Five fatty acids ( oleic, linoleic, myristic, lauric and capric ) were incorporated in 10 % ( w/w ) into ointment preparation and their influence on theoretical account drug tolnaftate release in vitro and heightening consequence on tolnaftate incursion into cuticle and corium of human tegument ex vivo were investigated. The prepared unctions were tested for homogeneousness, pH and rheological belongingss. In vitro release surveies and ex vivo skin incursion experiments were carried out utilizing Hanson and Bronaugh-type flow-through diffusion cells, severally. Tolnaftate cumulative sum liberated from semisolids was assayed utilizing UV-Vis spectrophotometer. After in vitro skin incursion surveies, suitably extracted human tegument beds were analysed for tolnaftate content utilizing a validated HPLC method. Statistical analysis revealed that release rate of tolnaftate from control unction and unctions with fatty acids was non significantly different and merely 7.34 – 8.98 % of drug was liberated into an acceptor medium after 6 hours. Tolnaftate sum perforating into 1 cm2 of cuticle from unctions holding oleic, linoleic, myristic and lauric acids was significantly greater ( P & lt ; 0.05 ) than from the control unction. Enhancing ratios of these fatty acids for tolnaftate incursion into cuticles ranged from 1.48 to 1.75. In decision, fatty acids did non increase the release of tolnaftate from ointment preparation, but exerted their enhancing consequence on tolnaftate incursion into human cuticle in vitro. Consequences from in vitro release experiments do non calculate the state of affairs on the tegument in vitro, if chemical incursion foils are incorporated into the preparation.
Tolnaftate Penetration Into Human Skin Layers From Ointment Biology Essay
Integral stratum horny layer ( SC ) , the outermost bed of the tegument, maps as the chief barrier for the incursion to and pervasion through the tegument for drug molecules. In the SC, corneocytes are surrounded by uninterrupted matrix of impersonal lipoids. Independently of the molecule inactive diffusion by the polar transcellular or lipoidal intercellular path, it has to spread through the lipid beds in order to traverse the barrier. Therefore, change of SC lipid organisation by perturbing the hydrophobic lipoid dress suits influences the rate and extent of SC opposition to the diffusion procedure. This reversible change might be achieved by adding variuos lipotropic chemical incursion foils ( CPEs ) , which are pharmaceutically acceptable, to the drug preparation.
The SC lipoids, which are arranged into lamellar bilayers ( 1 ) , are chiefly composed of ceramides ( 40-50 % ) , free fatty acids ( 10-15 % ) and cholesterin ( 25 % ) in an about 1: 0.9: 0.4 mol ratio ( 2-7 ) . Lipophilic CPEs interact with lipid hydrocarbon ironss, interrupt the order of lipid wadding and increase fluidization in the bilayers. In this manner CPEs are capable to locally heighten the incursion of active compounds into SC and through it ( 8 ) .
Fatty acids belong to the lipotropic CPEs and their incursion heightening belongingss are related to the hydrocarbon concatenation length and the presence of dual bonds. Obviously, the vehicle in which the CPE is dissolved besides influences the magnitude of sweetening ( 8 ) . Oleic acid is considered to be the most possible CPE among fatty acids due to its cis-monounsaturation and aˆzkink ” formation ( 2 ) . Oleic acid creates a extremely permeable, fluid-like stage within the SC lipoids ( 9 ) .
Tolnaftate was chosen as a exemplary drug for the probe of the heightening consequence of five fatty acids ( oleic, linoleic, myristic, lauric and capric ) on its incursion from 1 % ( w/w ) unction preparation into cuticle and corium of human tegument after in vitro skin incursion experiments. Tolnaftate is a topical fungicidal drug of thiocarbamate category, moving against dermatophytes, which chiefly invade the superficial beds of the tegument. Tolnaftate is a lipotropic compound ( XLogP = 5.5 ) of low molecular weight ( 307.4 Da ) , holding weak basic belongingss and runing point of 109 A°C-112 A°C ( Eur. Pharm.6.0 ; 01/2008:1158 ) .
