Serendipity in anticancer drug discovery

Table 2 List of drugs discovered by serendipitous events in the laboratory and their derivatives

Serendipitous drugs	Derivatives	No. of derivatives
Acetanilide	Acetaminophen	1
Acetohexamide	Tolbutamide, glimepiride, glibenclamide, glipizide, chlorpropamide, gliquidone, tolazamide, gliclazide	8
Captopril	Ramipril, fosinopril, lisinopril, trandolapril, enalapril, perindopril, spirapril, quinapril	8
Cisplatin	Oxaliplatin, carboplatin	2
Diethylstilbestrol	Dienestrol	1
Digoxin	Digitoxin, deslanoside, acetyldigitoxin, ouabain	4
Ergotamine	Dihydroergotamine, dihydroergotoxine, ergoloidmesylate, methysergide, methylergonovine, ergonovine	6
Ephedrine	Pseudoephedrine, ritodrine, metaraminol, phenylephrine, isoetharine, fenoterol, epinephrine, orciprenaline, terbutaline	9
Griseofulvin	NA	0
Heparin	Pentosan, polysulfate, enoxaparin, ardeparin, fondaparinux sodium	4
lsoniazid	NA	0
Lidocaine	Prilocaine, tocainide, mepivacaine, bupivacaine, levobupivacaine, ropivacaine	6
Lithium	NA	0
Marinol	Nabilone	1
Mechlorethamine	Chlorambucil, cyclophosphamide, melphalan, uracil mustard, estramustine	5
Mecillinam	Pivmecillinam	1
Methotrexate	Leucovorin	1
Nalidixic acid	Rosoxacin, enoxacin, pefloxacin, norfloxacin, lomefloxacin, ciprofloxacin, levofloxacin, ofloxacin	8
Nitroglycerine	Erythrityl tetranitrate, Isosorbide dinitrate	2
Penicillin	Ampicillin, amoxicillin, azidocillin, azlocillin, bacampicillin, carbenicillin, cloxacillin, cyclacillin, dicloxacillin, flucloxacillin, hetacillin, meticillin, mezlocillin, nafcillin, oxacillin, penicillin g, penicillin V, piperacillin, pivampicillin, tazobactam, ticarcillin	21
Pentamidine	NA	0
Physostigmine	NA	0
Quinine	Quinidine	1
Sorafenib	NA	0
Streptomycin	Framycetin, neomycin, josamycin, tobramycin, kanamycin, candicidin, spectinomycin	7
Sulfanilamide	Silver sulfadiazine, sulfacetamide, sulfacytine, sulfadiazine, sulfadimethoxine, sulfadoxine, sulfamerazine, sulfamethizole, sulfametopyrazine, sulfamethoxazole, sulfamoxole, sulfapyridine, sulfisoxazole	13
Valproic acid	Divalproex sodium	1
Vinblastine	Vincristine, vindesine, vinorelbine	3
Dicoumarol	NA	0
Warfarin	Acenocoumarol, phenprocoumon, dicumarol	3
Zinc Sulfate	NA	0

NA: Not available.