In vitro-In vivo Studies on Drug Interaction Between Ketotifen and Commonly Prescribed Drugs

Abstract

The objectives of the present study were to investigate the drug-drug interactions between ketotifen fumarate and some commonly prescribed drugs. Their interactions were identified and confirmed by UV, IR, DSC and HPLC followed by TLC. The in vitro results were correlated with in vivo model to see whether the desired drug concentration could attain into the blood stream or not. Finally attempts have been taken to find out the effects of these complexes on the liver and kidney. Each of the drugs absorption was analyzed in the UV-VIS region. The spectra of pure drugs as well as their 1:1, 1:2 and 2:1 mixtures of ketotifen & paracetamol, ketotifen & domperidone, ketotifen & desloratidine, ketotifen & amoxicillin, ketotifen & metformin, ketotifen & chlorpheniramine, ketotifen & theophylline, ketotifen & salbutamol and ketotifen & diclophenac sodium were studied at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8 and 7.4. At both gastric and intestinal pHs, a sharp breakdown was observed in the curves. Similarly when ketotifen was mixed with metformin, a sharp change was observed in the curve at pHs 0.4, 1.2, 2.8 & 7.4 which indicated drug-drug interactions, whereas the absence of such particular breakdown in the curve of ketotifen and metformin mixture at pHs 2.0, 6.0 and 6.8 revealed the absence of drug interactions. Again when various concentrations comprising 1x10 -5 M to 9x10 -5 M of ketotifen were interacted with chlorpheniramine, sharp changes in the curve were observed at pHs 0.4, 6.0 and 6.8, which demonstrated the presence of drug-drug interactions. On the other hand, the absence of breakdown in the curve of ketotifen and chlorpheniramine mixture at pHs 1.2, 2.0, 2.8 and 7.4 revealed the absence of drug interactions. The stability constant values (k = 1x10 -2 ) for the particular interaction was determined by graphical representation of Ardon’s plot. The stability constants of ketotifen & paracetamol (5.67, 6.36, 7.21, 14.84, 17.97, 38.35, 24.79 at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8, 7.4 respectively), ketotifen & domperidone (77.89, 84.27, 10.01, 28.95, 60.23, 21.85, 114.82 at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8, 7.4 respectively), ketotifen & desloratidine (14.54, 14.07, 16.73, 5.56, 17.49, 5.16, 3.06 at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8, 7.4 respectively), ketotifen & theophylline (6.8, 7.4, 3.5, 4.8, 9.6, 5.7, 18.4 at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8, 7.4 respectively) and ketotifen & amoxicillin (19.8, 13.7, 2.30, 35.7, 14.1, 8.3, 51.6 at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8, 7.4 respectively) were found to be relatively higher at gastric and intestinal pHs. This reflects that there might be relatively stronger complex formation due to interaction between the mentioned drugs. But relatively low stability constant values were seen when the interaction occurred between ketotifen & chlorpheniramine (0.7256, 0.2895, 1.0683, 1.6807, 1.6827, 0.0507, 0.2834 at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8, 7.4 respectively), ketotifen & diclofenac (0.068, 0.057 at pHs 6.8, 7.4 respectively) and ketotifen & metformin (0.03, 0.55, 0.05, 0.01, 0.09, 0.01, 0.77) at pHs 0.4, 1.2, 2.0, 2.8, 6.0, 6.8, 7.4 respectively). If the formation constant is reasonably favorable, two straight lines of different slopes that intersect at a mole ratio corresponding to the mixing ratio in the complex are obtained. In the IR study, the possible interaction between ketotifen fumarate and amoxicillin trihydrate showed characteristic peaks. The peaks of C-Cl (696.33 cm -1 ) was shifted to higher wave number at 703.08 cm -1 and C-O-C group at 1082.11 cm -1 was shifted to higher wave number in the complex at 1099 cm -1 (C-O-C stretching); The peaks of alkenes at 3040 cm -1 was shifted to 3056 cm -1 (=CH). Simultaneously