Systemic and metabolic effects of PDE5-inhibitor drugs

Table 1 Pharmacological profile of oral PDE5-i at therapeutic dosage for ED

Parameter	Sildenafil 100 mg	Tadalafil 20 mg	Vardenafil 20 mg
Tmax (h)	1.16 ± 0.99	2	0.66 (0.250-3.0)
T1/2 (h)	3.82 ± 0.84	17.5	3.94 ± 1.31
C (max ng/m)	327 ± 236	378	20.9 ± 1.83
AUC (ng × h/m)	1963 ± 859	8066	74.5 ± 1.82

PDE5-i: Phosphodiesterase type-5 inhibitor; ED: Erectile dysfunction.

Table 2 In vitro enzymatic inhibition activity of the marketed PDE5-i (IC50 nmol/L)

PDE isoform	Sildenafil	Tadalafil	Vardenafil
PDE-1	60	> 10 000	257
PDE-2	> 10 000	> 10 000	> 10 000
PDE-3	2 600	> 10 000	3 600
PDE-4	1 800	> 10 000	5 700
PDE-5	3.8	1	0.7
PDE-6	7.4	780	15.7

Table 3 Causes and main interventions in endothelial dysfunction

Factors associated with endothelial dysfunction	Interventions to correct endothelial dysfunction
Aging	L-arginine
Male sex	Estrogens
Cigarette smoking	Smoking cessation
History of CHD	Antioxidants
Low HDL- and high LDL-COL	Statins
Hypertension	ACE-i
Hyperomocysteinemia	Homocysteine lowering (folates)
Diabetes/obesity	Exercise
Erectile dysfunction	PDE5-i