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-17ß-
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
250°C
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