Iraqi J Pharm Sci, Vol.31(1) 2022 Valerian-carbamazepine interaction DOI: https://doi.org/10.31351/vol31iss1pp220-224 220 Effect of Oral Administration of Valerian Extract at Different Doses on Pharmacokinetic Parameters of Carbamazepine in Rabbits Issam Mohammed Abushammala*,1 *Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Al-Azhar University/Gaza, , Palestine. Abstract Carbamazepine (CBZ) is a narrow therapeutic index drug used in the treatment of trigeminal neuralgia and psychiatric disorders. Valerian (VAL) is a popular herbal product which should be prescribed to treat insomnia and anxiety. The study was designed to investigate the presence of significant pharmacokinetic (PK) interaction between Valerian (VAL) at different concentrations on Carbamazepine (CBZ) pharmacokinetic parameters in healthy male rabbits. In an in vivo, parallel-randomized controlled trial, the rabbits in three groups "first (control), second and third" were given oral doses of CBZ (50 mg/kg), for "second and third" groups (as test groups) rabbits were given (20 and 40 mg/kg/day) of the VAL respectively, as suspension in normal saline for eight consecutive days. On the eighth day, CBZ was co-administered an hour after adding the last dose of VAL suspension. Venous blood samples (1.0-1.5 mL) were obtained from rabbits' ears' marginal vein at predetermined different periods. The plasma of this blood separation was done using centrifugation and stored at -80°C, prior to analysis by using CBZ chemiluminescent enzyme immunoassay detection kit. Different PK parameters such as Cmax, tmax, t½, ke, AUC0-24 and AUC0-∞ were determined for the three groups, applying Statistical testing (ANOVA). The results showed statistical insignificant differences for all PK parameters among the three groups with (p˃0.05). The findings showed that VAL at both concentrations is not likely to interfere with PK parameters related to CBZ, Further confirmation in humans shoud be done before these findings are applied to patient care. Keywords: Carbamazepine, CYP3A4, Valerian, Herb-drug interaction Pharmacokinetic parameters. على عوامل بجرعات مختلفة حشيشة الهرثير التعاطي الفموي لمستخلص تأ حركية الكاربامازيبين في االرانب 1*،عصام محمد ابو شمالة . غزة، فلسطين –جامعة األزهر ، كلية الصيدلة م الصيدالنيات والصيدلة الصناعية،قس* الخالصة بتركيزات مختلفة على ( VAL) مستخلص حشيشة الهربين ( PK) فى عوامل حركية الدواءصممت الدراسة للتحقق من وجود تداخل معشاة في ذكور األرانب السليمة( CBZ) للكاربامازبين عوامل حركية الدواء ، متوازية ، أعطيت مستخدمين ارانب سليمة صحيا ذات شواهد الثالث المجموعات في والثالثة)األرانب والثانية من ( األولى فموية للمجموعتين ( كلغم /ملغم CBZ (50)جرعات بالنسبة والثالثة"؛ " الثانية ل ملحي عادي لمدة في محلو (VAL) مستخلص حشيشة الهرمن ( يوم / كلغم /ملغم 40و 20)أعطيت األرانب على التوالي ( كمجموعات اختبار) متتالية قاعدة على أيام إعطاء. ثمانية تمت ، الثامن اليوم من CBZ في جرعة آخر إضافة من ساعة بعد مشترك الهربشكل حشيشة مستخلص VAL).) من الوريد الهامشي آلذان األرانب في فترات مختلفة ومن ثم تم إجراء فصل الدم ( مل 1.5-1.0)تم الحصول على عينات الدم الوريدي درجة مئوية قبل التحليل باستخدام مجموعة الكشف المناعي لإلنزيم الكيميائي 80-بالبالزما باستخدام الطرد المركزي وتم تخزينه في درجة حرارة للمجموعات الثالث ومن ثم تم تطبيق 0and AUC 24-0, AUCek½, , tmax, tmaxC-∞ ثل مختلفة م PKتم تحديد معلمات . الخاصة للكاربامازبين بين المجموعات عوامل حركية الدواءلجميع ( p˃0.05)أظهرت النتائج فروق ذات داللة إحصائية غير معنوية (. ANOVA)االختبار اإلحصائي ، يجب إجراء مزيد CBZالمتعلقة بـ PKفي كال التركيزين من غير المحتمل أن يتداخل مع معلمات مستخلص حشيشة الهرتظهر النتائج أن . الثالث . من التجارب قبل تطبيق هذه النتائج في رعاية المرضى الحركية الدوائية. معامالت ، التفاعالت الدوائية ، مستخلص حشيشة الهر، الكاربامازيبين :المفتاحية الكلمات Introduction Herbal-drug interactions can be characterized as either pharmacodynamic or pharmacokinetic (PK) by nature. Pharmacodynamic interactions may occur when constituents of herbal products have either synergistic or antagonist activity concerning a conventional drug meanwile, PK interactions result from alteration of absorption, distribution, metabolism, or elimination of a conventional drug by herbal product or other food supplements (1,2). 