Drugs for Allergic Rhinitis Cough and ColdsPresentation Transcript
DRUGS FOR ALLERGIC RHINITIS, COUGH, AND COLDS Pharmacology Lab
Allergic rhinitis is an inflammatory disorder that affects the upper airway, lower airway, and eyes.
Symptoms are triggered by airborne allergens, which bind to IgE antibodies on mast cells and thereby cause release of inflammatory mediators, including histamine, leukotrienes, and prostaglandins.
Allergic rhinitis is the most common allergic disorder, affecting 15% to 20% of the U.S. population.
Oral antihistamines—H1-receptor antagonists most commonly prescribed for allergic rhinitis
do not decrease nasal congestion; no value for cold treatment
best when taken prophylactically, so administer on regular basis throughout allergy season
adverse effects mild, such as dry mouth, constipation, or urinary hesitancy (sedation with first-generation drugs such as diphenhydramine)
Azelastine nasal spray (Astelin)
Only antihistamine available for intranasal use via metered spray device
Bitter taste is common side effect
12% experience somnolence
Actions and uses—Most effective drugs for seasonal and perennial rhinitis; prevent or suppress major symptoms of allergic rhinitis; used for those that cannot be controlled with conventional drugs; may replace or join H1-receptor antagonists as first-line therapy
Intranasal Glucocorticoids: Continued
Adverse effects—Mild (drying of nasal mucosa and sensations of burning or itching); could get adrenocortical suppression
Preparations, dosage, and administration—Use metered spray device; give full doses initially then reduce to lowest effective dose; may need a week or more to develop benefits; maximum benefits in 2 to 3 weeks
Intranasal Cromolyn Sodium
Actions and uses—Safe and effective to relieve symptoms; no benefit for nonallergic rhinitis; acts on mast cells to suppress release of histamine and other mediators; take before onset of symptoms; takes about a week to develop beneficial effects
Intranasal Cromolyn Sodium: Continued
Dosage and administration (NasalCrom)—Administered with metered spray device; for children over 6 years and adults; one spray (5.2 mg) per nostril 4 to 6 times/day; use topical decongestant before cromolyn if nasal congestion present; use on regular schedule throughout allergy season
Actions and uses—Examples (phenylephrine) act by stimulating alpha1-adrenergic receptors on smooth muscle of nasal blood vessels vasoconstriction and decreased nasal drainage; topical administration is rapid and intense compared with oral decongestants
Sympathomimetics (Decongestants): Continued
Adverse Effects: Rebound congestion—Develops when topical decongestants are administered on regular basis for extended time; can become a cycle; need to discontinue drug or use in one nostril at a time or use no more than 3 to 5 days; not for chronic rhinitis
Cough is complex reflex involving CNS, peripheral nervous system, and muscles of respiration; should not suppress productive cough; otherwise, antitussive medication is appropriate
Suppress cough by acting within CNS or peripherally; two groups
Opioid antitussives—All opioid analgesics have ability to suppress cough; usually use codeine or hydrocodone, which act in CNS; hydrocodone more potent, so increased risk for abuse; codeine most effective to decrease frequency and intensity of cough; use 10 to 20 mg four to six times daily; not usually used for children
Dextromethorphan—Most effective; acts in CNS; a derivative of opioids; does not produce analgesia, euphoria, or physical dependence; usual dosage is 10 to 30 mg every 4 to 8 hours; adverse effects mild
Other nonopioid antitussives—Diphenhydramine can also suppress cough with sedative and anticholinergic properties; benzonatate is analogue of tetracaine and is thought to suppress cough by decreasing sensitivity of respiratory tract stretch receptors; mild adverse effects; swallow capsule intact
Expectorants and mucolytics
Expectorants make cough more productive; mucolytics make it more watery
Acute Upper Respiratory Infection
Of viral origin
fever common in children but rare in adults; no cure; treat symptoms
do not use antibacterial drugs unless a bacterial infection follows
no evidence that vitamin C prevents or helps cold
treat with drug for specific symptoms, not multiple mixtures for single symptoms
Upper Respiratory Infection
combination drugs usually include a nasal decongestant, an antitussive, an analgesic, an antihistamine, and caffeine
antihistamine only for its anticholinergic effect and caffeine to offset sedative effects of antihistamine
disadvantages include either over or undermedicating with one or more of the combinations
You are doing a clinical rotation in a family practice setting. You have been assigned to follow Ms. K through her visit to the primary care provider. As you complete your interview with Ms. K, she asks whether you can answer some questions.
She says, “I have a lot of stuffiness with my nose. I’m not sure whether I want to take anything for it because my friend told me that she started to take a medication that was a decongestant spray, and now she can’t stop taking it. Do you know anything about this?” How should you reply?
She then asks, “Can anything be done to prevent dependency on a decongestant spray?” How should you respond?
You can tell Ms. K that decongestants can be used to reduce nasal congestion. They work by causing the blood vessels of the nose to constrict, which results in shrinkage of the swollen nasal membranes. When nasal sprays are used for more than a few days, the effects of each application wear off, and the congestion becomes more severe. To overcome the rebound congestion, the patient must use progressively larger and more frequent doses. Hence a cycle can develop. To break the cycle, use of the decongestant can be discontinued abruptly. This is very uncomfortable for the patient. The discomfort can be lessened by discontinuing use of the drug in one nostril at a time.
You can tell Ms. K that rebound congestion can be minimized by use of topical agents for 3 to 5 days.
The principle drugs used to treat allergic rhinitis include:
What is the role of antihistamines in the treatment of the common cold?
Antihistamines are of no value against the common cold because they do not reduce nasal congestion.
What is the role of antihistamines in the treatment of allergic rhinitis?
They can relieve sneezing, rhinorrhea, and nasal itching. Antihistamines are most effective when taken prophylactically and less helpful when taken after symptoms have appeared. Therefore they should be administered on a regular basis throughout the allergy season, even when symptoms are absent.
What is the only antihistamine available for intranasal use?
How does cromolyn work?
Cromolyn reduces symptoms by suppressing the release of histamine and other inflammatory mediators from mast cells.
What drug is a monoclonal antibody that is directed against immunoglobulin E (IgE)
The two most frequently drugs used for cough suppression are?
What is the most effective nonopiod cough suppressant available?