Table 1.

Representative inhibitors of P-gp and ABCG2

First generation	Cyclosporin A*, Verapamil*, Nifedipine*,†, Quinidine*, Quinine*, Tamoxifen*, Reserpine*,†, Prazosin*,†, Propafenone*,†, Erythromycin*, Itraconazole*,†, Ritonavir*,†, Benzquinamide*[23]
Second generation	Dexverapamil*, MM36*, Valspodar*,†, BIBW22BS*, Toremifene*, Quinine Homodimer (Q2)*, S9788*,†[23]
Third generation	Elacridar*,†, Tariquidar*,†, Zosuquidar*, Laniquidar*, Ontogen*, DP7*[23]
Fourth generation	Natural product derivatives: Flavonoids (Curcumin*[163], Apigenin*[164]), Polyphenols (Quercetin*[165], Resveratrol*,†[166]), Antimalarials (Chloroquine*,†[167]), Alkaloids (Galegine*[168], Nitensidine A*[169]), Fungal (Ko143†[170], Tryprostatin A†[171]), Chinese herbal medicines (Artemisinin*[172], Tetrandrine*[173]), Marine (Kendarimide* A, Sipholenol A*)[174] Repurposing FDA-approved drugs[175]: Imatinib*,†, Vardenafil*, Azithromycin*,†, Chlorpromazine*,† Peptidomimetics[23] Dual activity ligands[23]

^*P glycoprotein inhibitor

^†ABCG2 inhibitor.