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AEs,adverseevents;CrCl,creatinineclearance;CYP3A,cytochromeP-450enzyme3A;GI,gastrointestinal;LFT,liverfunctiontests;OTC,
overthecounter;QTc,correctedQT-interval;RX,prescription.
SystemicAllylamineAntifungals
Terbinafine(Lamisil)isasyntheticallylaminederivativethatinhibitssqualeneepoxidase,akeyenzyme
infungalbiosynthesis.Thiscausesadeficiencyofergosterol,causingfungalcelldeath.Itisusedinthe
treatmentofonychomycosisandcanbeusedinothertineainfections.
Dosage
Thedoseforonychomycosistreatmentis250mgbymouthdailyfor6weeksifonthefingernailand12
weeksifonthetoenail.Variouspulse-dosingregimensexistandmaybeusedtoimprovecomplianceand
reduce cost and risk for adverse events (AEs); although pulse-dosing may result in treatment failure.
Clearanceisreducedbyabout50%whencreatinineclearanceislessthan50mL/min.
AdverseEvents
AEsincludediarrhea, dyspepsia, rash,increase inliver enzymes,andheadache.Evaluationof alanine
aminotransferaseandaspartateaminotransferaselevelsisrecommendedbeforestartingtherapyandat6
to 8 weeks into therapy if it is long term because it can cause liver failure, although this is rare.
Terbinafinemaypermanentlyalterabilitytotasteandsmell.Therapyshouldbediscontinuedifthepatient
reports taste or smell disturbances. Depressionhas also been reported, and it is important to counsel
patientsonthisadverseeffectandtoreportitimmediately.
Interactions
Terbinafine may increase the serum concentration of clozapine, amitriptyline, and imipramine.
Terbinafinemaydecreasetheserumconcentrationoftamoxifenandtramadol.
SystemicAzoleAntifungals
Systemicazoles inhibit cytochrome P-450 (CYP) enzymesand fungal 14-alpha-demethylase, inhibiting
synthesis of ergosterol. Systemic therapy is required for tinea capitis and tinea unguium. Itraconazole
(Sporanox),asystemicazole,hasahighaffinityforkeratinandislipophilic,whichcauseshighlevelsto
accumulateinthehairandnail.Ithasalonghalf-life,sopulsedosing,inwhichperiodsofdrugtherapy
are alternated withperiods without therapy,is feasible. The capsule requires gastric acidity to aid in
absorptionandthereforeshouldbetakenwithfood.Itraconazolesuspensionshouldbetakenonanempty
stomachtoincreaseabsorption.Thesetwoformulationsarenotinterchangeable.
Dosage
The dose of itraconazole is 200 mg once daily for 12 weeks for toe onychomycosis. For fingernail
onychomycosis,thedoseis200mgtwicedailyfor1week,then3weeksoff,andrepeatdosingwith200
mgtwicedailyfor1week.Thispulseregimenmayalsobedonefortoeonychomycosis,buttherepeat
dosingisdonefortwomoretimesaftertheinitialweek.Itraconazoleisnotrecommendedforchildren,
andingestionoffoodincreasesabsorption.
Variousregimensoffluconazolehavebeenstudiedforthetreatmentoftineainfections.Onesuchis150
mg once weekly for 2 to 6 weeks for the treatment of tinea pedis. For tinea corporis or cruris, the
treatmentdurationisusually2to4weeks.Fluconazolehasnotbeenextensivelystudiedinpediatricsfor
thetreatmentoftineainfections.
Contraindications
AllsystemicazolescanprolongcorrectedQT-interval(QTc)interval.Cautionshouldbeusedwhenusing
otherdrugsthatcanalsoprolongQTcinterval,especiallydrugsthataremetabolizedbyCYP3A4,suchas
erythromycin and quinidine, as their use with azoles is contraindicated. Azole antifungals inhibit
CYP3A4. Systemic azole antifungals should be avoided in pregnancy. Itraconazole has many
contraindications.Itshouldnotbeusedforskininfectionsinpatientswithventriculardysfunctionsuchas
heartfailureandwomenwhoareplanningtobecomepregnant.
