SOLID INTERACTION BETWEEN ACTIVE INGREDIENT COMBINATIONS AND THE INFLUENCE OF AMOXICILLIN TRIHYDRATE-POTASSIUM CLAVULANATE INTERACTION ON ITS STABILITY AND PHARMACOKINETIC PROFILE

• Main Author: Nugrahani, Ilma
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/45684
• Institution: Institut Teknologi Bandung

In pharmaceutical solid dosage forms, interaction between the active ingredient with excipients as well as between the active ingredients themselves can be promoted by thermal and mechanical energy involved during manufacturing process and changes of storage conditions. These interactions will influence physicochemical properties and stabilities of the drug. A comprehensive investigation of these interactions is very important to be performed in order to produce a drug formulation that fulfils legal and commercial requirements. Kofler’s Hot Stage Contact Method has been known as a simple and accurate method to observe type of physical interaction between two powders. However, this method cannot be applied for investigating interactions of thermolabile substances. In the first step of this research, the Cold Contact Methods (CCM) was developed that was based on re-crystallization behaviour from saturated solution. This method was proposed for wide application in the study of interactions of both thermolabile and thermostabile drug combinations. The CCM had been performed to various combinations of drug solution, including: acetaminophen – pseudoephedrine HCl (AP) in ethanol, metampyrone– phenylbutazon (MPh) in acetone, levodopa–benserazide HCl (LB) in formic acid, and amoxicillin trihydrate – potassium clavulanate (ATH-PC) in NaOH at pH 13 and phosphate buffer pH 6.8. From Differential Scanning Calorimetry (DSC) and Powder X-Ray Diffractometer (PXRD) analyses, it was confirmed that AP was a eutectic mixture with the eutectic point at 113°C, MPh and LB were peritecticum combinations with the peritecticum point at 149°C and 163.7°C, respectively. The isolate interactions of each binary system that were solubilized in the solvent used in CCM showed their appropriate characteristics. Due to the different phenomenon interaction of ATH-PC from those three other combinations where the contact point of ATH-PC was burnt at 200-205ºC and type of its physical interaction could not be established yet, therefore CCM analysis was performed further by isolating interaction of ATH-PC in phosphate buffer solution pH 6.8 using freeze drying method. Thermogram of ATH-PC physical mixture showed overlapping of their exothermic curve at 0.5 to 0.1 molar ratios of ATH, while the freeze-dried isolate from their solution in phosphate buffer at pH 6.8 at all ratios yielded the same melting point at 194 – 201.8°C. From this phenomenon, it can be hypothesized that amoxicillin – clavulanate combination underwent chemical reaction. FTIR analysis showed the disappearance of amine and carboxilate spectras and the overlapping the amine spectras at 1650 – 1700 cm -1 . NMR 500 MHz analysis showed a new H peak at 3.74 ppm bounded to C-58 ppm. These data opproved the hypothesis that chemical interaction occured between amoxicillin and clavulanate following freeze drying of the solution in phosphate buffer pH 6.8. Based on the overlapping of exothermic curves of ATH-PC physical mixture at the same ratio, it was predicted that hydrolysis of both substances occurred at similar temperatures. In the next step, the ATH – PC interaction at solid state without the existence of buffer was investigated thoroughly using solid state characterization instruments. Firstly, each single component of ATH and PC powders was analyzed by Single Crystal Diffractometry (SCD) and PXRD/DSC. On the single crystal structure study, it was depicted that ATH and PC have orthorombic P212121 crystal lattice with 4 (four) molecules in a crystal with 1950 ? 3 and 930 ? 3 volume of cells, respectively. ATH is a channel hydrate, which is type of hydrate that can release water crystal molecule easily from the lattice. While PC has 4 potassium atoms in each cell that make it polar and hygroscopic. Due to the high polarity and planar form, PC crystal can interact with water crystal molecules of ATH under condition. The three dimensional structure of these compounds showed that the lactam ring arranged a geometrical rectangle with the penta-cyclic moiety which make the unbound electrons can not resonance therefore easy to hydrolyze. Simultaneous DSC and PXRD data depicted that ATH released its hydrate at 100°C and became anhydrous followed by degradation at 160°C. Thermogram of PC showed exothermic transition at 180°C. The mixture of ATH-PC at the same molar ratio showed exothermic curve at 100°C subsequently after anhydratation process of ATH then showed the new exothermic curve at 145°C that was predicted as the temperature of intermolecular formation. After that, the mixture was decomposed at 180-220°C. The next step was study of the influence of various treatments on interaction of ATH-PC. The ATH-PC mixture were treated at various conditions, including: heating at 50°C for 30 minutes, grinding using mechanical mortar at 100 rpm rotation for 20 minutes, and grinding with ethanol. DSC’s thermogram showed that grinding and heating increased hydrate mobility of ATH, while grinding with ethanol tent to integrate ethanol within crystal lattice of ATH and PC. Diffractograms showed the decreasing of crystallinity after all the treatments. SEM photographs showed that ATH- PC surface structure became irregular and more porous. FTIR and NMR analyses showed that no new bound was formed after all of the treatments, although the broadening of the curve at 2500-3500 cm - 1 occured. This indicated the involvement of water in the ATH-PC interaction following heating and grinding without the change of their stuctures. Amorphous state of a subtance could increase its hydration and decrease its stability. The stability study at 26±2°C with relatif humidity of 65±5% and 84±2% showed that degradation of ATH in the mixture occured at higher rate with the degradation rate were in the order of ACFD>ACH>ACG>ACGE>ACPM>ATH, respectively. The relatif humidity was significantly influenced the stability of the mixtures and the degradation product of PC suspected to provoke the ATH degradation. In the last step, the pharmacokinetic analysis using bioassay method in rabbits was conducted to elaborate the influence of in vitro interaction on the value of bioavailability parameters. The results showed that ACPM (ATH-PC Physical Mixture) had higher tmax (hour), lower Cmax(µg/mL), and no significant different of AUC0-?(µg.hour/mL) compared to those of ATH. The tmax of ACGE was not significantly different compared to that of AGE (ATH ground with ethanol), although it’s Cmax and AUC0-?were significantly higher. While all parameters of AFD (ATH freeze-dried) were not different significantly compared to those of ACFD (ATH-PC freeze-dried). Therefore, the improvement of bioavailability from the single system was found in ACGE mixture only, compare to AGE. Compared to those of ACPM, both ACFD and ACGE had shorter tmax, which were 0.99 ± 0.16, 0.29 ± 0.11 and 0.56 ± 0.12, respectively; higher Cmaks, which were12.4 ± 2.80, 20.95 ± 2.32 and 17.55 ± 4.7, respectively, and higher AUC0-? which were 41.6 ± 6.42, 67.70 ± 8.3 and 57.8 ± 6.0, respectively. The increasing of bioavailibility of ACGE is predicted based on the improvement of ATH solubility after amorphus formation and the higher contact intensity between ATH – KK, compare to it’s physical mixture. The reasons of highest bioavailibility of ACFD are salt and amorphus formation, as well as increasing of porosity and higroscopicity after freeze-drying. It can be concluded that the difference of interaction system results in the difference of bioavailability, which is caused by the difference of solubility, dissolution rate, lipophilicity, and stability of ATH in the mixture. These data indicated that the freeze dried mixture had the highest bioavailability, followed by ACGE and ACPM.