Pyrethrins with Piperonyl Butoxide (Monograph)

Brand names: A200, Licide, Pronto, RID
Drug class: Scabicides and Pediculicides
ATC class: P03BA
VA class: AP300
CAS number: 8003-34-7

Introduction

Pediculicide; fixed-combination preparation containing pyrethrins (a pediculicide) and piperonyl butoxide (has little or no insecticidal activity but potentiates that of pyrethrins).^a

Uses for Pyrethrins with Piperonyl Butoxide

Pediculosis

Topical treatment of pediculosis capitis (head lice infestation).^{103 104 107 112 117 120 121 122 123}

An alternative rather than a preferred treatment for pediculosis capitis.^{107 108} Permethrin 1% generally considered the treatment of choice, and malathion 0.5% is recommended when permethrin resistance is suspected.^{103 107 108 113 114 116 117 125}

Base selection of a pediculicide on efficacy (including both pediculicidal and ovicidal activity), safety, cost, availability, ease of application, age of patient, presence of other scalp infections, patient preference, severity of the infestation, potential for transmission, number of recurrences, and the pattern of resistance in the geographic region.¹¹³

Topical treatment of pediculosis pubis (pubic lice infestation).^{101 104 112 115 120 121 122 123} Considered a pediculicide of choice by CDC and others for treatment of pediculosis pubis, including in HIV-infected patients.^{101 104 112 115}

Topical treatment of pediculosis corporis (body lice infestation).^{103 120 121 122 123 124 125} In some cases, body louse infestations may be treated by improved hygiene and by decontaminating clothes and bedding by washing at temperatures that kill lice.^{103 125} If the infestation is severe, a pediculicide should also be used (e.g., topical permethrin, topical pyrethrins with piperonyl butoxide, topical malathion, oral ivermectin).^{124 125}

One of several options recommended for treatment of pediculosis corporis in the adjunctive treatment of epidemic (louse-borne) typhus.¹⁰³ The causative agent of epidemic typhus (Rickettsia prowazekii) is transmitted person-to-person by Pediculus humanus corporis and thorough delousing (especially among exposed contacts of individuals with typhus) is recommended in epidemic situations.¹⁰³

Scabies

Not effective for treatment of scabies (mite infestation).^a

Pyrethrins with Piperonyl Butoxide Dosage and Administration

General

Measures to Avoid Reinfestation and Transmission

• To avoid reinfestation or transmission of pediculosis or scabies, most experts recommend that clothing and bed linen that may have been contaminated by the infested individual during the 2 days prior to treatment should be decontaminated (machine-washed in hot water and dried in a hot dryer, dry-cleaned, or treated with an appropriate pesticide) or removed from body contact for ≥72 hours.^{103 104 106 113}

• Although it may not be necessary, items that cannot be laundered or dry-cleaned should be removed from contact and sealed in a plastic bag for 10–14 days.^{103 106 116}

• Combs and brushes used by the infected patient may be disinfected by soaking in hot water (temperature >54°C) for 5–10 minutes;^{103 106} alternatively, they can be soaked in alcohol or a pediculicide for 1 hour.^{106 112}

• Furniture and floors of rooms inhabited by patients infested with lice should be thoroughly vacuumed.^{103 106 116} Fumigation of living areas is not necessary and is not recommended.^{103 106 114 116}

• In the treatment of pediculosis capitis (head lice infestation), a fine-toothed comb often is recommended to remove any remaining nits (eggs) or nit shells.^{103 106 112 113 116 117 118} Some experts do not consider nit removal necessary since only live lice can be transmitted, but recommend it for aesthetic reasons and to decrease diagnostic confusion and unnecessary retreatment.^{103 116 117 118} Others strongly recommend removal of nits (especially those within 1 cm of the scalp) since no pediculicide is 100% ovicidal and potentially viable nits may remain on the hair after pediculicide treatment.^{103 116 117 118} Although many schools will not allow children with nits to attend, AAP and other experts consider these no-nit policies excessive.^{103 114 116}

Administration

Topical Administration

Apply topically, usually as a shampoo containing 0.33% pyrethrins and 4% piperonyl butoxide.^{120 121 122 123}