AdverseEvents
Adverse effects associated with systemic azole therapy include GI upset, rash, fatigue, hepatic
dysfunction,edema(withitraconazole),andhypokalemia.
Interactions
ConcomitantusewithQTc-prolongingdrugsshouldbeavoided.Itraconazolecapsulesshouldnotbetaken
withantacidsasitneedsanacidicenvironmentforabsorption.Itraconazoleshouldnotbeusedinpatients
takingticagrelor,rivaroxaban,ivabradine,ordofetilide.
SeleniumSulfide
Seleniumsulfidehasantifungalproperties.Itisappliedonceadaytotheaffectedskinfor10minutesand
thenrinsedoffdailyfor 1 week.Itshould be used withcautionininstancesofacuteinflammationor
exudation.Skinfolds andgenitaliaarecarefullyrinsed.Seleniumsulfidemustbekeptawayfromeyes.
Potentialadverseeffectsincludeirritationandhairloss.
Nystatin
Nystatin(Mycostatin)isa fungicidethatbindsto sterolsinthecellmembraneofthefungus,causinga
changeinthemembrane’spermeability.Thisallowsintracellularcomponentstoleak,therebycausingcell
death. Nystatincreamis preferred over ointment for treatment in intertriginousareas. Moist areas are
bettertreatedwithnystatinpowder.
SelectingtheMostAppropriateAgent
Topicalagentsworkwellformosttineasbutnotfortineacapitisandtineaunguium.Tobeeffective,all
therapymustbeadequateindoseandduration.Ifapetcarriesthefungus,thepetmustbetreated.
Whenselectinganoral agent totreat onychomycosis, considerationmustbe giventothe cost ofthe
agent,patientmotivationandcompliance,theageandhealthofthepatient,anddruginteractionsandside
effectprofileofthemedications.
First-LineTherapy:Tinea
Topicaltherapyisrecommendedforcasesoftineacorporis,pedis,cruris,ormanuumwhentheinfection
affectsalimitedarea. Thetopicalantifungalis applied3 cmbeyondthemarginofthelesion.Therapy
shouldcontinueforatleast2weeksandfor1weekafterthelesionclears.
Tineacapitiscanonlybecuredwithoral therapysincetopicaltherapiescannotadequatelypenetrate
the hair follicles. Therapy for tinea capitis caused by Microsporum is microsize griseofulvin
administeredwithmilkorfoodtopromoteabsorption.Treatmentisfor6weeks.Theadultdoseis500
mgdaily,andthepediatricdoseis10mg/kg/d.ForinfectionscausedbyT.tonsurans,terbinafine250mg
orallydailyshouldbeusedfor4weeksinchildrenatleast4yearsofageandgreaterthan35kg.Children
whoweighlessthan25kgaredosedwith125mgandthosewhoweighbetween25and35kgaredosed
with187.5mgdaily.Childrenmayattendschoolduringtherapy.
First-linetherapyfortineaunguiumconsistsofsystemicterbinafinebasedonaCochranereviewthat
showed that both terbinafine and azole antifungals are better than placebo at achieving clinical and
mycologicalcure,butterbinafineisprobablybetterthanazoleantifungalsatachievingclinicalcurerates
withnosignificantdifferenceinAErates(Kreijkamp-Kaspersetal.,2017).Dosingforadultsis250mg
orallydailyforatleast6weeksforfingernailsand12weeksfortoenails.Treatmentsuccessratesvary
between51%and71%.Useofterbinafinemaybelimitedduetoitsadverseeffectprofile,especiallyin
older adults,whomaybemorevulnerabletoitseffects.Topicalpreparationsarenoteffectivebecause
theypenetratethenailspoorly.
