vardenafil (Levitra, Staxyn)
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Introduction
Tradename: Levitra. New agent from Bayer. (2003)
Indications
- erectile dysfunction
- NO proof that vardenafil is better for patients with diabetes or after prostatectomy than sildenafil (Viagra)
- may work when Viagra does not[3]
Contraindications
- concurrent administration of nitrates[6] (or amyl nitrite)
- intermediate-high risk of coronary artery disease
- retinitis pigmentosa
- history of non-arteric ischemic optic neuropathy
Dosage
- 5-20 mg 25-60 minutes before intercourse
- start 10 mg & adjust to need
Tabs: 5, 10, 20 mg. (shelf-life 3 years)
- Staxyn: orally disintegrating tablets
Dosage adjustment in renal failure
- start 5 mg in patients with creatinine clearance < 30 mL/min
Pharmacokinetics
- rapidly absorbed after oral administration
- bioavailability is 15%
- high-fat meal can reduce aborption
- peak plasma levels in 30-120 minutes after oral dose
- volume of distribution 120 liters
- 95% bound to plasma proteins
- metabolized by cyt P450 3A4 & to a lesser extent cyt P450 3A5 & cyt P450 2C9
- elimination 1/2 life 4 hours
elimination via liver
protein binding = 95 %
Adverse effects
- see sildenafil (Viagra)
- hopes than it may not cause 'blue vision' problem[2]
- drug adverse effects of phosphodiesterase-5-inhibitors
- drug adverse effects of antihypertensive agents
Drug interactions
- concurrent administration of inhibitors of cyt P450 3A4 prolong 1/2 life of vardenafil
- potent inhibitors contraindicated
- erythromycin (diminish dose of vardenafil)
- grapefruit juice should be avoided
- concurrent administration nitrates {6] or amyl nitrite* contraindicated
- combined use with alpha-1 adrenergic antagonist increases risk of hypotension, especially orthostatic hypotension
- drug interaction(s) of nitrates with phosphodiesterase-5-inhibitors
- drug interaction(s) of phosphodiesterase-5-inhibitor with testosterone
- drug interaction(s) of phosphodiesterase-5-inhibitor with nitrates
- drug interaction(s) of phosphodiesterase-5-inhibitors with alpha-1-adrenergic receptor antagonists
- drug interaction(s) of NSAIDs & antihypertensives
Laboratory
Mechanism of action
- more selective than sildenafil (Viagra) for inhibition of phosphodiesterase-5.
- inhibition of PDE-5 > 15 fold PDE-6, > 130 fold PDE-1
* both phosphodiesterase-5 inhibitors & nitric oxide converge on the same pathway; both increase cGMP. Phosphodiesterase-5 inhibitors inhibit hydrolysis of cGMP. Nitric oxide activates guanylate cyclase increasing synthesis of cGMP
More general terms
Additional terms
References
- ↑ Prescriber's Letter 8(10):57 2001
- ↑ 2.0 2.1 Prescriber's Letter 10(9):49 2003
- ↑ 3.0 3.1 Prescriber's Letter 10(11):62 2003
- ↑ http://www.levitraguide.com
- ↑ Prescriber's Letter 18(8): 2011 COMMENTARY: New Vardenafil Formulation: Staxyn CHART: Phosphodiesterase 5 (PDE5) Inhibitor Interactions Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=270809&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ 6.0 6.1 Medical Knowledge Self Assessment Program (MKSAP) 19 American College of Physicians, Philadelphia 2022