erectile dysfunction

what is erectile dysfunction (ED)

sexual dysfunction that is defined as the inability to achieve or maintain an erection of penis during sexual activity

what are the causes of ED

• cardiovascular disease

• diabetes mellitus

• androgen deficiency

• hyperprolactinemia

• failure to initiate nerve impulse

• drug side effects e.g. thiazide diuretics

• smoking - contractile effect on smooth muscle

• alcohol

how does ED occur

how to treat ED - first line treatment

phosphodiesterase (PDE) type-5 inhibitors

what does PDE type 5 inhibitors do

temporarily increase blood flow to penis

what happens during penile erectile

• NO stimulates cGMP production in vascular smooth muscle of corpus cavernosum

• cGMP acts through intracellular athways to lower calcium intracellularly

• this causes relaxation of smooth muscles and penile arterial vessel dilation

true or false: PDE 5 is primary enzyme involved in breakdown of cGMP

true

structurally how do PDE5 inhibitors help treat ED

PDE5 inhibitors have similar structures to cGMP, competitively bind to enzyme and inhibit metabolism of cGMP

how does increased levels of cGMP help

• increased levels of cGMP cause increase penile blood flow and neurological function

examples of PDE5 inhibitors for treating ED

• sildenafil (Viagra)

• tadalafil (Cialis)

• vardenafil (Levitra)

• avanafil (Spedra)

note - the brand names are in brackets

how long does it take for sildenafil, vardenafil and avanafil to work

8 hours

how long does tadafil last for

36hours

side effects of PDE-5 inhibitors

• headaches, migraines

• flushing

• indigestion

• nausea and vomiting

• dizziness

what are some alternative treatments

• intracavernosal injections

• intraurethral pellets

• vacuum erectile devices

• surgery (penile prosthesis insertion)