MATERIALS AND METHODS
Chemicals and reagents
Tolnaftate ( O-naphthalen-2-yl methyl ( 3-methylphenyl ) thiocarbamate ; Eur. Pharm. 6.0 ) with pureness of 99.7 % was a gift from pharmaceutical company Sanitas AB ( Kaunas, Lithuania ) . Polyethylene glycol 400 ( PEG 400 ) was purchased from Carl Roth GmbH ( Karlsruhe, Germany ) . Polyethylene ethanediol 1500 ( PEG 1500 ) and capric acid ( decanoic acid, C10:0 ) were obtained from Merck Schuchardt OHG ( Hohenbrunn, Germany ) ; white Vaseline, anhydrous wool fat, oleic acid ( cis-9-octadecenoic acid, C18:1 ) and methanol ( ChromasolvA® ) were purchased from Sigma-Aldrich Chemie GmbH ( Steinheim, Germany ) . Ethanol ( 96.3 % ) was obtained from Stumbras AB ( Kaunas, Lithuania ) . Linoleic acid ( cis, cis-9,12-octadecadienoic acid, C18:2 ) , myristic acid ( tetradecanoic acid, C14:0 ) and lauric acid ( dodecanoic acid, C12:0 ) were purchased from Alfa Aesar GmbH ( Karlsruhe, Germany ) . Sodium azide ( NaN3 ) was obtained from POCh ( Gliwice, Poland ) . All other reagents were of analytical class.
Human skin readying
Caucasic adult females ( of age 25-40 ) abdominal tegument was obtained after decorative surgery in the Department of Reconstructive and Plastic Surgery, Hospital of Kaunas University of Medicine. The surveies with human tegument were approved by Kaunas Region Bioethical Committee. The suitably treated tegument was wrapped in aluminium foil and stored at -20 °C for non longer than 6 months before usage.
The prepared unctions were evaluated microscopically, utilizing MoticA® B3-series ( Meyer Instruments, Texas, USA ) with integrated Moticam 1000 digital microscope camera. pH values and rheological belongingss were assessed utilizing portable pH-meter HD2105.1 ( Delta OHM, Italy ) and rotary viscosimeter ST-2010 ( JP Selecta S.A. , Spain ) , severally.
In vitro release surveies were carried out utilizing an assembly constructed in our research lab. Hanson perpendicular diffusion cells, holding semisolid preparation deposited in the donor chamber and covered by CuprophaneA® cellulose-dialysis membrane ( Medicell International Ltd, London, United Kingdom ) , were inserted into the glass beaker and overlayered with an appropriate acceptor medium. The glass beaker was put into the thermostated H2O bath ( Grant GD120, Grant Instruments Ltd, Cambridge, Great Britain ) and efficient commixture of the acceptor medium was achieved utilizing Heidolph RZR 2021 mechanical scaremonger with propeller-type impeller ( Heidolph UK, Essex, United Kingdom ) .
The equipment for in vitro skin incursion experiments consisted of thermostated H2O bath ( Grant GD120, Grant Instruments Ltd, Cambridge, Great Britain ) , peristaltic pump ( MasterflexA® L/SA® pump thrust ( exemplary type 7524-45 ) with multichannel pump caput ( exemplary type 07535-08 ) , Cole-Parmer Instrument Co. , Illinois, USA ) and Bronaugh-type flow-through diffusion cells, made from Teflon. Extraction process of human tegument beds was performed in the Bandelin Sonorex Digitec Ultrasonic Bath ( DT 156, Bandelin electronic GmbH & A ; Co. KG, Berlin, Germany ) , holding supersonic extremum end product of 640 W.
UV spectrophotometrical analysis was done utilizing UV/Vis Unicam Helios-I± spectrophotometer ( Unicam, Analitical Technology INC, Cambridge, Great Britain ) .
High peformance liquid chromatography ( HPLC ) analysis was carried out utilizing Shimadzu Liquid Chromatograph ( Shimadzu Corporation, Kyoto, Japan ) equipped with two Shimadzu LC-10AD VP pumps, degasser DGU-14A, car injector SIL-10AD VP, system controller SCL-10A VP, UV-vis sensor SPD-10A and column oven CTO-10AC VP.
Preparation of unctions
1 % ( w/w ) tolnaftate unctions were prepared by fade outing tolnaftate in PEG 400 and integrating the solution into the soaking up base ( merger technique ) . The soaking up base was composed of white Vaseline, anhydrous wool fat and PEG 1500. These constituents were melted together ( 70 °C ) on a steam bath and the hot ( 70 °C ) solution of tolnaftate in PEG 400 was easy added. Stiring was maintained until congealed.
Ointments holding 10 % ( w/w ) of different fatty acids were prepared in the same mode as the control unction except that an appropriate sum of fatty acid was melted together with the constituents of the soaking up base ( myristic, lauric and capric acids ) or poured into the liquefied stage ( oleic and linoleic acids ) . The precise composing of the unctions prepared is presented in Table 1.
