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    Summary for UKPID



    Finasteride




    Dr Alan Worsley Bsc(hons) PhD MRPharmS

    National Poisons Information Service (Newcastle Centre)
    Regional Drug & Therapeutics Centre
    Wolfson Building
    Claremont Place
    Newcastle upon Tyne
    NE1 4LP
    UK


    This monograph has been produced by staff of a National Poisons
    Information Service Centre in the United Kingdom.  The work was
    commissioned and funded by the UK Departments of Health, and was
    designed as a source of detailed information for use by poisons
    information centres.

    Peer review group: Directors of the UK National Poisons Information
    Service.


    FINASTERIDE (Poscar(R))

    Summary

    Type of product

         anti-androgen

    Ingredients

         tablets - 5 mg

    Toxicity

         Fatal dose not known

    Features

         Not known

         Side effects reported include impotence, decreased libido and
         ejaculate volume, breast tenderness and enlargement,
         hypersensitivity reactions (including lip swelling and rash).

    Management

    1.   If ingestion is within 2 hours 50 - 100 grams (adults) or 25 - 50
         grams (children) of oral activated charcoal may be administered.
         Lactulose (20 ml) should be given to prevent constipation. There
         is no data to indicate whether this is effective in finasteride
         poisoning.

    2.   Symptomatic measures as indicated by the patients clinical
         condition.

    References

    ABPI Data Sheet Compendium. Datapharm Publications Limited. 1996-1997.

    British National Formulary. Number 32 (September 1996). British
    Medical Association and Royal Pharmaceutical Society.

    Dollery C. Therapeutic Drugs. (Suppl 2), Churchill Livingstone. 1994

    FINASTERIDE

    Brand name

         Proscar(R)

    Generic name

         finasteride

    Chemical group/family

         Anti-androgen
         BNF 6.4

    Reference number

         (CAS) 98319-26-7

    Manufacturer/supplier

         Merck Sharp & Dohme Ltd
         Hertford Road
         Hoddesdon
         Herts EN11 9BU

         Tel: 01992 467272
         Fax: 01992 451066

    Presentation

         finasteride 5 mg tablets
         pack size 28 tablets

    Physicochemical properties: (Dollery)

         N- (1,11-Dimethyethyl)-3-oxo-4-aza-5alpha-androst-1-ene-17-
         carboxamide

    Physical properties
         Off-white, crystalline solid

    Molecular Weight
         372.6

    pKa
         -

    Solubility
         in alcohol     freely soluble
         in water       very slightly soluble

    Octanol/water partition coefficient
         > 1.258

    Melting point
         250C

    USES

    Indications

    Treatment and control of benign prostatic hyperplasia (BPH) to control
    regression of the enlarged prostate, improve urinary flow, and improve
    symptoms associated with BPH.

    Therapeutic Dosage (BNF)

    Adults:          5 mg daily, review treatment after 6 months 

    Children:        finasteride is contra-indicated

    Elderly:         no dosage adjustment is required

    Renal failure:   dosage adjustment not necessary as pharmacokinetic
                     studies do not indicate any change in the deposition
                     of finasteride.

    Hepatic failure:    no data available

    Contraindications

    Hypersensitivity to any component of the product
    Women who are or may become pregnant
    Children

    Precautions

    Obstructive uropathy, prostate cancer (may decrease markers such as
    prostate specific antigen)

    As finasteride is excreted in the semen adequate contraceptive
    measures (barrier methods) should be taken.

    Women of child bearing age should avoid handling crushed or broken
    tablets.

    Pharmacokinetics: (Dollery)

    Oral absorption          100%
    Presystemic metabolism   < 20%
    Volume of distribution   75 l
    Plasma protein binding   93%

    Plasma half life
         range               4.7 - 7.1 hr
         mean                6 hr

    Toxicokinetics

         none available

    Adverse effects (Data Sheet)

    Decreased libido (3.3%), impotence (3.7%), and decreased volume of
    ejaculate (2.8%)
    have been reported in patients receiving 5 mg of finasteride daily for
    12 months.

