Antihistamines Antacids Uri Meds

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Antihistamines

Chapter 69


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Outcomes

Identify concepts related to medication classificationsand application to manage allergic reactions,conditions of the upper respiratory system, acid

indigestion and gastric reflux. Choose nursing interventions related to the applied

pharmacokinetics and pharmacodyanmics specific tothese medications

Implement the nursing process in the administrationof medication classes covered herein


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Background

Histamines (Predominantly H1)

Endogenous

Vessel effects

Bronchi effects

Stomach effects

Secretes Mucus

Greatest interest Allergic reactions (mild / anaphylaxis)

PUD (Peptic Ulcer Disease)


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Histamine Release

Allergic response

Requires IgE antibodies

Prior exposure to allergen

Non-allergic direct stimulation of cells

Some drugs, chemicals, radiocontrast media,plasma expanders - require no prior exposure

Cell injury (histamines can cause)


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Physio / Pharm Effects

H1 Stimulation Vasodilation (If this, then?) BP drops, nose gets stuffy,

edema, puffy eyes, etc.

Vessel wall cells contract (If this, then?)

Bronchoconstriction (If this, then?) Trouble breathing

Itching & pain

Mucus secretion

CNS effect cognition / memory / sleep

H2 Stimulation Secretion of gastric acid (If this, then?)


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Allergies & Pharmacology

Mild Allergy Hay fever, urticaria, mild transfusion rx.

Sxms caused by? histamines

TX?

Severe Anaphylactic shock (bronchocontriction,

hypotension, & edema of glottis) Sxms caused by? leukotrienes

TX? (ch 17) Epi

Other Uses Common cold runny nose


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Antihistamines: 1st Generation

H1 Antagonists (classic antihistamines)

No single prototype

dyphenhydramine [Benadryl]

Highly sedating

MOA

Blockers (1st Gen)

Selectively bind to histaminic receptors

Can also bind to nonhistaminic receptor(muscarinic)


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Therapeutic Effects (TE) Vessels (If blocks histamine, then ?)

Capillaries (If blocks, then ?)

Sensory nerves (If, then) itching relief Mucous membranes (If, then)

CNS

Therapeutic doses (If, then) - sedation Overdose stimulation, seizures esp. in young

Other: relieve N & V, motion sickness


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Clinical uses Mild allergies, seasonal rhinitis, acute

urticaria, allergic conjunctivitis, mild

transfusion reactions Some block muscarinic & H1 receptor sites

useful for motion sickness promethazine [Phenergan] and dimenhydrinate

[Dramamine] Insomnia (diphenhydramine [Benadryl])


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Adverse Effects

CNS

Sedation = to excess ETOH (If this, then?)

Dizziness, lack of coordination, confusion

Paradoxical: insomnia, excitation, tremors,convulsions

GI N, V, Diarrhea / constipation, loss of appetite


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Anticholinergic effects Dry mouth, throat, nasal passages, thickened secretions,

(cautions?) urinary hesitancy, constipation, palpitations

Cardiac Dysrhythmias w some 2nd

Gen. Torsades de pointes, V-fib terfenadine [Seldane] & astemizole [Hismanal]

Contraindications third trimester

Precautions: asthma, children/elderly, urinaryretention, HTN, OA glaucoma, prostatichypertrophy


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D D

ETOH, barbs/benzos/ opioids, antidepressants

Toxicity

Sxms similar to atropine poisoning (anticholinergic),hyperpyrexia (super fever, can kill children)

Can lead to death in children via excitation,hallucinations, convulsion, coma, CV collapse, death.

Tx: remove and support may use charcoal followedwith cathartics


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Antihistamines: 2nd Generation

Prototypes - Fexofenadine [Allegra] -EXPENSIVE

MOA / TE antagonists of histamine to

relieve sxms of allergic rhinitis andurticarias ADME - Do not readily cross B-B barrier

therefore non-sedating w minimized

anticholinergic SEs Precautions ETOH, drowsiness, liver,

kidneys


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Drugs for Treating Allergic

Rhinitis, Coughs, Colds

Ch 75


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Allergic Rhinitis

Review of sxms

Commonly associated disorders

Seasonal vs. Perennial


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Antihistamines

First line - oral

Prophylaxis first

No use against cold Adverse effects

1st gen - sedation, anticholinergic

2nd

gen - rare


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Intranasal Glucocorticoids

Prototype: fluticasone (Flonase)

Action / Use Predominantly local anti-inflammatory

First line - Most effective against all sxms Adverse Effects

Drying, burning, or itching (when applied topically)

Rare - sore throat, epistaxis and HA

Rare - systemic adrenal suppression / slowedgrowth in children

Dose: Adults 2 sprays of 50 mcg. once daily


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Intranasal Cromolyn

Prototype: cromolyn (NasalCrom)

Action / Use

Suppresses release of histamine

Best suited for prophylaxis

May not see results for week or more

Adverse effects

Negligible


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Sympathomimetics (fight or flight)(Decongestants)

Prototype: phenylephrine (Neo-Synephrine) Action / Uses - Reduce nasal congestion via ?