Physico-chemical belongingss of prepared unctions
Homogeneity, pH and rheological belongingss of prepared unctions were evaluated. For homogeneousness appraisal, the unctions were smeared on the glass slide and examined under the microscope. For pH rating, each unction ( 2.5 g ) was heated ( 50 °C ) in 50 milliliter of distilled H2O and stirred on the magnetic scaremonger for 50 min. Cooled solutions were filtered through ashless filter paper ( AlbetA® 145, pore diameter 7-11 Aµm ) and their pH was evaluated utilizing pH-meter. Dynamic viscousness I· ( PaA·s ) of each unction was assessed at ambient temperature ( 21 °C ) utilizing rotary viscosimeter coupled with cylindrical spindle ( R7 ) , revolving in the selected velocity interval of 1.5-10.0 revolutions per minute ( each measuring lasted for 50 sec, n=3 ) .
In vitro release surveies
In vitro release trials were carried out utilizing Hanson perpendicular diffusion cells with effectual diffusion country of 1.77 cm2. Accurately weight sum of unction ( about 0.8 g ) was spread equally in the giver compartment and covered with the CuprophanA® cellulose-dialysis membrane, which was pre-hydrated in distilled H2O at 37 °C for 24 hours. 100 milliliter of acceptor medium, composed of 50/50 PEG 400/96.3 % ethyl alcohol, provided sink conditions ( solubility of tolnaftate at impregnation was determined to be 18.75 A± 1.06 mg/ml, n=3 ) . The acceptor medium was assorted at 100 revolutions per minute, utilizing mechanical scaremonger with propeller-type impeller. The whole assembly was kept in the H2O bath ( 37 °C ) . Aliquots of 3 milliliters were collected after 1, 2, 4 and 6 hours. After backdown of an aliquot, an equal volume ( 3 milliliter ) of an acceptor medium ( 37 °C ) was instantly added to keep a changeless volume. The samples were analyzed utilizing UV spectrophotometer.
In vitro skin incursion experiments
Bronaugh-type flow-through diffusion cells, mounted with full-thickness human tegument ( the diffusional country being 0.64 cm2 ) and holding the receptor volume of 0.13 milliliters, were placed on the warming block ( 37 °C ) . 12 hours equilibration period was followed, go arounding physiological solution holding 0.005 % NaN3 underneath the tegument. After the equilibration period, about 200 milligram of the giver stage ( infinite dosage ) was applied on the SC side of the skin surface for 24 hours. The cells were covered with aluminium foil. The acceptor fluid, which was pumped at a rate of 0.6 ml/min by the peristaltic pump, was composed of 4 milliliter of 0.9 % NaCl + 0.005 % NaN3 and it was wholly replaced after 4, 8 and 24 hours. After 24 hours the donor stage was removed and the skin surface was rinsed 2 times with 0.5 milliliters of 96.3 % ethyl alcohol and so 2 times with 1 milliliters of physiological solution. The outer remainders of tegument samples were trimmed away, go forthing the cardinal circles with country of 0.64 cm2.
Separation of tegument beds and their extraction
Epidermis was separated from the remainder of the tegument ( corium ) utilizing dry heat separation method. The skin sample was placed ( on the epidermis side ) on the hot surface ( 60 °C ) for 1-2 seconds and cuticle was peeled off. Then cuticle and corium were individually extracted with 1 milliliters of pure methyl alcohol, following bath sonication for 30 min. The supernatant was filtered through nylon membrane filter ( 0.45 Aµm, Carl Roth GmbH, Karlsruhe, Germany ) and injected into HPLC.
UV/Vis spectrophotometrical method
Samples obtained after in vitro release surveies were analyzed utilizing UV/Vis spectrophotometer. The optical density extremums of tolnaftate were measured at I» = 257 nanometer and the standardization curve ( in the concentration scope of 1.5-7.5 Aµg/ml ) was prepared in the acceptor medium, composed of 50/50 PEG 400/96.3 % ethyl alcohol ( R2 = 0.9984, y = 59.77x + 0.4247 ) . UV spectrophotometrical method was besides used to quantify tolnaftate content staying in the giver stage and skin lavations, after in vitro skin incursion experiments. The donor stage, staying on the tegument surface, was carefully removed, suitably extracted ( utilizing 96.3 % ethyl alcohol and sonication at 60 °C for 30 min ) , filtered through the nylon membrane filter ( 0.45 Aµm ) and analyzed harmonizing to the standardization curve ( in the concentration scope of 3.0-15.0 Aµg/ml ) prepared in 96.3 % ethyl alcohol ( R2 = 0.9948, y = 58.47x + 0.09089 )
A validated HPLC method with UV sensing ( 10 ) was used to find tolnaftate sum, perforating into cuticle and corium from 1 % tolnaftate unctions after 24 hours of topical application. The samples of receptor fluid were besides analysed utilizing HPLC.
