Tamsulosin with dutasteride

How it works

Tamsulosin relaxes prostatic and bladder-neck smooth muscle via selective alpha-1A adrenoceptor blockade, while dutasteride inhibits type-1 and type-2 5-alpha-reductase to lower dihydrotestosterone and shrink the prostate.

Prescribing in practice

• Dutasteride is teratogenic and absorbed through skin, so the capsules must not be handled by women who are or may become pregnant, and treated men should not donate blood during therapy and for a defined period afterwards.
• Tamsulosin can cause first-dose and postural hypotension and intra-operative floppy iris syndrome, so cataract surgeons must be told the patient is taking it.
• Dutasteride approximately halves prostate-specific antigen, and this must be accounted for when interpreting PSA for prostate cancer screening.

Monitoring

Monitor symptom response, postural blood pressure and PSA trends interpreted against the expected dutasteride-related reduction.

Counselling the patient

• Women who are or could become pregnant must not handle the capsules.
• Rise slowly to avoid dizziness, and tell your eye surgeon you take this before any cataract operation.

Evidence & guidelines

The CombAT trial showed combined tamsulosin and dutasteride reduced symptom progression and acute urinary retention more than either agent alone in larger prostates.