Pharmacology Chapter 36- Antihistamines, Decongestants, Antitussives, and Expectorants

Adverse effects of Antihistamines

(more common with traditional) Sedation. Dizziness, confusion (especially with the elderly). Paradoxical excitability. GI- constipation, nausea. Anticholinergic effects. Thickened bronchial secretions.

Adverse effects of decongestants-

*PO*- tachycardia, hypertension, insomnia, palpitations. *Topical*- rebound congestion. *Steroids*- dryness (bloody nose, sore throat), systemic effects are most avoided with use of inhaler.

Mechanism of action- Nasal decongestants

*Site of action-* blood vessels surrounding nasal sinuses. *Adrenergics-* - activate alpha 1 receptors -> constrict small blood vessels -> tissues shrink -> increases drainage of secretions.

Two types of Antihistamines

*Traditional Antihistamines*- - older. - work peripherally and centrally. - strong anticholinergic properties. - cautious use for many clients: glaucoma, urinary retention/obstruction, GI blockage. - Example: diphenhydramine (Benadryl). *Non-sedating/peripherally acting Antihistamines*- - less adverse effects because it works peripherally and not centrally. - longer duration of action. - Examples: fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec).

Decongestants

*Two main categories-* - Adrenergics (sympathomimetics)- alpha 1: vasoconstriction. - Corticosteroids (topical, intranasal)- minimize inflammatory response. Three dosage forms- - oral - inhaled - topically applied to the nasal membranes

Examples of Adrenergics used for Decongestion

- *Phenylephrine (Neo-Synephrine)*: should only be used for a maximum of 3-5 days (can cause rebound congestion). Potent, immediate relief. Topical- spray/drop. - *Pseudoephedrine (Sudafed)*: oral. Systemic effects, long-term response. - *Naphazoline (Privine)*: used primarily for eye congestion. (Can have rebound eye congestion).

Topical Nasal Decongestants

- Adrenergics - Rapid onset - Potent effects - Can cause rebound nasal congestion - Example: phenylephrine (Neo-Synephrine)

Examples of Intranasal steroids

- Beclomethasone (Beconase AQ) - Budesonide (Rhinocort Aqua) - Flunisolide (Generic only) - Fluticasone propionate (Flonase) - Mometasone (Nasonex) - Triamcinolone (Nasocort AQ) Most effective long-term decongestant. Expect 2-3 weeks for full effect.

Inhaled nasal decongestants

- Intranasal steroids - Examples: beclomethasone dipropionate, flunisolide (Nasalide), fluticasone (Flonase).

Oral decongestants

- Prolonged effects - Less potent - No rebound congestion - Example: pseudoephedrine (Sudafed)

The nurse who is providing patient teaching about antihistamine use will include which information? (Select all that apply) A. Antihistamines are best tolerated when taken with meals. B. The patient can chew gum if he/she experiences dry mouth. C. Drowsiness is a frequent side effect of antihistamines. D. Over-the-counter medications are generally safe to use with antihistamines. E. The patient should avoid drinking alcoholic beverages while on these drugs.

A. Antihistamines are best tolerated when taken with meals. B. The patient can chew gum if he/she experiences dry mouth. C. Drowsiness is a frequent side effect of antihistamines. E. The patient should avoid drinking alcoholic beverages while on these drugs.

The nurse notes in a patient's medications history that the patient is taking benzonatate (Tessalon Perles) as needed. Based on this funding, the nurse interprets that the patient has which problem? A. Cough B. Seasonal allergies C. Chronic rhinitis D. Motion sickness

A. Cough

When assessing a patient who is to receive a decongestant, the nurse will recognize that a potential contraindication to this drug would be which condition? A. Glaucoma B. Fever C. Peptic ulcer disease D. Allergic rhinitis

A. Glaucoma

A patient asks the nurse about the newer antihistamines. He wants one that does not cause drowsiness. Which of these drugs is appropriate? A. Loratadine (Claritin) B. Diphenhydramine (Benadryl) C. Dimenhydrinate (Dramamine) D. Meclizine (Antivert)

A. Loratadine (Claritin)

Mechanism of action- Nasal steroids

Antiinflammatory Works to turn off the immune system cells involved in the inflammatory response.