Separation of tolnaftate from endogenous compounds, deducing from skin matrix, was accomplished on a LiChrospherA®100 RP-18 Endcapped column, 125 ten 4 millimeter, ID, packed with 5 Aµm size atoms ( Merck KGaA, Darmstadt, Germany ) . A LiChrospher 100 RP-18e ( 5 Aµm ) ( LiChroCART 4-4 ) was used as a guard column.
Isocratic elution, utilizing 70 % methyl alcohol and 30 % bi-distilled H2O as the nomadic stage, resulted in tolnaftate keeping clip of 13.2 min and the overall running clip of 15.0 min. The flow rate of the nomadic stage was set to 0.8 ml/min and the injection volume was 10 Aµl. The column was thermostated at 40 °C and tolnaftate sensing was set at I» = 257 nanometer.
For the statistical analysis, one-way analysis of discrepancy ( ANOVA ) together with Tukey ‘s HSD trial were applied utilizing SPSS package version 12.0. The degree of significance was determined as P & lt ; 0.05.
Quality control trials of prepared unctions
The prepared unctions were all unvarying in visual aspect, holding light xanthous coloring material and an smell of oil ( in instance of oleic or linoleic acid ) or a specific smell of concentrated fatty acid added. Observation of prepared unctions under the microscope revealed, that no crystals were present and the form of solidifying ( chiefly caused by PEG 1500 ) was seen.
pH values of 1 % ( w/w ) tolnaftate control unction and unctions with fatty acids are presented in Table 2. Ointments with 10 % of fatty acids had lower pH values comparing to the control, but the pH was apropriate for application of these unctions on the skin surface ( pH of SC and upper feasible cuticle is considered to be 4.0-4.5 and 5.0-7.0, severally ( 11 ) ) .
The rheograms, demoing the relationship between dynamic viscousness and selected velocity interval of cylindrical spindle rotary motion, are presented in Figure 1. The investigated unctions exhibited non-Newtonian pseudoplastic ( shear-thinning ) flow.
In vitro release profiles of tolnaftate from prepared unctions
The per centum of the cumulative sum of tolnaftate released from each unction after 1, 2, 4 and 6 hours is presented in Figure 2. The cumulative sum ( Aµg ) of tolnaftate released per unit membrane country ( 1 cm2 ) was plotted against square root of clip ( Higuchi-plot ; Figure 3 ) . Higuchi-plots yielded consecutive lines, the inclines of which were taken as release rates. Table 3 summarizes the parametric quantities of tolnaftate release from prepared unctions in vitro, consisting the cumulative sums ( in % ) of drug released after 6 H, release rates and coefficients of finding ( R2 ) . The one-dimensionality ( expressed as R2 in Table 3 ) of Higuchi-plots indicates, that diffusion of tolnaftate from unctions is a rate confining measure for drug release. Furthermore, it shows, that CuprophanA® membranes used were non restricting drug diffusion from the giver to receptor compartment. The slowdown clip for drug release, matching to x intercepts of the Higuchi-plots, were non transcending 15 min for all unctions tested.
Analysis of discrepancy ( ANOVA ) showed that release rate of tolnaftate from unctions was non significantly different ( P a‰? 0.05 ) .
Enhancing consequence of fatty acids on tolnaftate incursion into human tegument beds
Figure 4 and 5 present the sums ( Aµg/cm2 ) of tolnaftate penetrating into cuticle and corium, severally, from the control unction ( n=3 ) and from unctions holding 10 % ( w/w ) of different fatty acids ( n=3 ) after in vitro skin incursion experiments. The heightening consequence of five different fatty acids on tolnaftate incursion into 1cm2 of cuticle ( E ) or corium ( D ) was calculated as the heightening ratio ( ER ) utilizing the undermentioned expression:
The obtained ER values are presented in Table 4.