Second-LineTherapy:Tinea
Topicaltherapiesareoftensuccessfulfortineacorporis,pedis,cruris,andmanuum,althoughsecond-line
therapyis needediftheinfectionfailstorespondtotopicaltherapyorifthereisextensiveandchronic
disease.Second-linetherapyconsistsofterbinafine250mgorallydailyfor1to3weeksoritraconazole
100to200mgorallydailyfor1to4weeks.
Second-line therapy for tinea capitis involves using an alternate antifungal such as itraconazole,
terbinafine,fluconazole,orgriseofulvin.
Second-linetherapyfortineaunguiumincludessystemicazoleantifungalsandtopical nail solutions.
Itraconazoleis givenbypulse dosing,200 mgtwicedailywithafullmealfor7 consecutivedaysper
month.Treatmentforfingernailslasts2monthsandfortoenails3months.Alsoeffectivefortoenails is
200mgitraconazoleperdayfor12weeks.Pulsedosinghaslessimpactontheliverandismorepopular
than continuous dosing due to fewer side effects, easier patient compliance, and decreased cost.
Fluconazolecanbegivenatadoseof150to300mgonceweeklyfor12to24weeksforfingernailsand
24to52weeksfortoenails.Whensystemictherapywithterbinafineandazolesiscontraindicated,topical
nail treatments can be used. Available agents are efinaconazole (Jublia) 10% solution, tavaborole
(Kerydin) 5% solution, and ciclopirox (Ciclodan) 8% solution. Therapy lasts for 48 weeks, although
mycologicandclinicalcureratesarelow.Itisimportanttokeepinmindthatthesetopicalnailsolutions
canbe expensive butmaybe the only optionfor those who cannot or are unable to tolerate systemic
therapy.Inclinicalpractice,patientsareseldomplacedonsystemictherapyduetorisksassociatedwith
theiruse.
First-LineTherapy:TineaVersicolor
Seleniumsulfide 2.5% solution is applied onceadayfor 7 days.Pyrithionezinc(Head & Shoulders
shampoo) may also be used. An antifungal topical agent can also be used, such as terbinafine,
ketoconazole,orsulconazolenitratecreamstwicedailyfor2weeks.
Lesionsmayreappearbecausetheinfectionisaresultofmicroorganismsthatnormallyinhabittheskin,
sotwicemonthlyapplicationofseleniumsulfideissuggestedasprophylaxisfor6monthsfollowinginitial
treatment.
Second-LineTherapy:TineaVersicolor
Forresistantorwidespreadtineaversicolor,systemictherapywithitraconazole200mgorallyfor5days
orfluconazole300mgorallyonceweeklyfor2weeksmaybeprescribed.Ifinfectionreoccursinwarm
weather,itisappropriatetorepeatthepreviouslyeffectiveregimen.
First-LineTherapy:Candidiasis
For cutaneouscandidiasis, topical treatment withnystatin, clotrimazole, ketoconazole, oxiconazole, or
econazoleshouldbeappliedtwicedailyuntilinfectionclears.Fordiaperdermatitiscausedbycandida,
nystatinointmentorcreamcanbeappliedtwotofourtimesdaily.
Second-LineTherapy:Candidiasis
Forfailuretorespondtotreatment,onceweeklyoralfluconazole150mgfor4weeksmaybeprescribed
toadultsforintertrigo.
MonitoringPatientResponse
Whenpatientsuseterbinafine,fluconazole,oritraconazole,liverfunctiontestsshouldbemonitoredat6
to 8 weeks. Follow-up evaluations need to monitor both the effectiveness of the therapy and labs to
evaluateliver,kidney,andhematopoieticfunction.Iftestsdiscloseelevatedliverfunctionorifthereisan
acutechangeinrenalfunction,drugtherapyshouldbediscontinued.Foritraconazole,patientsshouldbe
monitoredforsignsandsymptomsofheartfailure.
For cutaneous candidiasis, response to therapy should be evaluated in 2 weeks. Human
immunodeficiencyvirusinfectionanddiabetesmellitusshouldberuledoutinpatientswhohaverecurring
problemswithcandidiasis.
