Antihistamines & Drugs for Allergy Flashcards
1st Generation Antihistamines
Diphenhydramine Dimenhydrinate Doxylamine Hydroxyzine Meclizine
CNS symptoms in >20% of pts
Avoid in small children and elderly! (anticholinergic effects)
Lipophilic (cross BBB)
AE: SEDATION and reduced awareness of sedation
2nd/3rd Generation Antihistamines
Loratadine Cetirizine Levocetirizine Fexofenadine Desloratidine Loratadine
Lipophobic - may have less CNS effects
Longer acting
Antihistamine Nasal Spray
Azelastine
Olopatidine
Anti-inflammatory & improve congestion
Less effective than intranasal glucocorticoids
Decongestants
Systemic: Cause irritability, HTN, insomnia, tachycardia, mydriasis
Intranasal: Use no more than 3 consecutive days! (will get rebound congestion)
Not for monotherapy in chronic treatment!
Apha 1 Selective agonists
Phenylephrine - used topically as nasal or ophthalmic decongestant
AE: rebound congestion w/use > 3 days
Nonselective Agonists (alpha and beta)
Pseudoephedrine
precursor in meth synthesis
Used orally as nasal decongestant
AE: mydriasis, dry mouth, HTN, tachycardia, insomnia, myocardial ischemia, anxiety
Decongestant Contraindications
Hypersensitivity Uncontrolled HTN Severe CAD With MAO-I Caution in children
Hydrocodone and Codeine (opioids)
Antitussives MOA: Block cough signal through medullary cough center RESPIRATORY DEPRESSION! Sedating, euphoric Addiction/dependence potential
Dextromethorphan (L-isomer of opioid)
MOA: Stops opioid-related sigma receptor mediated transmission of cough impulse
No euphoria/addiction potential
Metabolized by CYP2D6
RISK OF SEROTONIN SYNDROME
Benzonatate (non-opioid)
MOA: Reduces activity at peripheral cough receptors
VERY TOXIC in overdose!
Guaifenesin
Expectorant
MOA: Increases respiratory fluid secretion (decrease viscosity of mucus)
Adequate hydration may improve response
AE: nausea, headache
Corticosteroids
Used for asthma, COPD, allergic rhinitis
MOA: Block late-phase rxn to allergen, reduce airway hyperresponsiveness, inhibit inflammatory cell migration and activation
Most potent & effective anti-inflammatory meds
Intranasal Steroids
Onset: most are a few hrs, maximal effect may require several days or weeks in long-standing symptoms
1st Gen: 10-50% bioavailability (more systemic effects)
2nd Gen:
Leukotriene Antagonists
Generally 3rd line after intranasal steroid & oral antihistamines
MOA: block leukotrienes, which cause smooth muscle contraction & increased airway resistance
Mast Cell Stabilizers (release inhibitors)
Cromolyn Not bronchodilator but can prevent bronchoconstriction caused by challenge w/ antigen to which pt is allergic Not absorbed (only local effects) AE: cough and airway irritation Preventive treatment prior to exercise