The nurse is reviewing a patient's medication orders for prn (as necessary) medications that can be given to a patient who has bronchitis with a productive cough. Which drug will the nurse choose? A. An antitussive B. An expectorant C. An antihistamine D. A decongestant

B. An expectorant

A patient is asking about taking an antihistamine for springtime allergies. The nurse assesses for contraindications to antihistamine therapy. Which of these conditions, if present, would be a contraindication? (Select all that apply) A. Type 2 diabetes mellitus B. Benign prostatic hyperplasia C. Hyperthyroidism D. Narrow-angle glaucoma E. Asthma

B. Benign prostatic hyperplasia D. Narrow-angle glaucoma E. Asthma

Which drugs are considered first-line drugs for the treatment of nasal congestion? (Select all that apply) A. Antihistamines such as diphenhydramine. B. Decongestants such as naphazoline. C. Antitussives such as dextromethorphan. D. Expectorants such as guaifenesin. E. Inhaled corticosteroids such as beclomethasone.

B. Decongestants such as naphazoline. E. Inhaled corticosteroids such as beclomethasone.

The nurse is giving an antihistamine and will observe the patient for which side effects? (Select all that apply) A. Hypertension B. Dizziness C. "Hangover" effect D. Drowsiness E. Tachycardia F. Dry mouth

B. Dizziness C. "Hangover" effect D. Drowsiness F. Dry mouth

The nurse is administering an expectorant and will provide which teaching? A. Avoid fluids for 30 to 35 minutes after the dose. B. Drink extra fluids, unless contraindicated, to aid in expectoration of sputum. C. Avoid drinking or operating heavy machinery while taking this medication. D. Expect secretions to become thicker.

B. Drink extra fluids, unless contraindicated, to aid in expectoration of sputum.

The nurse knows that an antitussive cough medication would be the best choice for which patient? A. A patient with a productive cough. B. A patient with chronic paranasal sinusitis. C. A patient who has had recent abdominal surgery. D. A patient who has influenza.

C. A patient who has had recent abdominal surgery.

When giving decongestants, the nurse must remember that these drugs have alpha-adrenergic-stimulating effects that may result in which effect? A. Fever B. Bradycardia C. Hypertension D. CNS depression

C. Hypertension

Which outcome would the nurse recognize as a positive response to guaifenesin? A. Decreased wheezing B. Increase in respiratory rate C. Increase in sputum production D. Decreased use of accessory muscles for breathing

C. Increase in sputum production

When giving an antitussive, the nurse remembers that they are used primarily for what reason? A. To relieve nasal congestion. B. To thin secretions to ease removal of excessive secretions. C. To stop the cough reflex when the cough is nonproductive. D. To suppress productive and nonproductive coughs.

C. To stop the cough reflex when the cough is nonproductive.

Interactions with Antihistamines

CNS depressants Anticholinergics

A patient has been self-medicating with diphenhydramine (Benadryl) to help her sleep. She calls the clinic nurse to ask, "Why do I feel so tired during the day after I take this pill? I get a good night's sleep!" Which statement by the nurse is correct? A. "You are probably getting too much sleep." B. "You are taking too much of the drug." C. "This drug is not really meant to help people sleep." D. "This drug often causes a 'hangover effect' during the day after taking it."

D. "This drug often causes a 'hangover effect' during the day after taking it."

A patient is taking a decongestant to help reduce symptoms of a cold. The nurse will instruct the patient to observe for which possible symptom, which may indicate an adverse effect of this drug? A. Increased cough B. Dry mouth C. Slower heart rate D. Heart palpitations

D. Heart palpitations

Expectorants

Drugs that aid in the expectoration (coughing up and spitting out) of excessive mucus. - reduces the viscosity of secretions. - disintegrates and thins secretions. *Examples-* - Guaifenesin (Mucinex) - Acetylcysteine (Mucomyst)

Antihistamines

Drugs that directly compete with histamine for specific receptor sites. This chapter focuses on H1 blockers. *Mechanism of action*- - binds to histamine receptors and blocks histamine release from mast cells and basophils. - does not push off histamine already bound to a receptor; so it is best given early in an allergic reaction.

