Drugs For Erectile Dysfunction Flashcards

1
Q

Drugs for ED:

Prostaglandin E1

A

Alprostadil

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2
Q

Drugs for ED:

Alpha- adrenoreceptor antagonists

A

Phentolamine
Yohimbine

Replaced by efficacious, safe, and easy to use PDE5 inhibitors

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3
Q

Drugs for ED:

Others

A

Methyltestosterone- use limited to men with hypo gonadal impotence
Trazodone- a SSRI antidepressant agent with alpha- adrenoreceptor blocking properties- priapism side effect- enhance libido & prolongs nocturnal erections

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4
Q

PDE5 inhibitors MOA

A

Selectively inhibit PDE5- increases cGMP- increase SM relaxation- increase sinusoidal compliance- increase engorgement of penis with blood- INCREASE erection
Treatment of pulmonary hypertension

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5
Q

PDE5 inhibitor contraindication

A

Patients taking organic nitrate vasodilators (e.g. isosorbid dinitrate or nitroglycerin)
Dosage adjustments in patients with hepatic dysfunction and CYP3A4 inhibiting drugs (clarithromycin, erythromycin)

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6
Q

PDE5 inhibitor adverse effects

A

Headaches, flushing due to cerebral & cutaneous effects respectively
Inhibit PDE6 isoform- color vision disturbances (loss of blue/green discrimination)
Nasal congestion
Dyspepsia
Sildenafil & tadalafil also inhibit PDE1 & PDE11 isoforms, respectively; these PDE’s play a role in sperm development & function

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7
Q

PDE5 inhibitors drug interaction

A

Co-administration with NO donor (e.g. nitroglycerin- potentially catastrophic hypotension)
CYP3A4 inhibiting drugs (clarithromycin, erythromycin)

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8
Q

PDE5 time to peak, half life & food interactions

A

Peak concentration:
Sildenafil- 60 min.
Vardenafil- 60
Tadalafil- 120

Half life:
Sildenafil- 3-4hrs.
Vardenafil- 4-5
Tadalafil- 18

Food interaction:
Sildenafil- Yes
Vardenafil- Yes
Tadalafil- No

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9
Q

Yohimbine MOA

A

Alpha-2 adrenoreceptor antagonist
Indolealkylamine alkaloid found in bark of the plant Pausinystalia yohimbe and in root of Rauwalfia spp
Relatively selective alpha-2 antagonist
Stimulation of NE receptors in locus coeruleus- central activation of sexual arousal
Blockade of central alpha-2 autoreceptors- increased NE release centrally- increased sexual arousal
Antagonizes 5-HT1 & 5-HT2A- increased mood (antidepressant & aphrodisiac properties- leads to erection)

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10
Q

Phentolamine MOA

A

Alpha-2 adrenoreceptor antagonist

Competitive alpha-1/2 antagonist- increased penile vasodilation- increased penile blood flow- leads to erection

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11
Q

Beta blockers

A

High blood pressure medications

Propranolol

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12
Q

Alpha-2 adrenoreceptor agonist

A

High blood pressure medication

Clonidine

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13
Q

Adrenergic neuron blockers

A

High blood pressure medication

Guanethidine

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14
Q

ACE inhibitors

A

High blood pressure medication

Captopril

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15
Q

Calcium channel blockers

A

High blood pressure medication

Nifedipine

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16
Q

Diuretics

A

High blood pressure medications

Hydrochlorothiazide

17
Q

Recreational drugs causing impotence

A

Alcohol

Cocaine

18
Q

Antidepressant medication causing impotence

A

Fluoxetine

19
Q

Psychiatric medication causing impotence

A

Chlorpromazine

20
Q

Alprostadil

A

Prostaglandin E1
Not orally effective; intra-cavernous injection- complete/partial erection (1-3 hrs.)
Activates EP receptors- increased cAMP; relaxation of cavernosal smooth muscle, & erection

21
Q

Apomorphine

A

Short acting central & peripheral D1/D2 receptor agonist; increase erection in normal & ED men
Stimulates central D1/D2 receptors- increase sexual pleasure reward system
Two sites of action- para ventricular nucleus & nucleus accumbens

22
Q

Papaverine

A

Nonspecific PDE inhibitor- increase cAMP & cGMP
An opium alkaloid vasodilator with unclear mechanism of action
Selective PDE10A subtype inhibitor; given by intra-cavernous injection to produce erection
Effective in men with psychogenic & neurogenic ED; less effective in vasculogenic ED

23
Q

Drugs for ED:

PDE5 inhibitors

A

Sildenafil (Viagra)
Tadalafil (Cialis)
Vardenafil (Levitra)

24
Q

Cyclic AMP selective

A

PDE-4- Clinically relevant for immune and inflammatory cells

25
Q

PDE5 metabolism

A

Metabolized in liver by CYP3A4 enzymes