PatientEducation
Animportantroleofthepractitioneristeachingthepatientabouthygieneandwaystoavoidtransferring
fungalinfectiontoothers.Patientsshouldbeinstructedtocompletethefullcourseoftreatmentandnotto
stoptreatmentwhensymptomssubside.Parentsandothercaregiversalsoneedtoknowthatchildrencan
attendschoolwhilebeingtreated.
It is important to inform patients with tinea versicolor that it may take several months for the
discoloration to disappear. Prophylactic application of selenium sulfide shampoo twice a month can
preventrecurrence.
ComplementaryandAlternativeMedicine
Tea tree oil has natural antifungal compounds that help kill the fungi that cause fungal infections,
particularlyininterdigitaltineapedis(Satchelletal.,2002).Dataonthisaresparse,andthisshouldonly
beusedifpatientsareresistanttorecommendedtherapy.
VIRALSKININFECTIONS
Introduction
Virusesproducingskinlesionsmaybecategorizedintothreegroups: herpesviruses,papillomaviruses,
andpoxviruses.Viruses’geneticmaterialcanbemadeofribonucleicacid(RNA)ordeoxyribonucleic
acid(DNA).Herpesviruses,papillomaviruses,andpoxvirusesareallDNAviruses.
Viruses are obligate smallparasites thatconsist of a nucleic acid core surrounded byone or more
proteins.Ahostcellisrequiredforviralreplication.Severalmechanismsexistforviralreplication,and
differentDNA virusesreplicatebytheir ownspecificmechanism.Poxvirusesreplicateentirelyinthe
cytoplasm.Herpesvirusesandpapillomavirusesreplicateinthenucleusofthehostcell.Poxvirusesare
notdiscussedinthischapter,sincetheyareveryrare.Anexampleofapoxvirusissmallpox,whichhas
beeneradicatedfromtheworldbywidespreaduseofthesmallpoxvaccine.
Causes
HerpesVirusInfections
Nine typesofherpes viruses are associated withhumanillness: herpes simplexvirustype1 (HSV-1),
herpessimplexvirustype2(HSV-2),varicella-zostervirus(VZV),Epstein-Barrvirus,cytomegalovirus,
humanherpesvirustype6(HHV-6)typesAandB,andKaposisarcoma-associatedherpesvirus
(HHV-8).
HSV-1infectionusuallyinvolvestheface,mostlymouthandeyes,andskinabovethewaist.Itismost
oftenthecauseofcoldsores,orherpessimplexlabialis,andherpeticwhitlow,aninfectiousblisteronthe
digits.Whitlowinfection commonly isthecause of HSV-1spread tothedigitsfromthumb-sucking in
children or to health care professionals who acquire HSV-1 infection while working without gloves.
HSV-2ismostcommonlyassociatedwiththegenitaliaandtheskinbelowthewaist,althoughHSV-1can
also infectthoseareas.Alife-threateningneonatalinfectionis associatedwithHSV-2inababywhose
motherisinfectedwiththevirus;theinfectionistypicallytransmittedduringvaginalbirth.
Herpeszoster(shingles)andvaricella (chickenpox)aretheresultofVZV reactivationandinfection,
respectively.Theincidenceofherpeszosterincreaseswithageandismostcommoninolderadultsand
immunocompromised individuals. Varicella infection occurs mostly in children, although with
vaccination,activeinfectionisuncommon.Riskfactorsforherpeszosterincludeagemorethan50years,
female gender, white race, immunodeficiency, solid organ transplant, and hematologic malignancy.
Infectious mononucleosis is a result ofEpstein-Barr virus infection.HHV-6is associatedwith a mild
childhoodillnesscalledroseola.HHV-8isassociatedwithKaposisarcoma,especiallyinpatientswith
HIVinfection.HSV-1andVZVarediscussedinthischapter;HSV-2isdiscussedinChapter35.
Warts(Verrucae)
Verrucae,or warts,arecaused bythehumanpapillomavirus (HPV).Therearemorethan100typesof
HPV.Theyaretransferredbyskin-to-skincontact.Thecommonvirusescanbeclassifiedasthosecausing
anogenitalinfections andnon-anogenital infections. Anogenitalinfectionsare discussed in Chapter 35.
