PHARMACOLOGY - Drugs acting on Integumentary system

Information about Pharmacology

1. unit 7
drugs used in
treatment of
integumentary
disorders

2. antihistamine and antipruritics

3. Antihistamineisusedforthetreatmentofallergies.Drugsthat
inhibititchingarecalledantipruriticdrugs.Theyareavailable
informoftopicalpreparationlikecreamsandsprays.

4. AntihistaminicDrugs
Antihistaminesareaclassofmedicationsusedtotreathistamine-
mediateddiseases.Histaminereceptorsare:
❖Classifiedintotwotypes:H-1receptorsandH-2receptors.
❖Ingeneral,antihistaminesthatbindtoH-1receptorsareusedtotreat
allergiesandallergicrhinitis.
❖H-2receptoragonistshelptreatuppergastrointestinaldisorders
causedbyincreasedstomachacid.

5. Classification/Dose/Route of Antihistaminic Drugs
First Generation Antihistaminics
Highly Sedative
❑Diphenhydramine (Oral/IM/IV)
Foradultsandchildrenover12yearsold:Theusualoraldosefor
diphenhydramineis25to50mgevery4to6hours,nottoexceed300mg
perday.Forchildrenunder12yearsold:Theusualpediatricdosefor
diphenhydramineis1to2mg/kgevery4to6hours,withamaximumdaily
doseof300mg.

6. ❑Promethazine (Oral/IV/IM)
Foradultsandchildrenover12yearsofage,theusualdoseof
promethazineforallergiesis25mgtakenorally,2to3timesaday.

7. Moderately Sedative
❑Pheniramine (Oral/IV/IM/Rectal/Opthalmic)
•Theusualadultdoseforpheniramineis25mgto50mgtakenorally
every4to6hoursasneeded,withamaximumdailydoseof150mg.
❑Cyproheptadine (Oral/IM/IV/Topical)
•Thetypicaladultdoseofcyproheptadineforallergicreactionsis4mg
to20mgperday,dividedinto2-4doses,takenorally.

8. ❖Cinnarizine (Oral/Topical)
Thetypicaladultdoseofcinnarizineforoff-labelallergytreatmentis25
mgtakenonceortwicedaily.It'simportanttonotethatcinnarizineis
notafirst-linetreatmentforallergiesandshouldonlybeusedunderthe
guidanceofahealthcareprofessional.

9. Mild Sedatives
❑Chlorpheniramine (Oral/IM/IV)
Foradultsandchildrenover12yearsofage,thetypicalrecommended
doseofchlorpheniramineis4mgto8mgevery4to6hours,notto
exceed32mgperday.
❑Cyclizine (Oral)
Inrarecases,cyclizinemaybeusedoff-labeltotreatitchingorhives
causedbyanallergicreactionorotherskinconditions.Therecommended
doseofcyclizinefortreatingitchingorhiveswilldependonthe
individual'sage,weight,andtheseverityoftheirsymptoms.
❑Clemastine(Oral/IM/IV)
Therecommendeddoseofclemastineforadultsisusually1.34mg(2
tabletsof0.67mg)every12hours.

10. Second Generation Antihistaminic
❑Terfenadine (Oral): 60 mg twice daily.
❑Fexofenadine (Oral): The recommended dose of fexofenadine for
adults is 180 mg once daily.
❑Astemizole(Oral): 10 mg once daily.
❑Loratadine (Oral): The usual recommended dose of loratadine for
adults and children over 12 years old is 10 mg once daily,
❑Desloratidine(Oral): For adults and children 12 years of age and
older the recommended dose is 5 mg once a day.
❑Cetrizine(Oral): For adults and children over 12 years of age, the
usual recommended oral dose of cetirizine is 10 mg once daily.

11. Mechanism of
Action
H-1 Antihistamines
Histamine(anendogenouschemical
messenger)inducesanincreasedlevelof
vascularpermeability,whichleadstofluid
movingfromcapillariesintothe
surroundingtissues.Theoveralloutcome
ofthisisincreasedswellinganddilationof
vessels.Antihistaminesstopthiseffectby
actingasantagonistsattheH-1receptors.
Theclinicalbenefitisareductionin
allergysymptomsandanyrelated
symptoms.

