Avodart Pre-Surgery Hold Window: How Long to Stop Dutasteride Before an Operation

Does the Avodart label require a stop before surgery?

The Avodart prescribing information gives no preoperative stop interval. It lists no bleeding warning, and dutasteride 0.5 mg daily taken with warfarin for 3 weeks did not change warfarin pharmacokinetics or its effect on prothrombin time [1].

The one waiting period the label sets is 6 months: men treated with Avodart should not donate blood until at least 6 months after the last dose, to avoid giving dutasteride to a pregnant transfusion recipient [1]. That reflects the pharmacokinetics: terminal half-life about 5 weeks at steady state, with serum levels above 0.1 ng/mL for up to 4 to 6 months after the last dose [1].

What a pre-operative PSA looks like on dutasteride

Serum PSA falls by approximately 50% within 3 to 6 months of starting [1]. The label's rules for reading PSA on treatment: set a new baseline at least 3 months after starting; double an isolated value in a man treated 3 months or more; evaluate any confirmed rise from the lowest on-treatment value, even if still within the normal range for untreated men; percent free PSA needs no adjustment; and missed doses can affect results [1].

If the operation is prostate surgery or a biopsy

A randomized trial of a 5-alpha reductase inhibitor before prostate surgery tested finasteride, not dutasteride. Seventy men scheduled for transurethral resection of the prostate were randomized to finasteride 5 mg daily or placebo for 2 weeks; among the 68 who had surgery, mean blood loss in irrigation fluid was lower with finasteride: 43.6 versus 69.3 g of hemoglobin, P=0.011 [2]. That trial does not establish a preoperative dutasteride hold or benefit. Around prostate procedures, the label's PSA guidance is the doubling rule and evaluation of any confirmed rise from the lowest on-treatment value [1].

Jalyn and cataract surgery

The Avodart label describes combination treatment as Avodart 0.5 mg once daily plus tamsulosin 0.4 mg once daily [1]. Jalyn is the fixed-dose capsule containing dutasteride 0.5 mg and tamsulosin 0.4 mg. Dutasteride is a 5-alpha-reductase inhibitor, not an alpha blocker [1].

In a retrospective review of 511 cataract patients, intraoperative floppy iris syndrome occurred in 10 of 16 patients taking tamsulosin (63%) and in none of 11 taking other alpha-1 blockers; overall 2.0% of the 511 patients had it [4]. This evidence concerns tamsulosin, not dutasteride.