Non-anogenitalHPVinfectionstypicallypresentaswarts.Theyareverycommon,especiallyinchildren.
At some timeintheir life,approximately20%of school-agechildrenhave oneormorewarts, which
usuallyregressspontaneously(Becker&Childress(2018)).
Itisthoughtthatmicrotraumasontheskinprovide anentrywayforthevirus.Thevirusthencauses
keratinocyte proliferation, whichresults intheformation ofa wart onthe surfaceof the epidermis. In
immunocompromised individuals, thisis abenigninfectionandis self-limiting.HPVis transmittedby
directcontactwithanobjectorsomeonesheddingthevirus.
FactorsthatpredisposeindividualstoHPVincludethefollowing:
•Immunosuppression
•Walkingbarefoot
•Useofcommunalshowers
•Handlingrawmeat,fish,orotheranimalmatter
Pathophysiology
HerpesVirusInfections
Herpesvirusesreplicatetheirownpolymerasealongwithseveraloftheirownenzymes.HSV-1andVZV
arehighlycontagious,especiallywhenlesionsareinthevesicularphase.Thevirusisspreadbydirect
contactwithwetvesicles on skinor mucousmembranes.The individual isnolonger contagiousonce
lesionshavecrustedover.
After primary infection with HSV-1 or varicella, most often in childhood, the virus retreats to the
ganglia, where it remains latent until it is reactivated. The virus can be latent for years. For HSV-1,
triggers such as stress, extremes in temperature, sun exposure, and weakened immune system can
reactivatethelatentinfection.Forherpeszoster,thevirustypicallystaysdormantformanyyearsandis
reactivatedwithnoapparentdirectcause.Eitheractiveinfectionwithvaricellaorimmunizationwiththe
varicella vaccineas achildcauseslatentdisease,althoughthosewhoare vaccinatedare lesslikelyto
haveactivationofherpeszoster.Becauseoftheseviruses’abilitytostaydormantintheganglia,theyare
never fullyeradicated.RecurrentinfectioniscommonforHSV-1, andalthoughrecurrentinfectionwith
herpes zoster is possible, it is not commonin immunocompetent individuals. Additionally, due to the
locationofthelatentvirus,reactivationcancauseneuropathic pain,a commoncomplicationinherpes
zoster.InHSV-1,atinglyandburningsensationcanbefeltatthesiteofinfection.
Warts(Verrucae)
HPVproteinscontributetotheinitiationofDNAreplication.Thevirusentersthroughskinabrasionsand
infectsthecellsofthebasallayersoftheskin.Viralreplicationisslow,withanincubationperiodof4to
6 months. Once viral replication in the basal layers of the skin produces enough keratin, a wart is
producedonthesuperficiallayeroftheskin.
DiagnosticCriteria
HerpesVirusInfections
InfectionwithHSV-1causesvesiculareruptionsthatarepainfulandoftenrecurrent.Prodromalsymptoms
can occur with recurrent infections and include burning, tingling, or itching. Within hours, the lesion
presentsasasinglevesicleorgroupofvesiclesthatoverlieanerythematousbase.Theybecomepustules
andbecome crusted or erode. Lesions commonly recur at theprimary site innervated by the ganglion
inhabitedbythevirus.Thediagnosisistypicallymadefromclinicalpresentationandhistory.Objective
toolssuchasviralculture,serology,directfluorescentantibodytesting,polymerasechainreaction(PCR),
andTzancktestcanbeusedtoconfirmdiagnosis. Thesensitivityofviral culturedecreases withmore
timelapsedfromthefirstappearanceofsymptoms,anditisbesttocollectthespecimenwithin24to28
hours. Viral cultures can take up to 7 days to yield a positive result. Serology is not recommended
because ofits poorspecificityfor active disease since it cannotdifferentiate new fromold infection.