13. Antiallergic Action
ImmediatehypersensitivitysuppressedinTypeIhypersensitivitywhich
havesymptomslikeurticaria,angioedema,itching.
H-2 Antihistamines
WhenhistaminebindstotheH-2receptorsonparietalcells,cyclic
adenosinemonophosphate(cAMP)increases,inducingproteinkinaseA.
Thisactionthenleadstophosphorylationoftheproteinsthattakepartin
thetransportofhydrogenions.Thusincreasedhistamineleadsto
increasedstomachacid,e.g.,HClsecretion.
TheuseofantihistaminesspecifictotheH-2receptorblockstheentire
processandreducesstomachacidsecretion.

14. Indications
H-1 Antihistamines
❖Allergic rhinitis
❖Allergic conjunctivitis
❖Allergic dermatological reaction(s)
❖Sinusitis
❖Urticaria
❖Angioedema

15. H-2 Antihistamines
❖Peptic ulcer
❖Acid reflux
❖Gastritis
❖Zollinger Ellison syndrome

16. SideEffectsandToxicity
❖Sedation,diminishedalertnessandconcentration,lightheadedness,
motorincoordination,fatigue,andtendencytofallasleep,impairment
ofpsychomotorperformance.
❖Anticholinergiceffects,epigastricdistressandheadache,contact
dermatitis,cautioninpregnancy.

17. ANTIPRURITICS
Antipruritics,alsoknownasanti-itchdrugs,aremedicationsthatinhibit
theitchingthatisoftenassociatedwithsunburns,allergicreactions,
eczema,psoriasis,chickenpox,fungalinfections,insectbitesetc.

18. MechanismofAction
Theexactmechanismofactiondependsonthetypeofantipruriticdrugused.
Herearesomeexamplesofhowantipruriticdrugswork.
•TopicalCorticosteroids
Thesemedicationsworkbyreducinginflammationandsuppressingthe
immuneresponse.Theyhelptoreduceitchingbyreducingtheinflammation
thatcancauseit.
•Antihistamines
Thesemedicationsworkbyblockingtheactionofhistamine,achemicalthatis
releasedbycellsinresponsetoanallergicreaction.Histaminecausesitching
andotherallergysymptoms,soblockingitsactioncanhelpreduceitching.
•OpioidAgonists
Thesemedicationsworkbybindingtoopioidreceptorsinbrainandspinal
cord,reducingtheperceptionofpainanditching.Theycanbeusedtotreat
severeitchingassociatedwithconditionssuchascancer,kidneydisease,or
liverdisease.

19. INDICATIONS
Skin conditions
(Eczema,
psoriasis, and
dermatitis etc.)
Allergic reactions.
Insect bites and
stings.
Infections
(Certain
infections, such as
chickenpox, can
cause itching)

20. Contraindications
Allergy
Pregnancy
Breast feeding
Liver and kidney disease:
Some antipruritic drugs may not
be safe for people with liver or
kidney disease, as they can cause
further damage to these organs.
Glaucoma

21. Role of Nurse
❖Nursesshouldassessthepatient'sskinconditionanditchingseverity
beforeadministeringanyantipruriticmedication.Theyshouldalso
reviewthepatient'smedicalhistory,includingallergiesandcurrent
medications.
❖Nursesshouldmonitorthepatient'sresponsetotheantipruritic
medication,includinganychangesinitchingseverityorskin
condition.

22. TOPICAL APPLICATIONS FOR SKIN MUCOUS
MEMBRANE
Demulcents
❑Theseareinertsubstancesthatsootheinflamed/denudedmucosa/skinby
preventingcontactwithsurroundings.
❑Highmolecularweight.
❑Thickviscoussolutioninwater.
❑Methylcellulose–Bulkpurgative,contactlenssolutionExamplesare
Glycerin–Gum/throatpaints.
Emollients
❑Oilysubstancesusedto:softenandsoothe/protecttheskinandusedas
vehicleforointment.
❑Formanocclusivefilm,preventingevaporation→restoreelasticityof
crackedanddryskin

23. AbsorbentsandProtectives
Finelypowdered,inertandinsolublesolidscapableofbindingnoxious
substancesandirritantstotheirsurfaceandprovidephysicalprotection.
Astringents
❖Drugswhichprecipitatesurfaceproteinofmucousmembraneand
abradeskinandprotecttheunderlyingsurface.
❖Itmakessurfacemechanicallystronger.