the peaks of isocyanates (-N=C=O) at 2270 cm -1 and carboxylic 3336.99 cm -1 (O-H) were shifted to lower wave numbers in the complex at 2263cm -1 and 3327 cm -1 . On the other hand the interaction between ketotifen fumarate and diclofenac sodium showed that the peaks of acid phosphines at 839.07 cm -1 (P-H stretching) was shifted to higher wave number in the complex at 854.5 cm -1 , the peaks of alkyl halides of 1386.88 cm -1 , amides of 1575.91 cm -1 , amides of 1652.1 cm -1 aromatic group having wave number of 2970.5 cm -1 were showed characteristic peaks in the complexes at 1354.09 cm -1 , 1587.48 cm -1 , 1647.28 cm -1 and 2957 cm -1 respectively. Similarly in case of ketotifen & salbutamol interactions showed characteristic peaks at the peaks of C-H (aromatic group), C-O-C (ether group), C-C (ketone) and O-H (carboxylic acid group) at 838.11 cm -1 , 1085 cm -1 , 1201.7 cm -1 , 2925.17 cm -1 were shifted to higher wave numbers in the complexes at 855.47 cm -1 (C-H stretching), 1099.47 cm -1 (C-O-C stretching), 1224.85 cm -1 (C-C stretching) and 2937.71 cm -1 (O-H). Similarly the interaction between ketotifen and theophylline showed that the peaks of phosphine oxides group at 1180 cm -1 (P=O stretching) and alkenes group at 1378 cm -1 (C-H) were shifted to lower wave numbers in the complex at 1151 cm -1 (P=O stretching) and 1362.77 cm -1 (C-H stretching). On the other hand, peak of amides of 1559.51 cm -1 (N-H stretching) was shifted to higher wave number in the complex at 1588.19 cm -1 (N-H). In the DSC study (ketotifen, domperidone and ketotifen & domperidone mixture) ketotifen exhibited sharp endothermic peak at 193.08 0 C. But the ketotifen-domperidone complex exhibited a sharp new peak at 120.02 0 C (-1.74 mW/mg). On the other hand, DSC of the samples (ketotifen, metformin and ketotifen & metformin mixture) were performed and observed that ketotifen-metformin complex exhibited a sharp new peak at 123.04 0 C (-2.61 mW/mg). But the mixture of ketotifen and theophylline exhibited no sharp peak. The R f values of ketotifen (0.44) and domperidone (0.53) was found to be completely different from ketotifen-domperidone mixture (0.38). The R f values of ketotifen (0.49) and metformin (0.51) was found to be completely different from ketotifen-metformin mixture (0.39) which conclude the stability of the complex for both mixtures. However in case of HPLC the complex which was formed between ketotifen & theophylline and ketotifen & metformin could have been partly dissociated in aqueous medium used to dissolve the sample for HPLC analysis. The multiple comparison table shows that there is a significant difference in absorbances at various mentioned times (30 minutes, 60 minutes, 120 minutes & 180 minutes) to complete the drug interaction between the group that took the single drug as well as mixtures (ketotifen & metformin, ketotifen & paracetamol, ketotifen & salbutamol, ketotifen & amoxicillin, ketotifen & diclofenac) The results were expressed as mean ± SEM values. A probability value less than 0.05 (p < 0.05) was defined to be significant. The results of investigation of hepatotoxicity of combination drug therapy were compared with single drug sample ketotifen. But the groups which receive the combination drug samples ketotifen & metformin (67.5 + 1.44 IU/L) and ketotifen & theophylline (68.5 + 2.5 IU/L) showed a significant increase in SGPOT, and showed a significant decrease of ATPN levels in ketotifen & theophylline mixture (7.0 + 0.07 IU/L) and in ketotifen & metformin mixture (6.13 + 0.73 IU/L). The creatinine concentration was found to be 1.4 mg/dl in case of normal control but it was raised to 3.6 mg/dl when mixture of ketotifen and theophylline was administered. Now we can conclude that the patients having motion sickness and patients who had been suffering from diabetes should take a precaution during coadmintration of ketotifen fumarate & domperidone and ketotifen fumarate & metformin hydrochloride..