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Drug Update: Generalized Pruritus.

Pruritus is a symptom, not a disease. Treating the underlying condition is the cornerstone of therapy, but severe itching can be so tormenting that the symptom must be dealt with as the cause is sought.

Common causes include dry skin or scabies; less common triggers are drug reactions, allergic reactions, contact dermatitis, lichen planus, folliculitis, mycosis fungoides, or dermatitis herpetiformis. When no skin-associated cause exists, severe itching can also result from certain systemic diseases, including uremia, obstructive biliary disease, hematologic and myeloproliferative disorders, endocrine disorders, neurologic disorders, psychiatric disorders, polycythemia vera, and iron deficiency anemia.

Topical therapy is the first option to try. It not only provides some relief but can also fulfill a patient's often overwhelming desire to try to do something. Drug labeling cautions against using mid- to high-potency topical corticosteroids on large areas of skin or under occlusion because of potential systemic effects, but many dermatologists consider these only theoretical concerns.

Certain treatments, not listed in the chart, are excellent for the small number of patients whose pruritus has a specific etiology For example, cholestyramine and naltrexone are used when patients have pruritus secondary to liver failure. Naltrexone and erythropoietin are treatment options for patients whose pruritus is secondary to renal disease.

For patients with chronic pruritus, some experts prefer to use phototherapy in place of drug therapy because they consider it safer and more effective. Other physicians recommend long-term therapy with an antihistamine.

