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Drug Classes & Actions : Antihistamines Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Commonly Prescribed For...

Allergic Rhinitis
Hay Fever
Insomnia
Nasal Congestion
Anaphy­laxis
Urticaria
Motion Sickness
Angioedema
Drug Fevers
Parkin­son­-like Reactions

Indica­tions

Allergy Symptoms
Sedative
Antich­oli­ner­gic­-Pr­ope­rties: Antihi­sta­mines effect the secretions of the lacrimal, salivary, and respir­atory mucosal glands.

What is Histamine?

Released By: mast cells, basophils, and other cells in response to antigens circul­ating in the blood.
Mechanism Of Action: bind to/act­ivate cells in the nose, eyes, respir­atory tract, GI tract, and skin, producing charac­ter­istic allergic S&S

MOA - Receptor Antagonist & Inverse Agonist

H Receptor Antagonist: Competes with histamine at the unoccupied H receptor sites of basophil and mast cells in the smooth muscle surrou­nding blood vessels and bronch­ioles.
Inverse H Receptor Agonist: Binds to the H receptors and instead of taking up the space, induce the opposite effect of a histamine.
First Generation: Strong sedative effect, can increase the effect of opiods analgesics and some non-opiod analge­sics. Can be used as an analgesic itself in some cases (orphe­nad­rine)
Second Generation: Less likely to cause adverse effects on the heart, central nervous system and other organs than first generation antihi­sta­mines. Have a less sedative effect because they cross the blood-­brain barrier slower and act mainly on peripheral receptors. Have a longer duration of action.
Third Genera­tion: Stimulant and nootropic effects.
Fourth Generation: Immuno­mod­ulatory effects
NOTE: Antihi­sta­mines do not block histamine release, antibody produc­tion, or antige­n-a­ntibody reactions. They also don't push off histamines from receptor sites.

Generic & Trade Names

Generic
Trade
Route
Periph­erally Acting
Loratadine
Claritin
Tablet (10mg), Soft Gel Capsule (10mg), Syrup (1mg/ml)
Cetirizine Hydroc­hloride
Fexofe­nadine Hydroc­hloride
Tradit­ional
Diphen­hyd­ramine Hydroc­hloride
Aller-­Aide®, Allernix®, Benadryl®, others
caplets, capsules, chewable tablets, liquid, injection, spray, creams, lotions

Name Endings

-astine
Antihi­sta­minics
-azoline
Antihi­sta­minic, local vasoco­nst­rictor
-rizin­e/i­zin­e/yzine
Antihi­sta­minic, periph­era­l/c­erebral vasodi­lator
-tadine
H1-rec­eptor antago­nists, tricyclic compounds
-tidine
H2-rec­eptor antago­nists, cimetidine deriva­tives
 

Precau­tions & Contra­ind­ictions

Impaired Kidney Function
Pyloric Obstru­ction
BPH
Severe Liver Disease
Prostatic Hypert­rophy
Children <6yrs
Peptic Ulcer Disease
Hypers­ens­itivity
Pregnancy
Cardio­vas­cular Disease
Seizure Disorders
Hypert­hyr­oidism
Pulmonary Disease (COPD)
Angle-­Closure Glaucoma

Intera­ctions

Intera­ctions
Increases
Decreases
MAO Inhibitors
Antich­oli­nergic Properties
CNS Depres­sants
Sedation Effects
CNS Depres­sants: Alcohol, antide­pre­ssants, opiod analge­sics, sedatives & hypnotics

Side Effects

Cardio­vas­cular
Dysrhy­thmia
Palpations
Syncope
Hypote­nsion
CNS
Parado­xical Excitement
Sedation
Nervou­sness
Dizziness
Muscular Weakness
Restle­ssness
Seizures
Gastro­int­estinal
Nausea & Vomiting
Hepatitis
Diarrhea
Consti­pation
Other
Visual Distur­bances
Xerostomia
Tinnitus
Vertigo
Dry Nose & Throat
Headache
Urinary Retention

Assess­ments

Nausea & Vomiting: Assess the degree and frequency of nausea and the amount of emesis when admini­stering for nausea and vomiting
Anxiety: Assess mental status, mood, and behavior when admini­stering for anxiety.
Pruritus: Observe character, location, and size of affected area when admini­stering for pruritis skin condit­ions.
Respir­atory: Assess lung sounds for bronchial secret­ions. Maintain fluid intake (1500-­200­ml/day) to decrease viscosity secret­ions.
Allergy Symptoms: Assess for this before and period­ically throughout treatment.
IV Therapy: Assess BP and RR before and throughout IV therapy.

Nursing Diagnosis

Ineffe­ctive Airway Clearence
Indica­tions
Risk for Injury
Adverse Reactions
Deficiet Knowledge (Disease Proces­s/M­edi­cation Regimen)
Patien­t/F­amily Teaching

Implem­ent­ation

Prophy­laxis of Motion Sickness: Administer 30min-2hrs before exposure to motion sickness inducing condit­ions.
Concurrent Use w/ Opiod Analgesics: Supervise ambulation to prevent injury secondary to increased sedation.

Patient Education

Drowsiness: Inform patient they may feel drowsy. Avoid driving and activities requiring alertness.
Sedation: Caution patient to avoid concurrent use of alcohol or CNS depres­sants.
Xerostomia: Advise patient good oral hygiene, frequent mouth rinsing with water, and sugarless gum/candy may relieve from mouth dryness
Persistent Symptoms: Inform patient to contact a health care profes­sional if symptoms persist.

Evalua­tio­n/D­esired Outcomes

Decrea­se/­Prevent nausea
Decrease allergic S&S
Decrea­se/­Prevent vomiting
Relieve pruritus
Sedation when used as a hypnotic
Decrease anxiety

Additional Notes

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References

Lilley, L.L, Collins, S.R., Snyder, J.S., & Swart, B. (2017). Pharma­cology for Canadian Health Care Practice (2nd Canadian ed.). Toronto: Elsevier Canada.
Vallerand, A.H., & Sanoski, C.A. (2018). Davis’s Canadian Drug Guide for Nurses (16th ed.). Philad­elphia: F.A. Davis.
World Health Organi­zation, WHO. WHO Stembook 2013: The use of stems in the selection of Intern­ational Nonpro­pri­etary Names (INN) for pharma­ceu­tical substa­nces. 2013 [cited 22 Dec 2018]. Available from: https:­//w­ww.w­ho.in­t/m­edi­cin­es/­ser­vic­es/­inn­/St­emB­ook­_20­13_­Fin­al.pdf