Inclusion criteria:

• Rationale - The vertex area of the scalp will be evaluated during this study, therefore the inclusion criterion of Norwood Hamilton areas IIIv, IV or V ensures that subjects with vertex hair loss will be recruited in line with the primary efficacy endpoint of change in hair growth in the vertex.

A subject will be eligible for inclusion in this study only if all of the following criteria apply:

1. Male out-patients aged 18-49 years, inclusive
2. Diagnosis of Male Pattern Hair Loss classified as type IIIv, IV, or V utilising the modified Norwood-Hamilton classification (N.B. types IVa and Va are excluded)
3. Able to comprehend instructions and record required information
4. Will provide signed and dated written informed consent to participate in this investigation

Exclusion criteria:

• A subject will not be eligible for inclusion in this study if any of the following criteria apply:
• Evidence of hypogonadism defined as serum testosterone < 250ng/dl and/or LH >20mIU/ml Note: If the initial serum testosterone result is < 250ng/dl and the LH value is normal, the test may be repeated once. Attempts should be made, where possible, to collect all samples in the morning hours. If the repeat testosterone result is < 250ng/dl, the subject is not eligible for participation.
• Greater than two times the upper limit of normal for ALT or AST, or a bilirubin greater than 2.0mg/dl (exception - subjects diagnosed with Gilbert's syndrome will be eligible to participate in the study)
• Serum creatinine >1.8mg/dl
• Global scalp hair thinning, including occipital areas
• Scarring of the scalp or any other condition or disease of the scalp or hair, including diseases of the hair shaft (e.g., uncontrolled seborrheic dermatitis, tinea infections, other causes of alopecia, prior hair transplants or scalp reductions, psoriatic dermatitis) and inability to discontinue use of hair weaving.
• Subjects who use hair colourants/hair dyes, or have the remaining traces of colourants in their hair. Subjects must maintain their natural hair colour throughout the study.
• Hair length in non-balding areas ≤2cm (3/4 inch) around the vertex region of the head. Subjects must maintain the same hairstyle throughout the study.
• History of malignancy within the past five years, except basal cell or squamous cell carcinoma of the skin
• Serum PSA level > 2.0 ng/ml at screening visit.
• Family history(Father, brothers) of prostate cancer.
• Active unstable thyroid disease, including subjects on therapy for either hyperthyroidism or hypothyroidism unless their dose of thyroid medication has been stable for 3 months and serum TSH is normal
• Hypersensitivity to any 5 AR inhibitor or drugs chemically related to the study medication
• Use of finasteride or other 5 AR inhibitors within the 12 months prior to screening.
• Previous use of dutasteride.
• Use of phytotherapy (e.g. saw palmetto) within 8 weeks prior to screening.
• Previous use of cytotoxic agents
• Use of glucocorticoids (inhaled glucocorticoids are allowed; topical steroids are allowed provided that they are not used on the scalp) within the 3 months prior to screening

• Use of the following during the 6 months prior to screening:

  • Minoxidil (oral or topical)
  • Drugs with anti-androgenic properties (e.g., cyproterone acetate, spironolactone, ketoconazole, flutamide, bicalutamide). Cimetidine cannot be used during the study but is not an excluded drug when used during the previous 6 months.
  • Topical estrogen, progesterone
  • Tamoxifen
  • Drugs potentially causing hypertrichosis (e.g., cyclosporine, diazoxide, phenytoin psoralens)
  • Anabolic steroids
  • Lithium and phenothiazines
• Concurrent or regular use during the 4 weeks prior to screening of topical agents to the scalp (e.g., anti-inflammatories)

• Participation in any investigational or marketed drug trial within 30 days preceding the screening phase of this study. Participation in any other drug trial during the course of this study including the follow-up period.

  21. History or current evidence of drug or alcohol abuse within the 12 months prior screening

• History of any illness (including psychiatric) which may impair the ability to provide informed consent or comply with study requirements
• History of any unstable illness or condition that, in the opinion of the investigator, might confound the results or put the subject at risk.
• Subjects who are known to be HIV positive (status which includes subjects with AIDS)
• Subjects who will not refrain from donating blood until completing the study follow-up period.