No dose adjustments for the listed drugs are required for elderly patients or for women who are breast-feeding. Hydroxyzine is contraindicated during early pregnancy; no dose adjustments are needed during pregnancy for the other listed drugs.
DRUG             DOSAGE          COST
TOPICAL DRUGS
hydrocortisone   3 times a day,  $4.72 (30 g,
                 as needed       1% cream) [*]
triamcinolone    3 times a day   $4.09 (15 g,
acetonide (0.1%)                 0.1% cream) [*]
pramoxine        2-3 times a day $4.15 (15 mL) [*]
hydrochloride
 (Prax)
doxepin          5 times a day   $23.57 (30 g) [*]
hydrochloride
 (Zonalon)
capsaicin        5 times a day   $7.98 (30 g) [*]
 (Zostrix)
INJECTABLE DRUGS
triamcinolone    3 mg/mL,        $8.95 (5 mL) [*]
acetonide        injected into
 (Tac-3)         pruritic lesion
prednisolone     300 mg/day IM   $4.98 [**]
acetate
ORAL DRUGS
hydroxyzine      25-50 mg once   $0.14 (50 mg) [**]
hydrochloride    daily to start
diphenhydramine  25-50 mg once   $0.14 (50 mg) [**]
hydrochloride    daily to start
doxepin          10-50 mg once   $0.19 (25 mg) [**]
hydrochloride    daily; increase
                 dose if needed
loratadine       10 mg once      $2.19 [**]
 (Claritin)      daily
prednisone       60 mg/day or    $0.14 (20 mg) [**]
                 less orally
amitriptyline    75 mg/day in    $0.42 [**]
hydrochloride    divided doses
DRUG             COMMENT [+]
TOPICAL DRUGS
hydrocortisone   Topical drugs are first-line treatment,
                 and topical steroids top the list. Safe
                 and inexpensive; practical for localized
                 pruritus. Do not use for dry skin;
                 instead, discourage frequent bathing and
                 prescribe emollients such as petroleum
                 jelly or vegetable shortening. Available
                 as cream, lotion, or ointment, in either
                 1% or 2.5% formulations.
triamcinolone    Midpotency steroid. For localized
acetonide (0.1%) pruritus, occlusive dressing increases
                 absorption and blocks itch-scratch cycle.
                 Can be used mixed with a soothing emollient
                 with menthol and phenol such as Sarna
                 lotion. Available as ointment or cream.
pramoxine        By itself, a second-line topical agent;
hydrochloride    especially useful for genital pruritus.
 (Prax)          Nonsensitizing. Can be combined with a mild
                 topical steroid. OTC formulation; 1% lotion.
doxepin          Expensive, sedating; practical only for
hydrochloride    localized disease. Potentiated by mixing
 (Zonalon)       with hydrocortisone, a combination especially
                 effective for genital pruritus. Use caution
                 in prescribing in combination with
                 antidepressants. Contraindicated for patients
                 with glaucoma or urinary retention. A 5%
                 cream formulation.
capsaicin        Less commonly used than other topicals. For
 (Zostrix)       localized pruritus, especially effective in
                 neurally induced pruritus (postherpetic
                 neuralgia). Don't use on atopic dermatitis.
                 OTC formulation; 0.075% cream.
INJECTABLE DRUGS
triamcinolone    Reserved for severe, very localized pruritus.
acetonide        Total dose depends on size of pruritic
 (Tac-3)         lesion. Risk of atrophy at injection site.
prednisolone     Another injectable steroid can be substituted.
acetate          Reserved for severe pruritus; considered
                 inappropriate for pruritus by some experts.
                 Risks tissue atrophy at injection site.
                 Several contraindications.
ORAL DRUGS
hydroxyzine      Top antihistamine because of high potency.
hydrochloride    Also works as an anxiolytic. Causes
                 drowsiness, which helps with pruritus that
                 interferes with sleep; use at bedtime.
                 Avoid high doses in patients with liver or
                 kidney disease or obstructed urination,
                 glaucoma. Contraindicated in early
                 pregnancy. Titrate to 75 mg or more if
                 needed.
diphenhydramine  Causes drowsiness; take at bedtime. Less
hydrochloride    expensive, somewhat less effective than
                 hydroxyzine. Avoid high doses in patients
                 with liver, kidney, or prostate disorders
                 or glaucoma; do not use with narcotics.
                 Titrate to 100 mg if needed.
doxepin          Strong antihistamine/antidepressant.
hydrochloride    Causes drowsiness; should be taken at
                 bedtime. Use with caution in cardiac
                 patients and those taking other
                 antidepressants. Remains in bloodstream
                 8-12 hours; adjust timing of dose to
                 prevent morning grogginess.
loratadine       Nonsedating antihistamines are usually
 (Claritin)      less useful for indication than
                 sedating antihistamines and cost more.
                 Could substitute cetirizine hydrochloride
                 (Zyrtec) or fexofenadine hydrochloride
                 (Allegra). Useful for generalized
                 pruritus associated with urticaria and
                 allergy.
prednisone       Another systemic steroid can be
                 substituted. Reserved for severe pruritus;
                 considered inappropriate for pruritus by
                 some experts. Several contraindications.
amitriptyline    Sedating antidepressant, especially
hydrochloride    effective in patients with psychiatric
                 component or neural itching--
                 postherpetic neuralgia. Do not use with
                 MAO inhibitors or just after myocardial
                 infarction. Titrate to 150 mg if needed.


(*.)Cost per indicated-size container of generic formulations, unless otherwise specified, is based on average wholesale price listed in the 1999 Red Book.

(**.)Cost is based on average wholesale price for 100-unit container of generic formulations, unless otherwise specified, in 1999 Red Book, except for prednisolone, for which cost is based on the average wholesale price of a 10-mL container of generic formulations in the 1999 Red Book.

(+.)The comments reflect the viewpoints and expertise of the following sources:

Dr. Timothy Berger, director of dermatology clinics, University of California, San Francisco.

Dr. Robert Kirsner, assistant professor of clinical dermatology, University of Miami.

Dr. Stefani Takahashi, clinical instructor of dermatology and staff dermatologist, University of California, Los Angeles.
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Author:Zoler, Mitchel L.; Bates, Betsy
Publication:Family Practice News
Article Type:Brief Article
Date:Mar 1, 2000
Words:1006
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