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PolimeryRyc. 3. Zmiany pH w kompartmencie donorowym(po lewej), oraz w kompartmencie akceptorowym(po prawej) – szczegóły w tekścieFig. 3. The pH changes in the donor (left panel), andacceptor (right panel) compartment - details in thetextwały się opalescencją, co wskazuje na równomiernerozproszenie osadu w systemie wodnym – rycina 4.Fakt ten umożliwia zastosowanie tych systemówna skórze w formie maści, kremów lub żeli. Otrzymanakompozycja umożliwia przedłużone utrzymanieniskiego odczynu na powierzchni skóry. Według53ciation of polyacrylic acid. According to theequi libriums, the polyacrylic acid sedimented, howeverobtained mixture was opalescent rather, and homogenouslydispersed in aqueous environment – Figure4.This enables the application of the system onskin in the form of an ointment, cream, or gel. Thecomposition enables prolonged maintaining of lowpH on the skin. According to our data from formerrelease experiment, the pH was maintained on thelevel not higher then 4,0 in the period of 12 hours,whereas in the case of preparation with methylcellulose,the pH increased from acceptable pH of ca. 4,5to the level of above 6,0 [18]. The application of polyacrylicacid as the vehicle for the preparation appliedon the skin should give better clinical answer, comparingto the preparation with methylcellulose. Additionalfeature would be the prolongation of thedrug release due to the formation of microprecipitate.On the Figure 5, there are microphotographs of preparationsof lidocaine hydrochloride with polyacrylicacid (left ), and with methylcellulose (right).Also in the acceptor compartment the pH alteredwith time, when release of the drug occurred. The startingvalue of the acceptor compartment was assessed asca. 5,5 pH. With time, and increasing amount of lidocainein the compartment, the opposite tendencies wereobserved in the systems with methylcellulose and polyacrylicacid. In the acceptor compartment relative toPA-LD system the pH decreased, as expected, accordingto the increase of concentration of hydrochloride salt oflidocaine in the acceptor compartment.Considering the release of total amount of lidocainehydrochloride to the acceptor compartment,the concentration would be in the range of 0,015mol/l, what reflects the pH of ca. 5,0 for the salt oflidocaine and hydrochloric acid, and pH ca. 7,0 forMC-LD-22MC-LD-32MC-LD-41Ryc. 4. Obrazy próbek ogrzewanychw warunkach odpowiadającychwarunkom eksperymentu,tj. w temp. 22°C, 32°C i 41°C– w badanym zakresie stężeńnie zaobserwowano osaduPA-LD-22PA-LD-32PA-LD-41Fig. 4. Images of samples heatedin the conditions reflecting theexperiment, i. e. at 22°C, 32°Cand 41°C – in respective temperaturesno sedimentation wasobserved