    Breast tenderness and enlargement

    Hypersensitivity reactions including lip swelling and skin rash

    Pregnancy (Data Sheet)

    Finasteride is contra-indicated in women who are or may become
    pregnant. Because of the ability of 5 alpha reductase inhibitors to
    inhibit conversion of testosterone to dihydrotestosterone, these
    drugs, including finasteride, may cause abnormalities of the external
    genitalia of a male fetus when administered to a pregnant woman.

    In animal developmental studies, hypospadias were observed in the male
    offspring of pregnant rats given finasteride at doses ranging from 100
    mcg/kg/day to 100 mg/kg/day, at an incidence of 3.6% to 100%.
    Additionally, pregnant rats provide male offspring with decreased
    prostatic and seminal vesicular weights, delayed preputial separation,
    transient nipple development and decreased anogenital distance when
    given finasteride at doses below the recommended human dose. The
    critical period during which these effects can be induced has been
    defined in rats as days 16-17 of gestation.

    No effects were seen in female offspring exposed in utero to any dose
    of finasteride.

    Exposure to finasteride - risk to male fetus: Crushed or broken
    finasteride tablets should not be handled by women who are or may
    become pregnant because of the possibility of absorption of
    finasteride and the subsequent risk to the male fetus.

    Similarly, small amounts of finasteride have been recovered from the
    semen in subjects receiving finasteride 5 mg/day. It is not known
    whether a male fetus may be adversely affected if his mother is
    exposed to semen of a patient being treated with finasteride.

    Therefore, the patients' sexual partner should either avoid exposure
    to her partners semen (e.g. by use of condom) or he should discontinue
    finasteride.

    Breast milk

    Finasteride is not indicated for use in women. It is not known whether
    finasteride is excreted in human milk.

    Interactions (BNF)

    No clinically important interactions reported

    EPIDEMIOLOGY OF POISONING

    No specific data or case reports of finasteride poisoning are
    available.

    Patients have received single doses of finasteride up to 400 mg and
    multiple doses of finasteride up to 80 mg daily for up to 3 months and
    40 mg daily for 24 weeks without any adverse effects. (Dollery)

    Side effects reported at therapeutic dosage include:

    Decreased libido (3.3%), impotence (3.7%), and decreased volume of
    ejaculate (2.8%) have been reported in patients receiving 5 mg of
    finasteride daily for 12 months (Prod Info Proscar, 1992).

    Breast tenderness and enlargement

    Hypersensitivity reactions including lip swelling and skin rash

    MANAGEMENT

    update date: January 1997

    No specific details available

    Decontamination

    If ingestion is within 2 hours 50 - 100 grams (adults) or 25 - 50
    grams (children) of oral activated charcoal may be administered.
    Lactulose (20 ml) should be given to prevent constipation. There is no
    data to indicate whether this is effective in finasteride poisoning.

    Supportive care

    General supportive care should be given

    Monitoring

    As no data is available on finasteride poisoning vital signs should be
    monitored - pulse blood pressure, respiration

    Antidotes

    There are no specific antidotes

    Elimination techniques

    No data available.

    Investigations

    No data is available on finasteride poisoning, but routine
    investigations including renal function tests, urinalysis and
    electrolytes could be carried out.

    Case Data

    update date: January 1997
    No data available

    Other Toxicological Data

    No data available

    Ecotoxicological Data

    No data available

    Biodegradation

    No data available

    Hazard Warnings

    No data available

    Waste disposal Data

    No data available

    Author

    Dr Alan Worsley Bsc(hons) PhD MRPharmS

    National Poisons Information Service (Newcastle Centre)
    Regional Drug & Therapeutics Centre
    Wolfson Building
    Claremont Place
    Newcastle upon Tyne
    NE1 4LP
    UK

    This monograph was produced by the staff of the Newcastle Centre of
    the National Poisons Information Service in the United Kingdom. The
    work was commissioned and funded by the UK Departments of Health, and
    was designed as a source of detailed information for use by poisons
    information centres.

    Peer review was undertaken by the Directors of the UK National Poisons
    Information Service.

    Last updated January 1997

    REFERENCES

    ABPI Data Sheet Compendium. Datapharm Publications Limited. 1996-1997.

    British National Formulary. Number 32 (September 1996). British
    Medical Association and Royal Pharmaceutical Society.

    Dollery C. Therapeutic Drugs. (Suppl 2), Churchill Livingstone. 1994
    


    See Also:
       Toxicological Abbreviations