1Corresponding author E-mail: issam.abushammala@uv.es Received: 22/6/2021 Accepted: 6/10 /2021 Iraqi Journal of Pharmaceutical Science https://doi.org/10.31351/vol31iss1pp220-224 Iraqi J Pharm Sci, Vol.31(1) 2022 Valerian-carbamazepine interaction 221 Carbamazepine is a common drug used for treating partial and tonic-colonic seizers (3). Cytochrome P450 (CYP450) monooxygenase is a superfamily of hemoproteins, which is responsible for the phase I metabolism of various xenobiotics and some endogenous substances as steroids. Nearly 70–80% of all prescribed drugs are metabolized by the CYP system. CYP3A4 is involved in CBZ metabolic sequences. Carbamazepine has a narrow range of therapy and might show drug interaction with several drugs either by induction or inhibition of CYP3A4. Despite its clinical popularity, CBZ possesses several PK properties which make it a possible candidate to interact with substances upon co- administration, including synthetic drugs, pharmaceutical herbs and food. CBZ is classified not only as an effective inducing agent of CYP450 system, but also as autoinduction agent (4-8). Valerian (VAL) is the common name given to the crude drug consisting of underground organs of species of (Valerianaceae). The major components of VAL include the monoterpenebornyl acetate and the sesquiterpene valerenic acid which, in addition to other types of sesquiterpene, are characteristic features of the species. The constituents of the volatile oil are variable due to population differences in genetics and environmental factors. VAL -as a traditional herb- was used to treat insomnia and anxiety. It is also considered as the largest attended non- prescribed sedative in European countries (9,10). Herb/CBZ interaction was catchy and crucial topic for many researchers all over the world (11,12). Therefore, interaction potency should be taken into consideration upon using herbs as medication to avoid reduction in drug efficiency and/or increase the side effects of concomitantly administered drugs (13). Possible herb-drug interaction of VAL-CBZ is still underestimated. This research was conducted to study the effect of co-administration of VAL at different doses on PK parameters of CBZ in rabbits. Subjects and Methods Animals Eighteen New Zealand strains of adult male rabbits weighted (3.1-3.4 kg) and aged (7-9) months were divided into three groups (six subjects in each) and were used as animal model for the current drug – herb PK interaction study. All rabbits were kept under standard laboratory conditions in a 12-hour light/dark cycle at 25°C ± 2°C provided with pellet diet with free acces to water (ad libitum) and were fasted overnight before the experiments. Study design and blood sampling The study design was parallel-randomized controlled trial. Eighteen male rabbits were assigned into three groups. In the first group (control group), rabbits were given orally a volume equivalent to CBZ (50 mg/kg) from a 2% oral suspension (Tegretol, Novartis). Post dosing venous blood samples (1.0-1.5 mL) obtained from ear vein of the rabbits using special cannula (21G) at different time periods (0.50, 1.0, 1.50, 2.00, 2.50, 3.50, 4.0, 6.00, 12.00, 18.0 and 24.00 hr) (14). In the second and third groups (test groups), the rabbits were given a volume of CBZ 2% oral suspension also in a dose of (50 mg/kg) at the same conditions as in the first group concurrently with volumes equivalent to (20 and 40 mg/kg/day, repectively) VAL suspension. This suspension was commercially prepared by pulverizing the film coated tablets of VAL Relaxin, Lab. Pharma Trenker) in normal saline. VAL suspension was given for eight continuous days. On the eighth day, CBZ was administered one hour after administration of the last dose of VAL suspension, and blood was collected from rabbits from the second and the third groups at the same periods mentioned above. Plasma was collected by centrifugation of samples and was stored at (-80°C) until analysis. The analysis was performed by CBZ detection kits (CLEIA) and Immulite 1000 Immunoassay System. PK parameters determination The plasma level -time profile of CBZ was constructed for the control and herb treated groups. The PK parameters of CBZ in the control and test groups were calculated using Model -Independent Approach (Non-Compartmental Model (NCM)). WinNonlin Professional Software (Version 6.3, Pharsight Corporation, Cary, NC) and (GraphPad Prism versión 4.00, San Diego, CA, USA) were used in the calculation and statistical analysis of the following PK parameters: Maximum plasma concentration (Cmax), time to reach