Statistical analysis revealed that tolnaftate sum perforating into cm2 of cuticle from the unctions holding 10 % of oleic, linoleic, myristic and lauric acids was significantly greater ( P & lt ; 0.05 ) than from the control unction. Capric acid did non significantly heighten tolnaftate incursion into epidermis comparing to the control. Harmonizing to Tukey HSD trial, three homogeneous subsets of groups whose agencies do non differ from one another, were found: unctions with ( I ) oleic, linoleic and lauric acid, ( two ) linoleic, myristic and lauric acid, ( three ) capric acid and control.
As tolnaftate is a hydrophobic substance, its high sums in hydrophilic coriums are unexpectable. Tolnaftate incursion into corium was non significantly enhanced from either ointment holding 10 % of fatty acid comparing to the control ( P a‰? 0.05 ) . These findings prove that fatty acids exert their enhancing consequence merely in the superficial beds of tegument.
Mass balance of tolnaftate after in vitro skin incursion surveies
In order to look into the experimental conditions used for in vitro skin incursion experiments, mass balance of tolnaftate was calculated. After in vitro skin incursion experiments the donor stage, staying on the tegument surface, was carefully removed, suitably extracted with 96.3 % of ethyl alcohol and analyzed by UV spectrophotometer. The tolnaftate sums staying in the giver stage and found in the cuticle and corium infusions were sumed up ( no drug was detected in the acceptor fluid ) and compared to the nominal sum of tolnaftate added on each tegument sample. The comparative mistake ( RE ) was calculated harmonizing to the expression:
The REs were calculated for each tegument sample and was in the scope from -4.19 % to 8.45 % . This is an indicant of apropriately chosen experimental conditions.
For the preparation of unction, white Vaseline was chosen as the chief vehicle for exemplary drug tolnaftate. Other ingredients were added to better preparation ‘s consistence, spreadability, visual aspect and tolnaftate solubility. PEG 400 was chosen as an appropriate dissolver for tolnaftate ( AHFS Drug Information, 1999 ) . 1 % tolnaftate solution and picks, available nonprescription, are besides normally formulated in PEG 400 or PEG 400 – propene ethanediol vehicle, severally. Nail down 1500 was added as a plasticizing and inspissating agent. Anhydrous wool fat acted as emulsifier. Fatty acids were chosen as powerful CPEs for a hydrophobic tolnaftate and they besides exhibited emulsifying belongingss. It is deserving adverting that polythene ethanediols are besides considered to be good CPEs ( 12 ) , therefore interactive heightening action of PEGs and fatty acids could be observed. Microscopic images of tolnaftate control unction showed clear boundaries of PEG 400 droplets, as anhydrous wool fat entirely was non able to expeditiously emulsify solution of tolnaftate in PEG 400. Addition of 10 % ( w/w ) fatso acids resulted in better emulsification: no clear boundaries of PEG 400 droplets, but hardening form of PEG 1500 could be observed in the microscopic images. Model drug tolnaftate was wholly soluble in the prepared unctions.
The pH values of prepared unctions were compatible with the tegument ‘s surface pH. Dynamic viscosity measuring of prepared unctions revealed that semisolid preprations exhibited non-Newtonian shear-thinning flow. Addition of solid fatty acids ( capric, lauric, myristic ) evidently resulted in higher dynamic viscousness scope comparing to the unctions with oleic or linoleic acid. Control unction was formulated with higher sum of white Vaseline ( alternatively of 10 % fatty acid ) , and merely preparation with 10 % myristic acid had higher dynamic viscousness scope comparing to the control.
Drug release from a semisolid dose signifier allows for drug handiness on the skin surface and is evaluated utilizing in vitro release trials. These trials characterize the public presentation of the vehicle in drug solubility, diffusion and release procedures. Three of import considerations have to be made before transporting out this type of experiments: ( I ) the chosen acceptor medium should supply “ sink conditions ” ( the sum of substance in acceptor medium after experiment should non transcend 30 % of it ‘s saturation concentration ) , ( two ) the diffusion membrane should non restrict drug diffusion from giver to receptor stage and act as an inert physical support, ( three ) the dosage of semisolid applied should be infinite. The chosen acceptor medium ( 50/50 PEG 400/96.3 % ethyl alcohol ) provided sink conditions and the cellulose membrane with nominal molecular weight cut-off of 10 kDa was non restricting drug diffusion. Furthermore, CuprophanA® membranes are recommended by USP 30 for transdermic bringing system release surveies. About 0.8 g ( 0.45 g / cm2 ) of merchandise were applied to the donor chamber and this corresponds to the space dose conditions ( 13 ) .
