STABILITY OF CEFTRIAXONE DISODIUM IN BIOTRAKSON AND TARTRIAKSON

Transcription

1 Acta Poloniae Pharmaceutica ñ Drug Research, Vol. 62 No. 2 pp. 89ñ94, 2005 ISSN Polish Pharmaceutical Society STABILITY OF CEFTRIAXONE DISODIUM IN BIOTRAKSON AND TARTRIAKSON MARIANNA ZAJ C, ANNA JELI SKA and PRZEMYS AW ZALEWSKI Department of Pharmaceutical Chemistry, Faculty of Pharmacy, PoznaÒ University of Medical Sciences, 6 Grunwaldzka Str., PoznaÒ, Poland Abstract: The influence of temperature and relative air humidity on the stability of ceftriaxone disodium (CTN) in Biotrakson and Tartriakson was investigated. At RH = 0%, the degradation of ceftriaxone was the first-order reaction, while at RH from 50.9% to 76.4% it was an autocatalytic first-order reaction relative to the substrate concentration. The influence of temperature on the stability of CTN was described by the following equations in the case of Biotrakson: RH = 0% ln k = (ñ23488±7320) 1/T ; RH = 76.4% ln k = (ñ9492±1128) 1/T , and for Tartriakson: RH = 0% ln k = (ñ23491 ± 7370) 1/T ; RH = 76.4% ln k = (ñ10397±3034) 1/T The influence of humidity on the stability of Biotrakson was described by the following equation: ln k = (0.0823±0.0272) RH% ñ17.0 and for Tartriakson ln k = ( ± ) RH% ñ Keywords: ceftriaxone disodium; HPLC method; stability; solid state Ceftriaxone disodium is a third-generation semisynthetic cephalosporin antibiotic with a wide spectrum of antimicrobial activity. It exhibits antimicrobial activity against the majority of most Gram-negative and Gram-positive bacteria including most strains of bacteria synthesizing β-lactamases (1). The stability and mechanism of ceftriaxone degradation in aqueous solution was investigated in previous studies (2ñ7). The aim of this paper was to study the kinetic of the reaction of degradation of CTN in Biotrakson and Tartriakson and to calculate the kinetic and thermodynamic parameters of the reaction at RH = 0% and RH = 76.4% and to evaluate the influence of humidity on the rate and mechanism of the reaction. EXPERIMENTAL Materials and chemicals Biotrakson ñ a powder containing ceftriaxone disodium, for preparing injections (Bioton Sp. z o.o.), Tartriakson ñ a dry substance containing ceftriaxone disodium for preparing injections and infusions (Polfa Tarchomin S.A.). All the chemicals used were of analytical reagent grade. Chromatographic conditions To evaluate the stability of CTN in Biotrakson and Tartriakson the forced degradation test was used. To estimate the changes of CTN concentration during the reaction, the HPLC method was used. This method was applied in earlier studies of the kinetic reaction of CTN degradation in aqueous solution (7). The method was validated to assess its suitability for analyzing the stability of CTN in Biotrakson and Tartriakson. The HPLC method Decomposition was followed by the HPLC method. The liquid chromatograph was equipped with a variable UV detector set at 235 nm, a Merck (Darmstadt, Germany) analytical column mm LiChrosorb RP-18 (5 µm), a Rheodyne 50 µl syringe loading injector. The mobile phase was water ñ 0.5 mole/l phosphate buffer ph = 7.6 ñ methanol (82:10:8). The flow rate was 1.0 ml/min; internal standard ñ nicotinamide (1.0 mg/ml). The validation of the HPLC method Linearity. Aqueous solutions of Biotrakson and Tartriakson at concentrations from mg/ml to mg/ml (n = 14) were prepared. To 1.0 ml of each sample 0.5 ml of aqueous solution (1 mg/ml) of internal standard ñ nicotinamide (I.S.) was added. 50 µl samples of the solutions were injected onto the column. During the calculations the quotient of peak area CTN/I.S. as a function of CTN concentration [mg/ml] was used. Biotrakson CTN/I.S. = (3.532 ± 0.139) c [mg/ml] (n = 14; Sa = ; Sy = ; 89