Serology,however,canbeusedfordetectingHSV-1exposure.Directfluorescentantibodytestinghaslow
sensitivity. PCRis the mostsensitive and specific testfor detectingHSV-1 andyields results quickly
(Milleretal.,2018).Itisrecommendedtoswabandtestun-crustedlesionstogetanaccurateresult.The
TzancktestcannotdifferentiatebetweenHSV-1andHSV-2andrequiresskilledpersonneltocollectand
examinethespecimenundermicroscope(Usatine&Tinitigan,2010).Itisnotrecommendedduetolow
sensitivity.
Thetwodifferentdiseasescausedbyvaricella(chickenpoxandshingles)havesimilarsymptoms.After
anincubationperiodof10to20days,chickenpox(primaryvaricella)manifestswithfeverandmalaise
followedbytheoutbreakofitchy,vesicularlesionsonanerythematousbase.Theoutbreakusuallybegins
onthetrunkandprogressestotheextremitiesandface.Primaryvaricellaoccursmostofteninchildren.
Adults infected with primary varicella tend to have more systemic effects, especially if they are
immunocompromised.
Areactivationofvaricellainthedorsalrootganglionisreferredtoasherpeszoster,orshingles.The
infectioncharacteristicallybeginswithneuralgiaintheaffecteddermatome,followedbyanoutbreakof
groupedvesiclesonanerythematousbase,clusteredinaunilateralpatternofthedermatome.Intwothirds
ofinfections,thelesionsareonthetrunk.Additionalsymptomsincludefever,myalgia, andincreasing
localizedpain.ThemostcommonpresentationofherpesvirusinfectioninolderadultsisVZVintheform
ofherpeszoster.Asignificantcomplicationofherpeszosterispostherpeticneuralgia,whichisdefinedas
paininthedermatomesitethatlastslongerthan6weeksafterresolutionoftheinfection.
VZVcanbediagnosedobjectivelysimilarlytoHSV-1.ThemostsensitiveandspecificmethodisPCR.
Thetestis quickandhasbecomea standardapproachto testing.Serology,directfluorescentantibody
testing,andculturearelesssensitivethanPCRandnotcommonlyperformedifPCRisavailable.
Warts(Verrucae)
Wartsarepapillomatous,corrugated,hyperkeratotic growthsfoundonlyontheepidermis,especiallyin
areassubjectedtorepeatedtrauma.Theycanbesolitary,multiple,orclustered.Wartsarenamedbased
ontheirclinicalappearanceorlocation.Diagnosisismadebasedonclinical appearance.Labtestsare
rarelyneededtomakeadiagnosis.
Plantarwarts(verrucaplantaris)commonlyoccurontheheels,toes,solesofthefeet,andthepalmsof
thehands.Verrucavulgaris,commonwarts,presentsonthehands,fingers, knees,elbows,or toesor at
sites of trauma. They are flesh-colored-to-brown, hyperkeratotic papules and have an asymmetric
distribution.Flatwarts(verrucaplana)are locatedontheface,neck,andchestorflexorregionsofthe
forearmsandlegs.Theyareflatandwelldefinedandmaybefleshcoloredordarkerbrown.Flatwarts
canbespreadbyshavingandarefoundinthebeardareainmenandonthelegsinwomen.Filiformwarts
(verrucafiliformis)arefoundprimarilyonthefaceandneckandpresentastan,finger-likeprojections.
InitiatingDrugTherapy
Herpes labialis is usually self-limiting, lasting approximately 7 to 10 days without scarring. Initial
infection is usually the most severe, and recurrent infections are milder and shorter in duration. It
typicallydoesnotrequiretreatment,althoughitcanbebothersomeandvisuallyunappealing,encouraging
the affected individual to seek treatment. Topical antivirals can be used, although they are marginally
efficacious.Systemictherapywithoralantiviralsmayshortenthedurationofpainandinfection.
