Table 1.
Skin penetration enhancers studied (listed alphabetically according to chemical classes).
| Chemical | Log Koctanol/PBS or Log Koctanol/water | Class | References |
|---|---|---|---|
| Ethanol | −0.30 a | Alcohol | Kim et al. [6] |
| 1-Propanol | 0.25 a | Alcohol | Kim et al. [6] |
| 1-Butanol | 0.84 a | Alcohol | Kim et al. [6], Chantasart and Li [36] |
| 1-Pentanol | 1.5 a | Alcohol | Kim et al. [6], Chantasart and Li [36] |
| 1-Hexanol | 2.1 b | Alcohol | Warner et al. [24], Ibrahim and Li [40,56] |
| 1-Heptanol | 2.5 b | Alcohol | Warner et al. [24], Chantasart et al. [27] |
| 1-Octanol | 3.1 b | Alcohol | Warner et al. [24], Ibrahim and Li [40,56] |
| 1-Nonanol | 3.5 b | Alcohol | Chantasart et al. [27] |
| 1-Undecanol | 4.2 c | Alcohol | Ibrahim and Li [40,56] |
| Oleyl alcohol | 7.0 d | Alcohol | Ibrahim and Li [40,56] |
| 2-Hexanol | 1.83 b | Alcohol | Chantasart et al. [27] |
| 3-Hexanol | 1.81 b | Alcohol | Chantasart et al. [27] |
| 2-Heptanol | 2.43 b | Alcohol | Chantasart et al. [27] |
| 3-Heptanol | 2.42 b | Alcohol | Chantasart et al. [27] |
| 4-Heptanol | 2.32 b | Alcohol | Chantasart et al. [27] |
| 2-Octanol | 3.03 b | Alcohol | Chantasart et al. [27] |
| 3-Octanol | 2.94 b | Alcohol | Chantasart et al. [27] |
| 4-Octanol | 2.88 b | Alcohol | Chantasart et al. [27] |
| 2-Nonanol | 3.48 b | Alcohol | Chantasart et al. [27] |
| 3-Nonanol | 3.47 b | Alcohol | Chantasart et al. [27] |
| 4-Nonanol | 3.46 b | Alcohol | Chantasart et al. [27] |
| 5-Nonanol | 3.42 b | Alcohol | Chantasart et al. [27] |
| cis-3-Penten-1-ol | 1.08 e | Alcohol | He et al. [26] |
| cis-3-Hexen-1-ol | 1.63 e | Alcohol | He et al. [26] |
| cis-3-Octen-1-ol | 2.71 e | Alcohol | He et al. [26] |
| cis-3-Nonen-1-ol | 3.25 e | Alcohol | He et al. [26] |
| trans-3-Hexen-1-ol | 1.76 e | Alcohol | He et al. [26] |
| trans-Hydroxyproline-N-decanamide-C-ethylamide | 2.9 f | Amide/Alcohol | Warner et al. [24] |
| N,N-Dimethylhexanamide | 1.4 g | Amide | Warner et al. [23] |
| N,N-Dimethylheptanamide | 1.9 g | Amide | Warner et al. [23] |
| N,N-Dimethyloctanamide | 2.6 g | Amide | Warner et al. [23] |
| N,N-Dimethylnonanamide | 1.9 g | Amide | Warner et al. [23] |
| Benzyl alcohol | 1.1 d | Aromatic ring: alcohol | Ibrahim and Li [40,56] |
| 2-Phenoxyethanol | 1.2 h | Aromatic ring: alcohol | Ibrahim and Li [40,56] |
| 2-Phenylethanol | 1.6 i | Aromatic ring: alcohol | Chantasart et al. [30] |
| Padimate O (PadO) | 5.8 d | Aromatic ring: aminobenzoate | Ibrahim and Li [40,56] |
| Butylated hydroxyanisole | 3.1 j | Aromatic ring: hydroxyanisole | Ibrahim and Li [40,56] |
| 2-Ethylhexyl salicylate | 6.0 d | Aromatic ring: salicylate | Ibrahim and Li [40,56] |
| Salicylaldehyde | 2.0 d | Aromatic ring: salicylate | Ibrahim and Li [40,56] |
| 1-Butyl-2-azacycloheptanones | 1.8 f | Azone | He et al. [25] |
| 1-Hexyl-2-azacycloheptanones | 2.9 f | Azone | He et al. [25] |
| 1-Octyl-2-azacycloheptanones | 4.0 f | Azone | He et al. [25] |
| Laurocapram (Azone) | 6.3 k | Azone | Ibrahim and Li [40,56] |
| 1,2-Hexanediol | 0.78 f | Diol | Warner et al. [23] |
