BNF for Children 2011-2012

592 13.10.4 Parasiticidal preparations BNFC 2011–201213 SkinScabiesPermethrin is used for the treatment of scabies (Sarcoptesscabiei); malathion can be used if permethrin isinappropriate.Benzyl benzoate is an irritant and should be avoided inchildren; it is less effective than malathion and permethrin.Ivermectin (available from ‘special-order’ manufacturersor specialist importing companies, see p. 809),is used in combination with topical drugs, for the treatmentof hyperkeratotic (crusted or ‘Norwegian’) scabiesthat does not respond to topical treatment alone.Application Although acaricides have traditionallybeen applied after a hot bath, this is not necessaryand there is even evidence that a hot bath may increaseabsorption into the blood, removing them from their siteof action on the skin.All members of the affected household should be treatedsimultaneously. Treatment should be applied to thewhole body including the scalp, neck, face, and ears.Particular attention should be paid to the webs of thefingers and toes and lotion brushed under the ends ofnails. Malathion and permethrin should be appliedtwice, one week apart. It is important to warn users toreapply treatment to the hands if they are washed.Children with hyperkeratotic scabies may require 2 or3 applications of acaricide on consecutive days toensure that enough penetrates the skin crusts to killall the mites.Itching The itch and eczema of scabies persists forsome weeks after the infestation has been eliminatedand treatment for pruritus and eczema (section 13.5.1)may be required. Application of crotamiton can be usedto control itching after treatment with more effectiveacaricides. A topical corticosteroid (section 13.4) mayhelp to reduce itch and inflammation after scabies hasbeen treated successfully; however, persistent symptomssuggest failure of scabies eradication. Oral administrationof a sedating antihistamine (section 3.4.1) atnight may also be useful.Head liceDimeticone is effective against head lice (Pediculushumanus capitis) and acts on the surface of the organism.Malathion, an organophosphorous insecticide, isan alternative but resistance has been reported. Benzylbenzoate is licensed for the treatment of head lice but itis not recommended for use in children.Head lice infestation (pediculosis) should be treatedusing lotion or liquid formulations only if live lice arepresent. Shampoos are diluted too much in use to beeffective. A contact time of 8–12 hours or overnighttreatment is recommended for lotions and liquids; a 2-hour treatment is not sufficient to kill eggs.In general, a course of treatment for head lice should be2 applications of a parasiticidal product 7 days apart tokill lice emerging from any eggs that survive the firstapplication. All affected individuals in a householdshould be treated at the same time.Wet combing methods Head lice can be mechanicallyremoved by combing wet hair meticulously with aplastic detection comb (probably for at least 30 minuteseach time) over the whole scalp at 4-day intervals for aminimum of 2 weeks and continued until no lice arefound on 3 consecutive sessions; hair conditioner orvegetable oil can be used to facilitate the process.Several devices for the removal of head lice, such ascombs and topical solutions, are available and some areprescribable on the NHS (consult Drug Tariff—seeAppliances and Reagents, p. 797 for links to onlineDrug Tariffs).Crab licePermethrin and malathion are used to eliminate crablice (Pthirus pubis); permethrin is not licensed for treatmentof crab lice in children under 18 years. An aqueouspreparation should be applied, allowed to dry naturallyand washed off after 12 hours; a second treatment isneeded after 7 days to kill lice emerging from survivingeggs. All surfaces of the body should be treated, includingthe scalp, neck, and face (paying particular attentionto the eyebrows and other facial hair). A differentinsecticide should be used if a course of treatment fails.Parasiticidal preparationsDimeticone coats head lice and interferes with waterbalance in lice by preventing excretion of water; it is lessactive against eggs and treatment should be repeatedafter 7 days.Malathion is recommended for scabies, head lice andcrab lice (see notes above). The risk of systemic effectsassociated with 1–2 applications of malathion is consideredto be very low; however, except in the treatmentof hyperkeratotic scabies (see notes above), applicationsof malathion liquid repeated at intervals of less than 1week or application for more than 3 consecutive weeksshould be avoided since the likelihood of eradication oflice is not increased.Permethrin is effective for scabies. It is active againsthead lice but the formulation and licensed methods ofapplication of the current products make them unsuitablefor the treatment of head lice. Permethrin is alsoeffective against crab lice but it is not licensed for thispurpose in children under 18 years.DIMETICONECautions avoid contact with eyesSide-effects skin irritationLicensed use not licensed for use in children under 6months except under medical supervisionIndication and doseHead liceRub into dry hair and scalp, allow to dry naturally,shampoo after 8 hours (or overnight); repeatapplication after 7 daysHedrin c (Thornton & Ross)Lotion, dimeticone 4%, net price 50 mL = £2.98, 120-mL spray pack = £7.13, 150 mL = £6.92Note Patients should be told to keep their hair away from fireand flames during treatment