Erectile Dysfunction in the Elderly: An Old Widespread Issue with Novel Treatment Perspectives

Table 1

Some examples on potential interactions among PDE5I and other drugs via CYP450.

Cytochrome	Substrates	Inhibitors	Inductors
CYP1A2	PDE5I: sildenafil; Antidepressants: tricyclics, fluvoxamine, mirtazapine; Antipsychotics: haloperidol, olanzapine, clozapine; Methylxantines: caffeine, teophylline; Other drugs: R-warfarin, tacrine, paracetamol	Ciprofloxacin; Fluvoxamine	Barbiturates; Carbamazepine; Phenytoin; Rifampicin; Tobacco
CYP3A4	PDE5I: sildenafil, tadalafil, vardenafil,; Antidepressants: tricyclicics, venlafaxine, citalopram, mirtazapine; Benzodiazepines: diazepam, bromazepam; Nonbenzodiazepine anxyolitics: buspirone; Antipsychotics: haloperidol, clozapine, risperidone, ziprasidone, sertindole, quetiapine, aripiprazole; Anticonvulsants: carbamazepine, felbamate, tiagabine; Calcium-antagonistis: nifedipine, diltiazem, verapamil; Other drugs: amiodarone, quinidine, terfenadine, astemizole, macrolides (erythromicin, clarithromycin), tamoxifen, cyclosporine,	Antiarrhytmics: quinidine, amiodarone; Antifungal drugs (fluconazole, itraconazole, ketoconazole); Antidepressants: fluvoxamine, fluoxetine, nefazodone; Antihistamines: loratadine; Antiviral drugs: indinavir, ritonavir; Grapefruit juice (at least 250 mL); Macrolides: clarithromycin; Erythromicin; Calcium channel blockers: diltiazem, verapamil; Proton pump inhibitors: omeprazole,; testosterone	Barbiturates; Carbamazepine; Felbamate^∗; Hypericum; Oxcarbazepine^∗; Phenytoin; Rifampicin; Topiramate^∗; *Weak enzymatic inductor

∗refers to the activity of felbamate, oxcarbazepine and topiramate as weak enzymatic inductors.