The release of drug from semisolid preparation chiefly depends on ( I ) the solubility of drug in the preparation and ( two ) the viscousness of semisolid. Tolnaftate was soluble in the unctions prepared by merger technique: microscopic observation of unctions prepared showed no crystals present. Increase in the viscousness normally consequences in the lower release of drug from semisolid. Harmonizing to the consequences obtained, add-on of liquid fatty acids ( oleic and linoleic acid ) to the unctions, resulted in higher release of tolnaftate, and this might be due to diminish of viscousness of the preparation and perchance due to solubilizing consequence of these fatty acids on hydrophobic tolnaftate.
ANOVA every bit good as Kruskal-Wallis trial showed that there is no important difference among the unctions tested on the release of tolnaftate ( P a‰? 0.05 ) . It means that CPEs do non hold a important consequence on the release of tolnaftate from ointment preparations and their enhancing consequence is merely ascertained after doing in vitro skin incursion experiments. Similar observations were made by Wagner et Al. ( 14 ) after probe of CPEs consequence on the release and incursion of flufenamic acid. The interpolation and interaction of fatty acerb molecules with the lipid spheres in SC, the addition of fluidization and break of lipid construction in the superficial beds of tegument, consequences in significantly higher incursion of tolnaftate molecules to epidermis from ointment preparations holding 10 % of oleic, linoleic, lauric and myristic acid comparing to the control.
Fatty acids increase the incursion of active drugs into the tegument through the non-polar path, which is really of import for the incursion of hydrophobic drugs, such as tolnaftate. The preparation of ointment itself, being the lipotropic base, has occlusive belongingss on the tegument. Therefore skin hydration might be increased besides ensuing in higher incursion of active molecules.
The dependance of fatty acerb hydrocarbon concatenation length and presence of dual bonds on its tegument incursion heightening belongingss is observed with our theoretical account drug tolnaftate. Among fatty acids tested, capric acid has the shortest concatenation length of C10 and this fatty acid did non significantly heighten the incursion of tolnaftate to epidermis comparing to the control. As stated by Kravchenko et Al. ( 15 ) , fatty acids holding hydrocarbon concatenation length of less than C11, produce deficient break of lipid alkyl groups. Oleic and linoleic acids are unsaturated and have the longest concatenation length of C18. These two fatsos acids were the strongest CPEs among others tested, but oleic acid was the most possible CPE due to its cis-unsaturation and ‘kink ‘ formation ( 2 ) , which is responsible for the fluidization of SC lipoids ( 9, 16 ) . Lauric acid ( C12 ) together with oleic and linoleic acids belonged to the same homogeneous subset ( Tukey HSD trial ) and had the really strong consequence on heightening tolnaftate incursion into cuticle. Similar consequences were obtained by Nair et Al. ( 17 ) after proving oleic, linoleic and lauric acids heightening consequence on Arginine Vasopressin. Lauric acid may hold a spacial signifier that is conformationally similar to the model of cholesterin ( 15 ) . Thus Nair et Al. ( 17 ) hypothesized that in the presence of lauric acerb break of ceramide-cholesterol or cholesterol-cholesterol interaction might happen. Myristic acid, which has the concatenation length of C14, besides significantly enhanced tolnaftate incursion into cuticle.
The unctions tested release tolnaftate in about the same mode ( about 8 % of tolnaftate was released after 6 hours from all preparations ) . The consequence of the semisolid vehicle on the soaking up dynamicss of tolnaftate into the tegument might be associated merely with the hydration procedure of skin surface ( 8 ) . However, fatty acids, presented in the unctions, penetrated into the tegument and interacted with the intercellular lipoids of the SC, upseting their construction and heightening the diffusion procedure of hydrophobic tolnaftate into human cuticle. Therefore in vitro release experiments are non foretelling the state of affairs on the skin surface ( 14 ) .
The formulated topical unctions, holding 10 % ( w/w ) of fatty acids, were intended to increase the bioavailability of tolnaftate in human tegument beds in vitro. Addition of fatty acids to the unctions, holding 1 % ( w/w ) of tolnaftate as a theoretical account drug, does non significantly better the release of active drug to the chosen acceptor medium comparing to the control, but significantly enhances drug incursion into human cuticle. This observation indicates that fatty acids exert their consequence merely when they are applied on the tegument, and accordingly no givens could be made about the heightening effects of CPE ‘s on drug incursion into the tegument after in vitro release experiments.