2 90 MARIANNA ZAJ C et al. Table 1. The first-order rate constants and thermodynamic parameters of the reaction of ceftriaxone disodium degradation in Biotrakson and Tartriakson preparations at various temperatures (RH = 0%) Tartriakson Biotrakson T[K] 10 6 k± k [s ñ1 ] Parameters of regression 10 6 k± k [s ñ1 ] Parameters of regression ln k i = f (1/T) ln k i = f (1/T) ± a± a=ñ23488 ± ± a± a=ñ23491 ± ± S a = ± S a = 2295 b ± b = ± b±db = 45.1 ± ± S ± y = S y = ± n = ± r = ñ ± r = ñ ± Thermodynamic parameters E a = ± 60.9 [kj mole ñ1 ] E a = 195 ± 61 [kj mole eñ1 ] H = ± 63.3 [kj mole ñ1 ] a) H = 193 ± 63 [kj mole ñ1 ] a) S = ñ129.8 ± 85.9 [J K ñ1 mol eñ1 ] a) S = ñ130 ± 86 [J K ñ1 mole ñ1 ] a) n, number of experiments; k = S a t αf ; E a activation energy; H, enthalpy; S, entropy; E a = ñar [J mole ñ1 ]; H = E a ñ RT [J mole ñ1 ]; S = R (ln A ñ ln (k B T)/h)) [J K ñ1 mole ñ1 ], where: k B denotes Boltzmann constant ( ñ23 [J K ñ1 ]); h, Planck constant ( ñ24 [J s]); R, universal gas constant (8.314 [J K ñ1 mol ñ1 ]); T, temperature [K]; a vectorial coefficient of Arrhenius relationship, and A represents frequency coefficient. a) Calculated for 298 K. The values t 0.5 and t 0.1 for the autocatalytic reaction were calculated from the formula t 0.1 = (bñ2.197)/k; t 0.5 = b/k. In the case of the first-order reaction, the values may be calculated from the formula t 0.1 = /k; t 0.5 = 0.693/k. Table 2. The autocatalytic first-order rate constant and thermodynamic parameters of the reaction of ceftriaxone disodium degradation in Biotrakson and Tartriakson preparations at various temperatures (RH = 76.4%) T,K Tartriakson Biotrakson 10 6 k± k, s ñ1 t 0,5 ± t 0,5, h t 0,1 ± t 0,1, h 10 6 k± k, s ñ1 t 0,5 ± t 0,5, h t 0,1 ± t 0,1, h ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.60 Parameters of regression ln k i = f(1/t) a ± a ñ10398 ± 3034 ñ9492 ± 1128 S a b ± b ± ± 3.19 S y n 6 6 r ñ ñ Thermodynamic parameters E a 86.4 ± 25.2 [kj mole ñ1 ] 78.9 ± 9.4 [kj mole ñ1 ]; H a) 84.0 ± 27.7 [kj mole ñ1 ] 76.4 ± 11.8 [kj mole ñ1 ]; S a) 89.0 ± [J K ñ1 mole ñ1 ] ± [J K ñ1 mole ñ1 ] The descriptions of symbols under Table 1.

3 Stability of ceftriaxone disodium in biotrakson and tartriakson. 91 Table 3. The effect of humidity on the stability of ceftriaxone disodium degradation in Biotrakson and Tartriakson preparations at 358 K Tartriakson Biotrakson RH 10 6 k± k [s ñ1 ] Dependence 10 6 k± k [s ñ1 ] Dependence [%] ln k i = f (RH) ln k i = f (RH) ± 0.17 a± a = ± ± 0.51 S a = ± 2.50 b± b = ñ15.49 ± ± ± 5.8 S y = r = ; n = ± ± ± 8.0 a± a = ± S a = b± b = ñ16.99 ± 1.97 S y = r = ; n = 4 The descriptions of symbols under Table 1. Figure 1. Semilogarithmic plots c t = f (t) for the decomposition of ceftriaxone disodium in Biotrakson (B) and Tartriakson (T) at RH = 0% at different temperatures. r = ; LOD = 2.28 µg; LOQ = 6.90 µg). Tartriakson CTN/I.S. = (3.564 ± c [mg/ml] (n = 14; Sa = ; Sy = ; r = ; LOD = 2.32 µg; LOQ = 7.03 µg). Precision Aqueous solutions of Biotrakson and Tartriakson at concentrations of 0.4 mg/ml were prepared. Ten independent measurements of the solutions were taken. The following results were obtained: for Biotrakson mean value CTN/I.S. = , standard deviation = , variation coefficient = 0.80%; for Tartriakson mean value CTN/I.S. = , standard deviation = , variation coefficient = 0.82%.

4 92 MARIANNA ZAJ C et al. Figure 2. Semilogarithmic plots c t = f(t) for the decomposition of ceftriaxone disodium in Biotrakson (B) and Tartriakson (T) at RH = 76.4% at different temperatures. Figure 3. Semilogarithmic plots c t /(c 0 ñ c t ) = f (t) for the decomposition of ceftriaxone disodium in Biotrakson (B) and Tartriakson (T) at different RH at 358 K.

