Drugs for Benign Prostatic Hyperplasia

Question 1

Short-Acting Selective α-1 Blockers Drugs:

Answer 1

Prazosin

Alfuzosin

Question 2

PDE-5 Inhibitors Drugs:

Answer 2

Tadalafil

Question 3

Long-Acting Selective α-1 Blockers Drugs:

Answer 3

Terazosin

Doxazosin

Question 4

5-Alpha Reductase Inhibitors Drugs:

Answer 4

Finasteride

Dutasteride

Question 5

α-1a–partially Selective Blockers Drugs:

Answer 5

Tamsulosin

Silodosin

Question 6

Benign Prostatic Hyperplasia (BPH) originates in?

Answer 6

The transition zone of the prostate, surrounding the proximal urethra. Untreated prostatic enlargement can block urine flow and cause bladder, urinary tract or kidney problems.

Question 7

α-1a overwhelmingly predominate in?

Answer 7

Normal human prostatic stroma with α-1d present to a lesser extent.

Question 8

α-1a predominates:

Answer 8

Penile Urethra
Prostate Gland
Prostate Urethra
Trigone of Bladder

Question 9

α-1d predominates:

Answer 9

Bladder detrusor muscle

Urinary bladder

Question 10

Prazosin
Metabolism/Elimination
Half life
Bioavailability

Answer 10

Demethylation; conjugation; fecal elimination
2-4 hrs
90%

Question 11

Alfuzosin
Metabolism/Elimination
Half life
Bioavailability

Answer 11

3A4; fecal/renal elimination (3:1)
10 hr
50%

Question 12

Terazosin
Metabolism/Elimination
Half life
Bioavailability

Answer 12

Hepatic-fecal/renal elimination (3:2)
12 hr
~100%

Question 13

Doxazosin
Metabolism/Elimination
Half life
Bioavailability

Answer 13

3A4>2D6, 2C19. Fecal elimination predominantly
15-22 hrs
55-65%

Question 14

Tamsulosin
Metabolism/Elimination
Half life
Bioavailability

Answer 14

3A4 & 2D6; renal/fecal (3:1)
5-15 hrs
>90%; decrease by food

Question 15

Silodosin
Metabolism/Elimination
Half life
Bioavailability

Answer 15

3A4; glucuronide conj; fecal/urine (2:1)
13 hr
32%

Question 16

α-1 Blockers Issues & Sidee Effects:

Answer 16

ALL of these drugs have comparable efficacy
Common side effects include:
GI: xerostomia, nausea
CNS: dizziness, somnolence, asthenia, headache, insomnia

Question 17

Advantage of selective (α-1a) agents:

Answer 17

No need for dose titration (Diminished effects on CV function)

Question 18

Disadvantage of α-1a agents:

Answer 18

– Abnormal (retrograde) (anejaculation) ejaculation
– 9-18%, tamsulosin; ≤ 28%, silodosin
– Block of dopamine and other regulatory CNS transmitters

Question 19

The superior alpha blocker currently available for treating BPH &why?

Answer 19

Alfuzosin 10 mg because it achieves clinically significant improvements in LUTS & has no significant effects on dizziness, asthenia, & ejaculatory dysfunction.

Question 20

Occasional adverse event in patient taking alpha-1 blockers?

Answer 20

During cataract surgery in patients taking any of the alpha-1 blockers can experience Floppy Iris Syndrome.

Question 21

Floppy Iris Syndrome

Answer 21

Characteristics:
– flaccid iris that billows in response to intraoperative irrigation
– progressive intraoperative miosis despite dilation with standard mydriatic drugs
– potential prolapse of the iris toward the phacoemulsification incisions

Question 22

Tadalafil Relief of BPH most likely occurs via?

Answer 22

s.m. relaxation

Comparable to corpus cavernosum effect in erectile dysfunction.

Question 23

Tadalafil adverse effects uncommon, notably:

Answer 23

– Headache, nausea, indigestion, nasopharyngitis, upper respiratory tract infections
– More rare: non-arteritic ischemic optic neuropathy; retinal artery occlusion; hearing loss

Question 24

Tadalafil Contraindication:

Answer 24

Concurrent organic nitrates:
– Profound hypotension
– Exacerbated by alcohol consumption

Question 25

Finasteride: Mechanism

Answer 25

Type 2 5-α reductase enzyme

Question 26

Dutasteride: Mechanism:

Answer 26

type 1 & 2 5-α reductase enzyme

Question 27

Finasteride & Dutasteride Adverse Effects

Answer 27

Both cat. X; not carried in semen. Well tolerated; low incidence of adverse effects including ejaculation dysfunction; erectile dysfunction; decrease libido; gynecomastia. Decreases PSA levels