress cough center in medulla?
Anti-tussive drugs
What is a common prep of an anti-tussive drug?
dextromethorphan (Delsym, Robitussin, Triaminic, Vicks 44)
Relative of morphine, lacking narcotic properties except in overdose
What type of drug is codeine?
D,L racemic mixture form of codeine will be anti-tussive, but also addictive, D form is less
Of the Leukotriene drugs, which drug inhibits the synthesis of leukotriens and which one blocks luekotriene receptors?
- zileutron (Zyflo) = inhibits synthesis
- zafirlukast (Accolate) & montelukast (Singulair) = blocks leukotriene receptors
What type of drugs are used for prevention of seasonal allergies and exercise-induced asthma? And what are the common preps?
Mast cell inhibitors
- cromolyn (Nasalcrom - OTC)
- nedocromil (Tilade) - inhaled only
What is the drug of choice for emphysema? And what’s it’s mechanism?
Anticholinergic medication
ipratropium (Atrovent)
Blocks action of acetylcholine at parasympathetic sites in bronchial smooth muscle causing bronchodilation
What’s the mechanism for respiratory depressants?
Decreases sensitivity to increased PCO2 levels and to hypoxic drive
Narcotics, barbiturates, ethanol overdose
What’s a common prep for a respiratory stimulant?
doxapram (Dopram)