For external use only.^{120 121 122 123} Do not administer orally and do not apply to mucous membranes (e.g., inside the nose, mouth, or vagina).^{120 121 122 123}

Do not apply to eyebrows or eyelashes and avoid contact with eyes.^{120 121 122 123} Eyes should be closed tightly and covered with a soft towel or washcloth while the shampoo is applied to scalp hair or washed off.^{120 121 122 123}

Shake containers of pyrethrins with piperonyl butoxide before using.^{120 123}

Dosage

Pediatric Patients

Pediculosis

Pediculosis Capitis (Head Lice Infestation) or Pediculosis Corporis (Body Lice Infestation)

Topical

Apply to dry scalp hair or other affected areas in an amount sufficient to thoroughly wet the area.^{120 121 122 123} If treating head lice, first apply behind ears and to back of neck.^{120 121} After 10 minutes, add warm water to form a good lather, wash, and thoroughly rinse with water until all lather is gone.^{120 121 122 123} Dry the hair with a clean towel and comb with a fine tooth comb to remove any remaining nits.^{120 121 122 123}

One treatment may be successful, but treatment should be repeated after 7–10 days to kill any newly hatched lice.^{103 107 113 116 117 121 122 123} Do no use more than twice in 24 hours.¹²³

Adults

Pediculosis

Pediculosis Capitis (Head Lice Infestation) or Pediculosis Corporis (Body Lice Infestation)

Topical

Apply to dry scalp hair or other affected areas in an amount sufficient to thoroughly wet the area.^{120 121 122 123} If treating head lice, first apply behind ears and to back of neck.^{120 121} After 10 minutes, add warm water to form a good lather, wash, and thoroughly rinse with water until all lather is gone.^{120 121 122 123} Dry the hair with a clean towel and comb with a fine tooth comb to remove any remaining nits.^{120 121 122 123}

One treatment may be successful, but treatment should be repeated after 7–10 days to kill any newly hatched lice.^{103 107 113 116 117 121 122 123} Do not use more than twice in 24 hours.¹²³

Pediculosis Pubis (Pubic Lice Infestation)

Topical

Apply to the pubic area.¹⁰⁴ After 10 minutes, rinse off with water.¹⁰⁴

CDC recommends reevaluating the patient 1 week after treatment if symptoms persist;¹⁰⁴ retreatment may be necessary if lice or eggs are found.¹⁰⁴ Some clinicians recommend routine retreatment 7–10 days after initial treatment.¹⁰³ If retreatment is necessary, CDC recommends use of an alternative regimen.¹⁰⁴

Cautions for Pyrethrins with Piperonyl Butoxide

Contraindications

• Known hypersensitivity or intolerance to any ingredient in the formulation.

Warnings/Precautions

Sensitivity Reactions

Asthmatic Episodes

May cause breathing difficulty or an asthmatic episode in susceptible individuals.^{120 121 122}

Use with caution in individuals allergic to ragweed.^{120 121 122 123}

Discontinue use and contact a clinician if breathing difficulties occur.^{120 121}

Contact Dermatitis

Pyrethrins may be contact allergens; sensitization characterized by dermatitis may be due to impurities from the pyrethrum flowers.^a

Commercially available preparations of pyrethrins are refined, and only mild skin sensitization has been reported.^a

General Precautions

Administration Precautions

Avoid contact with the eyes since ocular irritation may occur.^{120 121 122 123} Do not use for treatment of pediculosis of the eyebrows or eyelashes.^{120 121 122 123}

If accidental contact with the eyes occurs, the affected eye(s) should be flushed thoroughly with water.^{120 121 122 123} If eye irritation occurs, discontinue use and contact a clinician.^{120 121 122}

Avoid contact with mucous membranes (e.g., inside the nose, mouth, or vagina) since irritation may occur.^{120 121 122 123}

Dermatologic Reactions

Local irritation or erythema may occur.^{120 121 a}

If skin irritation or infection occurs, discontinue use and contact a clinician.^{120 121 122 123}

