| Objective Modify of pressure controllable microneedle roller and study its effect on drugabsorption of large area skin.Methods1.The commercially available microneedle roller was modified, the paraffinsection and HE staining method were used to evaluate the controllability of pressure of it.The in vitro permeation characteristics were studied by Franz diffusion cell. Score methodwas used to investigate the skin irritation. To optimize method of microneedle using such asthe frequency, intensity and density, Franz diffusion cell, Methylene blue staining andCLSM method were used. TEWL and laser doppler methods were used to investigate the skinirritant of microneedle in healthy body and hyperplastic scar patients.2.The in vivo absorption amount, skin and plasma accumulation of microneedles andinjection group were investigated by using the elution method and the homogenizationmethod respectively; The in vitro permeation characteristics were studied by Franz diffusioncell; homogenization after frozen section were used to investigate the dexamethasone sodiumphosphate uniformity of microneedle and injection. SEM, TEWL and laser doppler methodwere used to investigate the skin irritation.3.Effect of different concentrations of essential oils from Ligusticum chuanxiong Hortand phenylephrine on blood flow of nude mice skin were studied under the laser dopplermethod, Franz diffusion cell were used to contrast of its effect on nude mice in vitro skin, skinirritation and histological changes of nude mouse were determined by score method and lightmicroscopy respectively.Results1.Modified microneedle roller can improve the controllability of pressure,reproducibility of drug release and skin irritation was little. The pore depth was increased with increasing of the pressure, the range of pore depth was narrowed from65.28～106.25μm to71.53～97.92μm by the modified microneedle roller, the range of the RSD was significantlydecreased from10.45%～19.69%to2.33%～9.21%by the modified group. At the samepressure of the microneedle roller, the RSD range of the accumulative penetration amount oftriamcinolone acetonide was decreased markedly from34.75%～55.92%to14.29%～29.73%.The mild stimulus intensity was observed one hour after the administration by using themodified microneedle roller, and then all the irritation symptoms were disappeared.The result of the optimization experiments suggests better with540-needles,3.5~4.0Nin microneedles density and the pressure aspects. Tretinoin penetrate better when deliverytime was2h and had smaller skin irritation in human subjects. The cumulative penetrationamount of540-needles microneedle group tretinoin was6.8times of the control group, whichhad stronger penetration effect compared with2.5times of the192-needles microneedle group(P<0.05). The penetration depth of tretinoin after administered2h was30μm when pressurewas2.5~3.0N, while the penetration depth had no significant difference between3.5~4.0Ngroup and4.5~5.0N group, and the penetration depth were both40μm.According to the results of different insertion times groups, with the increase oftreatment times, the penetration got better, but after8times into balance, nude mousehad slight stimulation when treatment times were5times or under. The48h cumulativeamount and flux of10times was highest, which were significantly higher (P<0.05) than thecontrol of3.1-fold and4.1-fold, separately（P<0.05）.8times was followed of2.6-fold and3-fold.8times and10times were similar to each other, about3-fold higher than control group.The number of permeation spot grows and tends to uniform as increase of inserting times,however8times and10times were similar, unsignificantly difference. According to theresults of TEWL and blood flow, TEWL and blood flow increase rapidly after microneedletreatment and accentated with the increase of the insertion times; When handling10times,influence of TEWL and blood flow to the skin were the largest, and the recovery time were also the longest; the TEWL recovery time of1,3,5times treatment group were24h and48hfor8,10times. All groups except the8,10times, which values remained elevated for at least120min, the blood flow returned to baseline values within60min. The microneedle group toTEWL and blood flow affect of healthy people were fully recovered within90min, and scarpatients fully recover in45min.2.Compare with intradermal injection administration, microneedle administrationdisplayed more advantages, higher efficient and continuous penetration, higher drugdistibution in skin and higher distribution uniformity, while with little skin irritation.Intradermal injection group, in vitro penetration of nude mice was very fast, transdermalcumulative dose upto83.76%in4h after injection, and after4h penetration went slow. But themicroneedle group, in vitro penetration was slow at beginning, total transdermal cumulativedose was only25.75%in first4h after treated, while penetration rate was steady andcontinuously.12h skin dose retention of intradermal injection group was less and only was36.14%of microneedle group. In vivo skin dos retention of intradermal injection group in1hwas94.52%of microneedle group, skin dose retention of intradermal injection group wentdown gradually, and after12h, it was only18.96%of1h dose retention; while the skin doseretention of microneedle group increased with time,12h skin dose retention was6.92times ofintradermal injection group. Beside this,12h plasma dose concentration of microneedlegroup was3.16times of control group, and2.25times of intradermal injection group.Intradermal injection group the retention of drug aroud injection points was very high whileonly very little outside the injection points. Difference between peak and valley was upto286.21%, while the microneedle group’s skin dose retention was comparely more balanced,difference between peak and valley was only114.61%. TEWL measurements displayed thatthe skin surface water loss affect of microneedle group is larger than the injection group, butstimulation eliminated after24h; while laser Doppler blood flow method showed thatintradermal injection had a greater impact on skin blood flow. 3.Essential oils from Ligusticum chuanxiong Hort and phenylephrine had no affect on invitro skin penetration of microneedle, but can regulate microneedle administration bychanging the skin blood flow in vivo. Each treatment group in vitro experiments, cumulativepermeation within12h, permeation rate and drug retention volume of skin within12h haveno significant difference; In vivo, the dose amount in the administered skin of the10%essential oils Group were lowest,1.45±0.42μg, only was0.5times the control group(P<0.05), while in the group with0.15%phenylephrine injection site skin drug content is3.89±1.52μg,which is1.32times the control group (P<0.05); while the drug content in plasmawere at oppsite way,3%essential oils group and10%group were5.39times and6.39times the control group respectively (P<0.05), while0.15%phenylephrine group was only0.61times the control group (P<0.05); total absorption amount of10%essential oils groupwas highest and was2.05times of the control group. Total absorption amount of the groupwith0.15%phenylephrine was minimum; All groups showed mild stimulation in skinirritation experiment during1h performance. All experimental nude mouse were completelyrestored after48h. Skin tissue examination results showed that after6h of the microneedletreatment, there were only slight cuticles peeling and deletion. The irritation was not increasedafter adding essential oils and phenylephrine, and did not appear inflammatory cells and otherinflammatory reactions.Conclusions The modify pressure controllable microneedle roller, significantly improvedthe controllability of pressure, reproducibility of drug release and dosing uniformity. Byoptimizing the method of using modified microneedle roller, the administration operability ofa large area of hypertrophic scars and penetration effect of dexamethasone sodium phosphatewere enhanced. The modify pressure controllable microneedle roller abstained the pain andinconvenience of administration of Intradermal Injection, and have high transdermalpenetration and drug concentration in skin and uniformly distribut drugs in skin. Thedistribution of transdermal drug in the skin and blood can be affected by changing skin blood flow. Appropriate phenylephrine can effectively increase the dose of the lesion site and canreduce the drug into the blood by locally slowing the skin blood flow. |
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