5 Stability of ceftriaxone disodium in biotrakson and tartriakson. 93 Selectivity The method was selective for CTN (both for Biotrakson and Tartriakson) (retention time ñ t R = 3.90 min), I.S. (t R = 8.36 min) and product of degradation (t R = 2.01 min). Conditions of the kinetic studies For the experiments, 10 mg samples of CTN were weighed into 5 ml open vials. To assess the effect of humidity on the stability of CTN, the vials with CTN were placed in desiccators containing aqueous saturated solutions of the following inorganic salts: sodium bromide (RH ~ 50.9%); sodium nitrate (RH ~ 66.5%); sodium chloride (RH ~ 76.4%) and zinc sulphate (RH ~ 90.0%) and inserted in a heat chamber set to 358 K. Samples destined for investigation of the effect of temperature at a relative humidity of 76.4% were placed in desiccators containing aqueous saturated solutions of sodium chloride and inserted in heat chambers set to the following temperatures 333 K, 343 K, 353 K, 358 K, 363 K, 373 K. To assess the stability of CTN in dry air, the vials with the studied substance were immersed in a sand bath, in a heat chamber adjusted to 373 K, 378 K, 383 K, 388 K, 393 K. At appropriate time intervals, determined by the rate of degradation, the vials were removed from the chamber, cooled to room temperature, the contents dissolved in water and refilled to a total volume of 25.0 ml in a volumetric flask. After filtration to 1.0 ml of the so obtained solution, 0.5 ml of I.S. solution was added. RESULTS AND DISCUSSION During the experiments, the color of the substance changed from white through yellow to a pale brown. The analysis of concentration changes of CTN indicates that in dry air (RH ~ 0%) the decomposition of CTN in Biotrakson and Tartriakson proceeded according to the first-order reaction. The plots ln c t = f (t) are linear (Figure 1) and the observed rate constants (Table 1) were calculated using Microsoft Æ Excel 2002 according to the equation ln c t = c 0 ñ k t, where c 0 and c t represent the concentrations of substrate at time 0 and t, respectively; k is the first-order rate constant. The degradation of CTN in a humid environment (RH > 50%) proceeded according to the model of an autocatalytic reaction (Figure 2). The rate constants of the autocatalytic first-order reaction relative to the substrate concentrations (Tables 2 and 3) were calculated from the equation ln (1-α)/α = ñ k t + C where (1-α)/α = c t /(c 0 ñ c t ); c 0 and c t represent the substrate concentrations at t = 0 and t; c 0 ñ c t represent the product concentrations at time = t, C denotes the constant related to the induction period. Similar changes of the kinetic equations depending on storage conditions were observed for other cefalosporins, such as cefetamet pivoxyl hydrochloride (8), cefosulodine sodium (9ñ10), cefoperazone sodium (9ñ10) and cefazoline sodium (9ñ10). The semilogarithmic plots of c t /(c 0 ñ c t ) = f (t) were linear and their slopes a = ñ k (Figure 3). For the interpretation of the dependence ln c = f (t) and ln c t /(c 0 ñ c t ) = f (t), the following statistical parameters of the respective equations were calculated using Microsoft Æ Excel 2002: y = ax + b; a± a; b ± b, standard errors: S a, S b, S y and the coefficient of the linear correlations r. The values of a± a and b ± b were obtained for f = n ñ 2 degrees of freedom with α = Thermodynamic parameters The determined rate constants were employed for the calculation of the Arrhenius dependence: ln k i = ln A ñ (E a /R) (1/T). The relationships ln k i = f (1/T) were linear for both reparations at RH = 0% and RH = 76.4%. The slopes of these plots were used to calculate activation energy, enthalpy and entropy of the reaction (Tables 1 and 2). The effect of humidity The effect of relative air humidity (>50%) on the stability of CTN in Biotrakson and Tartriakson (Table 3) was described by the following equations: Tartriakson ln k i = a RH% + b = ( ± ) RH% ñ (15.49 ± 0.14); Biotrakson ln k i = a RH% + b = ( ± ) RH% ñ (16.99 ± 1.96). The values of ln A and E a are higher in dry air than at RH = 76.4% for both preparations. The thermodynamic parameters for the degradation of CTN in Biotrakson and Tartriakson were statistically comparable, but the times t 0.5 and t 0.1 were shorter for Biotrakson. This was caused by a longer induction period in the case of Tartriakson. The values a and b in the equation ln k i = a RH% + b were statistically comparable for Biotrakson and Tartriakson. REFERENCES 1. Neu H.C., Meropol N.J., Kwung P.F.: Antimicrob. Agents Chemother. 19, 414 (1981). 2. Smith B.R.: Am. J. Hosp. Pharm. 40, 1024 (1983). 3. Scott E., Dranitsaris W., Dranitsaris G.: Can. J. Hosp. Pharm. 40, 161 (1987). 4. Martinez-Pacheco R., Vila-Jato J.L., Gomez- -Amoza J.L.: Il Farmaco 42, 131 (1988).

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