Table 3.

Summary of chemopreventive agents identified from the ClinicalTrials and PubMed databases.

Drug Class	Mechanism of Action	Drug	Route of Administration	Dose/Strength and Duration
Chemotherapy	Antimetabolite	5-Fluorouracil	Topical	5%; 4 weeks [42]
				5%; 2–4 weeks [44]
				5%; 4 weeks [43]
Retinoids	PAR inhibition	Acitretin	Oral	25 mg; 2 years [21]
Retinoids	PAR inhibition	Tretinoin	Topical	0.1%; 1.5–5.5 years [24]
Retinoids	PAR inhibition	Tazarotene	Topical	0.1%; 3 years [48]
NSAID	Anti-inflammation	Celecoxib	Oral	200 mg; 2 years [20]
				200 mg; 9 months [36]
NSAID	Anti-inflammation	Piroxicam	Topical	1%; 12 weeks [40]
NSAID	Anti-inflammation	Diclofenac	Topical	3%; 6 months [27]
NSAID	Anti-inflammation	Aspirin	Oral	81 or 325 mg; 3 years [39]
				100 mg; 5–7 years [37]
DFMO	Ornithine decarboxylase (ODC) inhibitor	Eflornithine	Topical	10%; 6 months [27]
				10%; 6 months [26]
Vitamin B3	DNA repair/inhibiting immunosuppression	Nicotinamide	Oral	500 mg; 12 months [32]
				500 mg; 6 months [33]
				500 mg; 12 months [35]
Vitamin D	Skin cell differentiation	Cholecalciferol	Oral	50,000 IU; 8–9 weeks [31]
Bacteriophage T4 endonuclease 5	DNA repair	T4N5	Topical	12-month; no results
Statin	Anti-inflammation	Lovastatin	Oral	40–80 mg; 6 months [49]
Anti-diabetic medication	PPARγ agonist	Pioglitazone	Oral	15–30 mg; 5½ months [51]
Anti-diabetic medication	Multiple	Metformin	Oral	2.8 years [47]
Anti-diabetic medication	Unknown	Sulfonylurea	Oral	2.8 years [47]
Limonene derivative	Unknown	Perillyl alcohol	Topical	0.3% or 0.76%; 12 weeks [18]
Psoriasis medication	FGF inhibitor	Potassium dobesilate	Topical	5%; 16 weeks [46]
Dietary supplement	Anti-inflammation	Omega-3	Oral	5 mg; 3 months [30]
Dietary supplement	Anti-inflammation	Sulforaphane	Oral	50, 100, or 200 μmol; 28 days [50]

PAR: retinoic acid receptors.