Do not use on acutely inflamed skin or raw, weeping surfaces.^a

Specific Populations

Pregnancy

CDC considers pyrethrins with piperonyl butoxide a pediculicide of choice when treatment is considered necessary in a pregnant woman.¹⁰⁴

Pregnant women should consult a clinician before self-medicating with pyrethrins with piperonyl butoxide ^{120 121 122}

Lactation

Not known whether distributed into milk. CDC considers pyrethrins with piperonyl butoxide a pediculicide of choice when treatment is considered necessary in a lactating woman.¹⁰⁴

Lactating women should consult a clinician before self-medicating with pyrethrins with piperonyl butoxide.^{120 121 122}

Pediatric Use

Should not be used in children <2 years of age unless directed by a clinician.^{120 121}

Keep out of reach of children.^{120 121 122}

Common Adverse Effects

Local irritation (erythema, pruritus, urticaria, edema, eczema).^{120 121 a 123}

Pyrethrins with Piperonyl Butoxide Pharmacokinetics

Absorption

Bioavailability

Pyrethrins is absorbed through intact skin when applied topically.^a Piperonyl butoxide is poorly absorbed through intact skin when applied topically.^a

Distribution

Extent

Information regarding systemic distribution of pyrethrins and piperonyl butoxide following topical application not available.^a

Elimination

Elimination Route

Information regarding elimination of pyrethrins and piperonyl butoxide following topical application not available.^a

Stability

Storage

Topical

Shampoo

Well-closed containers at <40°C, preferably between 15–30°C.^a

Actions and Spectrum

• Pyrethrins (also known as pyrethrum extract) contains the purified derivatives of pyrethrum flowers (Chrysanthemum cinerariaefolium) and is a complex of substances that includes the alcohols and esters of pyrethrolone and cinerolone, the alcohol of chrysanthemic acid, and the ester of pyrethric acid.^a Piperonyl butoxide is a synthetic piperic acid derivative.^a

• Following absorption through the chitinous exoskeleton of arthropods, pyrethrins stimulates the nervous system and blocks nerve impulse transmissions, resulting in paralysis and death.^a

• Piperonyl butoxide has little or no insecticidal activity, but potentiates that of pyrethrins by inhibiting the hydrolytic enzymes responsible for metabolism of pyrethrins in arthropods.^a

• Pyrethrins is active against Pediculus humanus var. capitis (head louse), P. humanus var. corporis (body louse), and Phthirus pubis (pubic or crab louse), and may have some activity against their nits (eggs).^a Pyrethrins also is toxic to houseflies, fleas, chiggers, and mosquitoes.^a

• Therapeutic failure and resistance to pyrethrins has been reported in P. humanus.^{107 116} The prevalence of resistance in the US is unclear.^{103 116}

• Treatment failures do not necessarily mean resistance is present since failures can also be related to misdiagnosis, noncompliance with the treatment regimen, and reinfestation.^{108 116}

Advice to Patients

• Importance of using only as directed.^{120 121 122 123}

• Advise patients regarding personal protective measures to avoid reinfestation or transmission of lice.^{103 104 106 113}

• Importance of not using on eyebrows or eyelashes and avoiding contact with the eyes since ocular irritation may occur.^{120 121 122 123} If accidental contact with the eyes occurs, the affected eye(s) should be flushed thoroughly with water.^{120 121 122 123}

• Importance of avoiding contact with mucous membranes (e.g., inside the nose, mouth, vagina).^{120 121 122 123}

• Advise patients to discontinue treatment and consult their clinician if skin or scalp irritation or infection is present or develops, if eyebrows or eyelashes are infested with lice, or if eye irritation occurs.^{120 121 122 123}

• Advise patients using pyrethrins with piperonyl butoxide that breathing problems or asthmatic episodes may occur in susceptible individuals.^{120 121} If breathing difficulties occur, discontinue treatment and consult a clinician.^{120 121}

• Importance of immediately consulting clinician and/or poison control center if pyrethrins with piperonyl butoxide is accidentally ingested.^{120 121}

• Importance of informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs.^{120 121 122}

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.^{120 121 122}

• Importance of informing patients of other important precautionary information.^{120 121 122} (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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