Loratadine, an H₁ Antihistamine, Inhibits Melanogenesis in Human Melanocytes

Table 1

Summary of the H1 antihistamines screened for antimelanogenesis. Among them, clemisole, ebastine, loratadine, and terfenadine significantly decreased the melanin content (text with ).

Name	Trade name	Therapeutic chemical class	Systematic (IUPAC) name	Molecular weight
First generation antihistamines
Brompheniramine maleate	Bromfed, Dimetapp, Bromfenex, Dimetane, Lodrane	Alkylamine	3-(4-bromophenyl)-N,N-dimethyl-3-pyridin-2-yl-propan-1-amine	435.3213
Chlorpheniramine maleate	Chlor-trimeton	Alkylamine	3-(4-chlorophenyl)-N,N-dimethyl-3-pyridin-2-yl-propan-1-amine	390.8703
Clemastine fumarate	Tavist	Aminoalkyl ethers	(2R)-2-2-[(1R)-1-(4-chlorophenyl)-1-phenylethoxy]ethyl-1-methylpyrrolidine	459.9746
Clemizole hydrochloride	-	-	1-[(4-chlorophenyl)methyl]-2-(pyrrolidin-1-ylmethyl)benzimidazole	362.3053
Diphenhydramine hydrochloride	Benadryl, unisom, sominex, zzzquil	Aminoalkyl ethers	2-(diphenylmethoxy)-N,N-dimethylethanamine	291.824
Doxylamine succinate	unisom	Aminoalkyl ethers	(RS)-N,N-dimethyl-2-(1-phenyl-1-pyridin-2-yl-ethoxy)-ethanamine	388.4677
Methapyrilene hydrochloride	-	Substituted ethylenediamines	N,N-dimethyl-N′-pyridin-2-yl-N′-(2-thienylmethyl)ethane-1,2-diamine	297.8526
Orphenadrine hydrochloride	Norflex, Banflex, Orphenate, Flexoject, Flexon	Aminoalkyl ethers	N,N-dimethyl-2-[(2-methylphenyl)- phenyl-methoxy]-ethanamine	305.8511
Pheniramine maleate	Avil	Substituted alkylamines	N,N-dimethyl-3-phenyl-3-pyridin-2-yl-propan-1-amine	356.4253
Promethazine hydrochloride	Phenergan	Phenothiazine derivatives	(RS)-N,N-dimethyl-1-(10H-phenothiazin-10-yl)propan-2-amine	320.8873
Pyrilamine maleate	Pyrlex	Substituted ethylene diamines	N-(4-methoxybenzyl)-N′,N′-dimethyl-N-pyridin-2-ylethane-1,2-diamine	401.4664
Triprolidine hydrochloride	Actidil, Myidil, Actifed	other	2-[(E)-1-(4-methylphenyl)-3-pyrrolidin-1-yl- prop-1-enyl]pyridine	314.8616
Second generation antihistamines
Ebastine	Evastin, kestine, ebastel, aleva, ebatrol	Other	4-(4-benzhydryloxy-1-piperidyl)-1-(4-tert-butylphenyl)butan-1-one	469.6731
Cetirizine dihydrochloride	Zirtec, Zyrtec, reactine	Piperazine derivatives	(±)-[-[-[(4-chlorophenyl)phenylmethyl]-1- piperazinyl]ethoxy]acetic acid	461.8199
Epinastine hydrochloride	Alesion, Elestat, Purivist, Relestat	other	(RS)-3-amino-9,13b-dihydro-1H-dibenz(c,f)imidazo(1,5-a)azepine	285.779
Ketotifen fumarate	Zaditor	other	4-(1-Methylpiperidin-4-ylidene)-4,9-dihydro-10H-benzo[,5]cyclohepta[,2-b]thiophen-10-one	425.5075
Loratadine	Claritin, Claratyne	other	Ethyl 4-(8-chloro-5,6-dihydro-11H-benzo[,6]cyclohepta[,2-b]pyridin-11-ylidene)-1-piperidinecarboxylate	382.8938
Terfenadine	Seldane, Triludan, Teldane	other	(RS)-1-(4-tert-butylphenyl)-4-4-[hydroxy(diphenyl)methyl]piperidin-1-yl-butan-1-ol	471.6891
Third generation antihistamine
Fexofenadine hydrochloride	Allegra, Fexidine, Telfast, Fastofen, Tilfur, Vifas, Telfexo, Allerfexo, Flexofen	other	(±)-4-[-Hydroxy-4-[-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl]-α, α-dimethyl benzeneacetic acid	501.6719