ForprimaryVZVinfectionsthatmanifestaschickenpox,systemictherapyisusedonlyinspecialcases,
andisnotrecommendedforuncomplicateddiseasethatisself-limiting.Iftreatmentisinitiated,itshould
beinitiatedwithin24hoursfromthefirstvaricellarashfortreatmenttobeeffective.ForVZVinfections
thatmanifestasherpeszoster,antiviralagentsmayhelprelievesymptoms.Patientsshouldbetreatedif
therashhasbeenpresentforfewerthan72hoursorifnewlesionsarestilldeveloping.Iftherapystarts
within72hoursoftheappearanceofthelesion,systemictherapydecreasesthedurationoftherashand
theacutepainassociatedwithherpeszoster.Inaddition,anypatientwhoisimmunocompromisedshould
be considered for treatment with IV antivirals and inpatient observation. Antiviral agents used are
acyclovir,famciclovir,andvalacyclovir.Allantiviralagentshavebeenshowntoshortenthedurationof
herpeszosterinfectionandtheseverityofacutepain,butnonepreventpostherpeticneuralgia.
The natural historyof cutaneousHPVinfectionis spontaneous resolutionin monthsor a few years.
Therapyisnotneededunlessthepatientreportspainorrequestsremovalforcosmeticpurposes.Wartson
the face need to be removed by a dermatologist, usually with liquid nitrogen cryotherapy. Topical
treatmentwithsalicylicacid(DuoFilm)isusuallythestartingpointforallotherwarts.Itiseasiertotreat
smallverrucaeratherthanwaitinguntiltheyarelarge.
GoalsofDrugTherapy
Inherpesvirusinfections,thegoaloftherapyistoreducethedurationofsymptoms,suppresspain,and
stopviralshedding.Itisimportanttoknowthatherpesinfectionsarenevercuredsincethevirusretreats
intothegangliaandmaybereactivated.
Thegoaloftherapyforwartsiseradicationofthelesionsafelyandeffectivelywhilealsokeepingin
mindthecostoftherapy.ThereisnowaytoactuallykillHPV.
TopicalAntiviralAgents
Acyclovir5% (Zovirax)andpenciclovir(Denavir) areavailable totreatherpes labialis.Theseagents
workbyinhibitingviralDNAsynthesis(Table13.7).Theymaydecreasetimetoheal,althoughclinical
significanceismarginal(Spruanceetal.,1997;Worrall,2009).Patientsshouldapplytopicalacyclovir
fivetimesdailyfor4days.Penciclovirisappliedevery2hoursduringwakinghoursfor4days.Adverse
effectsincludemildskinirritationandpruritus.
TABLE13.7
OverviewofAntiviralAgentsforHerpesVirusInfections
*Dosinginchartisfortheimmunocompetentpatient.Refertotextfordosingintheimmunocompromisedpatient.
CNS,centralnervoussystem;HSV,herpessimplexvirus;LFT,liverfunctiontest;OTC,overthecounter;VZV,varicella-zostervirus.
Docosanolcream(Abreva)isasaturatedaliphaticalcoholwithantiviralpropertiesmarketedforthe
treatment of cold sores, although its clinical significance in reducing healing time and duration of
symptomsisminimal(Usatine&Tinitigen,2010).Itisavailableoverthecounter.Itisessentialtoinform
patientstheyshouldapplytopicaltreatmentswithagloveoranapplicatorsothattheydonotinfectother
areasofthebodywiththevirus.
SystemicAntiviralAgents
Systemic antivirals used for herpes virus include acyclovir (Zovirax), famciclovir (Famvir), and
valacyclovir (Valtrex). Famciclovir and valacyclovir have higher oral bioavailability than acyclovir.
Systemicantiviralsarehighlyeffectiveagainstherpesvirus.Ingeneral,antiviraltherapyisrecommended
foradolescents,adults,andhigh-riskpatientsbutnotusuallyforhealthychildrenyoungerthanage12(see
Table13.7).
Contraindications
Cautionshouldbeusedinpatientswithrenaldiseasebecauseantiviralsareexcretedrenally.Creatinine
clearanceshouldbecalculatedandusedtorenallyadjustantiviraltherapy.
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