Topical - rapid and intense Oral - prolonged, moderate, systemic effects

Also used in sinusitis and colds

Adverse effects Rebound congestion CNS stimulation

Cardiovascular Hemorrhagic stroke w phenylporpanolamine Abuse (pseudoephedrine and ephedrine)


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Sympathamometics (contd)

Nasal sprays

2 3 sprays every 4 hours needed not toexceed 5 consecutive days (to reduce

dependence)

What cocaine is


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Anticholinergics

Prototype: ipratropium bromide (Atrovent)

Action / Use

Blocks cholinergic receptors and inhibitssecretions to relieve rhinorrea in allergicrhinitis and asthma

No systemic effects

SEs: drying, irritation Dry mouth, throat, etc.


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Leukotriene Antagonist

Prototype: montelukast (Singulair)

Action / Uses;

Blocks binding of leukotrienes to receptorsthereby relieving nasal congestion

Leukotrienes normally vasodilate and increasevascular permeability, causing congestion

Adverse Effects: None significant Table 75-1 in book


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Treatment of Coughs


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Antitussives

Antitussives (cough suppressants)

Actions / use: elevate cough threshold incommon cold and URTI

Opioid (codeine and hydrocodone) best (stopscough in the brain)

Dosage: codeine 10 to 20 mg up to 6 times daily

Nonopioid (dextromethorphan) - best

Opioid derivative w/o euphoria or dependence

Can lead to mind-body dissociation equal to PCP


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Expectorants

Prototype - guaifenesin (Mucinex) MOA / Use increases flow of respiratory tract

secretions

Dont use for COPD or something else readthe friggin book


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Mucolytics

Prototype acetylcysteine (Mucomyst)

Can also use hypertonic saline

MOA / Use directly thins secretions

ADME

Inhalation delivery

Adverse effects Can trigger bronchospasm

Antidote for tylenol!


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Colds

Drug regimen

Symptomatic

Combination products

Decongestants

Antitussives

Analgesics

Antihistamines - anticholinergic to suppress mucus Caffeine


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Treatment of Severe Allergy

Chapter 17


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Adrenergic Agonist

Prototype - epinephrine

MOA/Use

Direct receptor binding ( 1&2, 1&2) mimicing the

sympathetic nervous system Also known as sympathomimetic & catecholamine (think of

these to mean stimulation)

ADME

Broken down quickly in stomach & significant 1st passeffect (cant take it PO)

Cant cross blood-brain

Discolors (pink/brownish) as it degrades (If, then?)

(Throw it away!)


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TEs (Therapeutic Effects) Vasoconstriction (most common use)

Hemostasis Augments local anesthetic via vascontriction Elevates blood pressure

Restores beating heart Bronchodilates

TOC for anaphylactic shock Mydriasis (rare use)

Adverse effects: HTN, necrosis, bradycardia w HTN, tachycardia,

tremor, chest pain, elevated blood sugar


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Table 17-3

D D MAOIs

TCAs

General anesthestics (myocardial effects)

Precautions

IV admin can cause potentially fatal effect

check concentrations! Insure patent and healthy IV site (you dont

want epi going into the tissuesThe range can be from 1:100,000 to 1:1,000 make sure to read the

label!!!!


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EpiPen

Anaphylactic deaths

PCN, venoms & foods

Device: EpiPen & EpiPen Jr.

Storage & Replacement Room temp dark do NOT refrigerate

Injection

Duration 10-20 mins SEs


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Selected Drugs for

Peptic Ulcer Disease (PUD)Chapter 76


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Histamine2-Receptor Antagonists

Prototype: cimetadine (Tagamet) First choice for gastric / duodenal ulcers

Action / Uses:

Promote healing through acid reduction

GERD, Aspiration Pneumonitis (aspiration of acid in the lungs) inobese & gyne prior to anesthesia

Adverse effects Low incidence of gynecomastia (breasts devlpmnt in men),

reduced libido, impotence, CNS depression / excitement,pneumonia

D D Inhibits hepatic drug metabolism therefore?

Major Drugs of concern warfarin, phenytoin, theophylline,lidocaine


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Famotidine (Pepsid)

For Heartburn, acid indigestion, sourstomach

Cut dose in renal compromise/failure

No antiandrogenic effects

No effect on hepatic metabolism of otherdrugs

Doesnt cause a lot of the things that Tagamet

does

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Proton Pump Inhibitors

Prototype - omeprazole (Prilosec)

Action / Uses suppress secretion of gastric acid Irreversible - days - up to weeks after cessation

Superior to H2RAs

Adverse effects HA, diarrhea, N & V

Long term may increase risk of CA

ADME give 30 min before meal once daily

D

D, D

F Reduced absorption of atazanavir, ketocanazole anditracanazole NOT recommended concurrently with atazanavir


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Antacids

Prototypes - magnesium hydroxide / aluminumhydroxide

Action / Uses alkaline agents that neutralizeacid & decrease destruction of gut wall And prophylactically to prevent aspiration pneumonia

ADME Take regularly to promote healing

In PUD: 1 and 3 hr after each meal & at bedtime Goal is gastric pH greater than 5


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Adverse effects

Constipation (aluminum base) / Diarrhea(magnesium base)

Sodium loading

High levels in renal failure clients

DD may interfere with absorption of

other drugs

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