Dosing and uses of Rapaflo (silodosin)
Adult dosage forms and strengths
capsule
- 4mg
- 8mg
Benign Prostatic Hyperplasia
8 mg PO qDay
Administration: Take with meaL
Renal Impairment
CrCl <50 mL/min: Dose adjustment not necessary
CrCl 30-50 mL/min: 4 mg PO qDay
CrCl <30 mL/min: Contraindicated
Hepatic Impairment
Mild-to-moderate impairment (Child-Pugh class A or B): Dose adjustment not necessary
Severe Impairment: (Child-Pugh class C): Contraindicated (not studied)
Pediatric dosage forms and strengths
Not indicated
Rapaflo (silodosin) adverse (side) effects
>10%
Retrograde ejaculation (28%)
1-10%
Diarrhea (3%)
Headache (2%)
Insomnia ((1-2%)
Dizziness (3%)
Orthostatic hypotension (3%; increased in patients >65 years)
Nasopharyngitis (2%)
Nasal congestion (2%)
Sinusitis (1-2%)
Postmarketing Reports
Skin and subcutaneous tissue disorders: Toxic skin eruption, purpura, skin rash, pruritus, urticaria
Hepatobiliary disorders: Jaundice, impaired hepatic function associated with increased transaminase values
Immune system disorders: Allergic-type reactions, not limited to skin reactions including angioedema
Genitourinary system: Priapism
Warnings
Contraindications
Hypersensitivity
Severe renal impairment (CrCl <30 mL/min)
Severe hepatic impairment (Child-Pugh Score >10)
Concomitant strong CYP3A4 inhibitors or P-glycoprotein inhibitors
Cautions
Renal impairment, cataract surgery (potential risk of Intraoperative Floppy Iris Syndrome)
Rule out prostate cancer prior to treatment
Risk of orthostatic hypotension with or without syncope with first dose
Additive blood pressure lowering effects and symptomatic hypotension can result from concomitant administration of PDE-5 inhibitor (eg, sildenafil, tadalafil, vardenafil)
Use with caution in patients with mid-to-moderate hepatic impairment
Use with caution in the elderly (risk of hypotension)
Not indicated for use in women or children
Not for use as hypertensive
Pregnancy and lactation
Pregnancy category: B; not indicated in women
Lactation: Unknown if distributed in breast milk; not indicated in women
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Rapaflo (silodosin)
Mechanism of action
Selective antagonist of postsynaptic alpha-1-adrenoceptors; blocking the alpha1A-adrenoreceptors in the smooth muscle of the prostate leads to relaxation of the smooth muscle in the bladder neck and prostate causing an improvement of urine flow and decreased symptom of BPH.
Pharmacokinetics
Time: 2.6 +/- 0.9 hr
Concentration: (8mg dose) 62 ng/mL
Bioavailability: 32%
Half-Life: 13 +/- 8 hr
Protein Bound: 97%
Vd: 49.5 L
Clearance: 10 L/hr
Metabolism: glucuronidation, alcohol & aldehyde dehydrogenase, CYP3A4
Excretion: feces & urine