Nursing implications for Expectorants

Expectorants should be used with caution in the elderly, or those with asthma or respiratory insufficiency. Patient on expectorants should increase fluid intake (if not contraindicated). Report a fever, cough, or other symptoms lasting longer than a week. Monitor for therapeutic effects.

Nursing implications for Antihistamines

Gather data about the condition or allergic reaction that requires treatment. Assess for drug allergies. *Contraindications*- glaucoma, bowel/bladder obstruction, acute asthma. *Cautious use*- renal/hepatic function, elderly, peds, increased intraocular pressure, chronic obstructive pulmonary disease (COPD), benign prostatic hyperplasia (BPH), peptic ulcer disease (PUD). *Patient teaching*- - report excessive sedation, confusion. - avoid hazardous activities such as driving, operating machinery. - do not consume alcohol or other CNS depressants. - check with provider about OTCs. - tips to deal with dry mouth. Monitor for therapeutic effects- symptom control.

Two histamine receptors

H1 - arterioles, venules, bronchi. H2- GI.

Therapeutic uses of Antihistamines

Mild or severe allergy. Motion sickness, nausea. Insomnia. Common cold. Vertigo. Rash. Parkinson's disease.

benzonatate (Tessalon Perles)

Non-opioid antitussive. Decreases sensitivity to stretch receptors. Never crush or chew: can numb mouth and gag reflex. *Adverse effects*- sedation, dizziness.

dextromethorphan (Robitussin-DM)

Non-opioid antitussive. Suppresses cough reflex. Has become commonly abused. *Adverse effects*- dizziness, lightheadedness.

Codeine

Opioid Antitussive. Suppresses cough reflex. *Adverse effects*- constipation, N/V, respiratory depression, lightheadedness. Avoid other CNS depressants.

Nursing implications for Decongestants

Oral decongestants can cause the following (because of SNS stimulation): tachycardia, hypertension, palpitations, insomnia. Patients on antihypertensive medications must check with their provider before taking an oral decongestant, because it can make the HTN worse. Assess for drug allergies. Avoid caffeine. Report a fever, cough, or other symptoms lasting longer than a week. Monitor for therapeutic effects.

Nursing implications for Antitussives

Perform respiratory and cough assessment. Assess for allergies. Instruct patient to avoid driving or operating heavy equipment because of possible sedation, drowsiness, or dizziness. Avoid liquids for 30 minutes after taking a lozenge. Report any of the following symptoms to the caregiver- - cough that lasts more than a week. - persistent headache. - fever. - rash. Used for non-productive coughs only. Monitor for therapeutic effects.

Indications for use of Decongestants

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/pharyngeal membranes before surgery or diagnostic procedures.

Histamine

Substance present throughout the body. Can cause dilation, increased heart rate, increased GI secretions and capillary permeability.

Opioid Antitussives

Suppress the cough reflex by direct action on the cough center in the medulla. Examples- - *Codeine*: most effective cough suppressant available. - Hydrocodone.

Nonopioid Antitussives

Suppress the cough reflex by numbing the stretch receptors in the respiratory tract and preventing the cough reflex from being stimulated. *Examples-* - benzonatate (Tessalon Perles) - dextromethorphan (Robitussin-DM)

Examples of Antihistamines and Specific Nursing Implications

Traditional- *Diphenhydramine (Benadryl)-* give with food to decrease GI upset. Avoid alcohol. *Hydroxyzine (Vistaril)-* used for anxiety, pruritus, and mainly for pre-op sedation. Never give IV! *Promethazine (Phenergan)*- Black box alert: IV can cause gangrene; can cause respiratory depression in children (< 2 yrs old). Non-sedating/peripherally acting- *Cetirizine (Zyrtec)*- can give to kids 2 yrs of age and older. *Fexofenadine (Allegra)*- avoid apple, grapefruit, and orange juice, alcohol. *Loratadine (Claritin)*- can interact with amiodarone and increase QT interval (fatal dysrhythmia).

Antitussives

Used to stop/reduce cough. Only used for non-productive cough; or when when cough is harmful. Types: opioid and nonopioid