Antihistamines, Decongestants, etc

common cold

most caused by viral infection that invades the mucosa of upper respiratory tract; results in excessive mucus production → fluid drips down into lower respiratory tract causing cold sx: sore throat, coughing, upset stomach

treatment of the common cold

involves combined use of antihistamines, decongestants, antitussives, and expectorants; treatment is symptomatic only, not curative as it does not eliminate the causative pathogen; treatment is “empiric therapy”

antihistamines

drugs that directly compete with histamine for specific receptor sites; cannot knock histamine off, just blocks it; have several properties: antihistaminic, anticholinergic, sedative

anaphylaxis

release of excessive amounts of histamine can lead to: contraction of SM in stomach and lungs, increase in bodily secretions, vasodilation and increased capillary permeability → drop in BP and edema

histamine

major inflammatory mediator in many allergic disorders

H2 agonists/H2 blockers

used to reduce gastric acid in peptic ulcer disease; ex: cimetidine, famotidine, naztidine

antihistamines MOA

block action of histamine at H1 receptor sites (unoccupied receptors); the binding of H1 blockers to the receptors prevents the adverse consequences of histamine stimulation; more effective in preventing the actions of histamine rather than reversing them

antihistamine indications

management of: nasal allergies, hay fever, allergic reactions, motion sickness, parkinson’s, sleep disorders; also used to relieve symptoms associated with the common cold: sneezing, runny nose

antihistamine contraindications

narrow-angle glaucoma, cardiac disease, HTN, kidney disease, bronchial asthma, COPD, sole drug therapy for acute asthmatic attacks, PUD, seizure disorders, BPH, pregnancy

antihistamine AEs

anticholinergic drying effects most common; drowsiness

traditional antihistamines

older, work both peripherally and centrally (sedating effects); have anticholinergic effects, making them more effective than nonsedating drugs in some cases; ex: diphenhydramine

nonsedating antihistamines

work peripherally to block actions of histamine; thus fever CNS AEs; longer duration of action (increases compliance)

loratadine (claritin) & cetirizine (zyrtec)

nonsedating antihistamine drugs

antihistamine nursing implications

best tolerated when taken with meals to reduce GI upset; instruct pts to report excessive sedation, confusion, hypotension; avoid driving/operating heavy machinery; avoid alcohol/other CNS depressants; if dry mouth occurs perform frequent mouth care

decongestants

shrink enlarged nasal mucosal membranes → relieve congestion; three main types are used: adrenergics, anticholinergics, corticosteroids

oral decongestants

prolonged decongestant effects but delayed onset; less potent than topical; no rebound congestion; exclusively adrenergics; ex: psudoephedrine

topical adrenergic decongestants

prompt onset, potent, sustained use over several days causes rebound congestion; ex: ephedrine & phenylephrine

inhaled intranasal steroid and anticholinergic decongestants

not associated with rebound congestion; often use prophylactically to prevent nasal congestion in patients with chronic upper respiratory tract symptoms

fluticasone (flonase)

intranasal steroid

ipratropium

intranasal anticholinergic

decongestants indications

relief of nasal congestion associated with: acute or chronic rhinitis, common cold, sinusitis, hay fever, other allergies; may also be used to reduce swelling of the nasal passage and facilitate visualization of the nasal or pharyngeal membranes before surgery/diagnostic procedures

decongestants contraindications

narrow-angle glaucoma, uncontrolled cardiovascular disease, HTN, diabetes, hyperthyroidism, hx of CVA or transient ischemic attacks, long-standing asthma, BPH

nasal decongestant AEs

adrenergic: nervousness, insomnia, palpitations, tremors

steroids: local mucosal dryness and irritation

nasal decongestant interactions

systemic sympathomimetic drugs and sympathomimetic decongestants = drug toxicity; MAOI’s and sympathomimetic decongestants = increased BP

decongestants nursing implications

avoid caffine, report a fever, cough, or other sx lasting longer than 1 week

antitussives

drugs used to stop or reduce coughing; opioid and nonopioid; *used only for nonproductive coughs

opioid antitussives MOA

suppress the cough reflex by direct action on the cough center in the medulla; analgesia, drying effect on mucosa of respiratory tract, increased viscosity of respiratory secretions, reduction of runny nose and postnasal drip

nonopioid antitussives MOA

suppress the cough reflex in medulla, no analgesic properties & no CNS depression

codeine & hydrocodone

opioid antitussive drugs

benzonatate & dextromethorphan

nonopioid antitussive drugs

antitussive contraindications

opioid dependency & respiratory depression

antitussive AEs

benzonatate: dizziness, HA, sedation, nausea

dextromethorphan: dizziness, drowsiness, nausea

opioids: sedation, n/v, lightheadedness, constipation

expectorants

drugs that aid in the expectoration (removal) of mucus; reduce the viscosity of secretions; disintegrate and thin secretions; by loosening and thinning sputum and bronchial secretions, the tendency to cough is indirectly diminished

guaifenesin

expectorant drug

expectorants MOA

reflex stimulation: drug causes irritation of GI tract → loosening and thinning of respiratory tract secretions occur in response to this irritation; direct stimulation: the secretory glands are stimulated directly to increase their production of respiratory tract fluids

expectorants indications

used for the relief of productive coughs associated with: common cold, bronchitis, laryngitis, pharyngitis, coughs caused by chronic paranasal sinusitis, pertussis, influenza, measels