| 1,2-Octanediol | 2.1 f | Diol | Warner et al. [23] |
| 1-2-Decanediol | 3.2 f | Diol | Warner et al. [23] |
| 2-(1-Butyl)-2-methyl-1,3 dioxolane | 2.1 f | Dioxolane | Warner et al. [24] |
| 2-(1-Hexyl)-2-methyl-1,3 dioxolane | 3.5 f | Dioxolane | Warner et al. [24] |
| Isopropyl myristate | 7.3 d | Ester | Ibrahim and Li [40,56] |
| Decanoic acid | 4.0 d | Fatty acid | Ibrahim and Li [41] |
| Undecanoic acid | 4.5 d | Fatty acid | Ibrahim and Li [41] |
| Lauric acid | 5.0 d | Fatty acid | Ibrahim and Li [41] |
| Tridecanoic acid | 5.5 d | Fatty acid | Ibrahim and Li [41] |
| Myristic acid | 6.0 d | Fatty acid | Ibrahim and Li [41] |
| Pentadecanoic acid | 6.5 d | Fatty acid | Ibrahim and Li [41] |
| Palmitic acid | 7.0 d | Fatty acid | Ibrahim and Li [41] |
| Stearic acid | 7.9 d | Fatty acid | Ibrahim and Li [41] |
| Linoleic acid | 7.5 d | Fatty acid | Ibrahim and Li [41] |
| Oleic acid | 7.6 d | Fatty acid | Ibrahim and Li [40,41,56] |
| Ricinoleic acid | 6.2 d | Fatty acid | Ibrahim and Li [41] |
| 1-Octyl-β-D-glucopyranoside | 1.9 f | Glucoside | Warner et al. [24] |
| 1-Decyl-β-D-glucopyranoside | 3.1 f | Glucoside | Warner et al. [24] |
| 1,2-Dihydroxypropyl octanoate | 2.4 f | Monoglyceride | Warner et al. [24] |
| 1,2-Dihydroxypropyl decanoate | 3.1 f | Monoglyceride | Warner et al. [24] |
| 1-Butyl-2-piperidinone | 1.4 f | Piperidinone | Warner et al. [24] |
| 1-Hexyl-2-piperidinone | 2.6 f | Piperidinone | Warner et al. [24] |
| 1-Octyl-2-piperidinone | 3.4 f | Piperidinone | Warner et al. [24] |
| 1-Ethyl-2-pyrrolidone | −0.04 d | Pyrrolidone | Yoneto et al. [22,45] |
| 1-Butyl-2-pyrrolidones | 1.02 f | Pyrrolidone | Yoneto et al. [22,45] |
| 1-Hexyl-2-pyrrolidinone | 2.1 f | Pyrrolidone | Yoneto et al. [22] He et al. [25], Ibrahim and Li [40] |
| 1-Octyl-2-pyrrolidinone | 3.0 f | Pyrrolidone | Yoneto et al. [22] He et al. [25], Ibrahim and Li [40,56] |
| 1-Decyl-2-pyrrolidinone | 4.1 l | Pyrrolidone | Warner et al. [39] |
| 1-Dodecyl-2-pyrrolidinone | 4.9 l | Pyrrolidone | Warner et al. [39] |
| Thymol | 2.5 m | Terpene | Chantasart et al. [31] |
| Menthol | 3.4 m | Terpene | Chantasart et al. [31] |
| Menthone | 2.9 m | Terpene | Chantasart et al. [31] Ibrahim and Li [40] |
| Carvacrol | 2.5 m | Terpene | Chantasart et al. [31] |
| Cineole | 3.1 m | Terpene | Chantasart et al. [31] |
| 1,2,3-Nonanetriol | 1.6 f | Triol | Warner et al. [24] |
a Values from the literature [57]; b Experimental values from the literature [27]; c Experimental values from the literature [58]; d Calculated values based on the chemical structure of the compound, obtained from EPI suite database; e Experimental values from the literature [26]; f Experimental values from the literature [24]; g Experimental values from the literature [23]; h Experimental values from the literature [59]; i Experimental values from the literature [30]; j Experimental values from the literature [60]; k Experimental values from the literature [61]; l Experimental values from the literature [39]; m Experimental values from the literature [31].