maximum plasma concentration (tmax), elimination rate constant (Ke), elimination half-life (t1/2), area under plasma concentration -time curve up to 24 hours (AUC0–24) and to the infinit time (AUC0–∞) for the control and herb treated groups. Statistical analysis Data were presented as Mean (plasma conc. Of CBZ) ± SD. Differences in PK parameters of CBZ upon administering without VAL (first group) and with VAL suspension at different concentrations (second and third groups) were assessed by analysis of variance (ANOVA) using SPSS program (version 22.0) taking 95 % confidence interval and significant statistical differences as p value ˂0.05. Iraqi J Pharm Sci, Vol.31(1) 2022 Valerian-carbamazepine interaction 222 Results This study was carried out to determine the influence of VAL at two different concentrations (20 and 40 mg/kg/day) on PK parameters of CBZ when given concurrently. The PK parameters of CBZ in the control group (first group) were compared to those of the test groups treated with VAL 20 and 40 mg/kg/day (second and third groups respectively). Plasma level -time profiles of CBZ in the three groups are shown in Figure 1. The calculated PK parameters: Cmax, tmax, t1/2, Ke, AUC0-24 and AUC0-∞ of the three groups were mentioned in table 1. In this study, Cmax of CBZ (first group) was 6.64±1.12 µg/mL and tmax was 1.95±0.22 h. The rabbits treated with VAL 20 mg/kg/day (second group) produced Cmax and tmax of 6.82±1.25 µg/mL and 2.11±0.27 h, respectively. A slight, but statistically nonsignificant, increase of Cmax and tmax of CBZ were found when VAL was co- administered with CBZ (second group). The systemic exposures according to AUC0-∞ showed nonsignificant differences between the two groups (94.32±11.7 µg.hr/mL vs. 73.71±28.1 µg.hr/mL; p=0.063). Other PK parameters including t1/2, Ke and AUC0-24 showed no significant differences between both groups (Table 1). Figure 1. Concentration -time profile of CBZ without VAL (First group) and with VAL (Second and third groups) in rabbits. Table 1. Pharmacokinetic Parmeters of CBZ without VAL (First group) and with VAL (Second and Third groups) in Rabbits. PK Parameters Groups Mean ± SD P-value Cmax (µg/mL) First group 6.64±1.12 0.770¥ 0.296§ Second group 6.82±1.25 Third group 6.41±1.13 tmax (hr) First group 1.95±0.22 0.054¥ 0.726§ Second group 2.11±0.27 Third group 2.10±0.20 t1/2 (hr) First group 13.70±4.40 0.055¥ 0.131§ Second group 10.30±2.87 Third group 8.91±2.47 Ke (hr-1) First group 0.054±0.012 0.181¥ 0.052§ Second group 0.053±0.025 Third group 0.081±0.018 AUC0-24 (µg*hr/mL) First group 76.49±13.85 0.360¥ 0.090§ Second group 62.54±21.27 Third group 55.53±20.50 AUC0-∞ (µg*hr/mL) First group 94.32±11.7 0.063¥ 0.173§ Second group 73.71±28.1 Third group 64.30±27.1 n= 6 rabbits for each group. (¥) : p value of the differences between the first group and the second group. (§) : p value of the differences between the first group and the third group. T im e ( h ) P l a s m a c o n c e n t r a t i o n o f C B Z (  g / m l ) 0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0 2 2 2 4 0 2 4 6 8 F i r s t g r o u p ( C B Z 5 0 m g / k g ) S e c o n d g r o u p ( V a l 2 0 m g / k g / d a y + C B Z 5 0 m g / k g ) T h i r d g r o u p ( V a l 4 0 m g / k g /d a y + C B Z 5 0 m g / k g ) Iraqi J Pharm Sci, Vol.31(1) 2022 Valerian-carbamazepine interaction 223 The estimated model-independent PK parameters of CBZ alone (first group) and co- administered with VAL 40 mg/kg/day (third group) were also listed in table 1. In this case, the differences in Cmax and tmax of CBZ between first and third groups were insignificant since, ( p > 0.05). Furthermore, other PK parameters including t1/2 and ke of CBZ in the first and third groups were also, statistically insignificant. Besides, no significant differences were recorded between the first and third groups regarding the systemic exposures defined by AUC0-24 and AUC0-∞ (Table 1). Discussion Since the antiepileptic CBZ drug is given on a short-term basis, the opportunity of a significant clinical interaction between CBZ and co- administered substances is common. The clinical sequence of interactions may be lack of efficiency, toxicity, unexpected effects, and vague side effects (15,16). Regarding the lack of studies investigating VAL-CBZ interactions, the present study was conducted. All rabbits enrolled in this study had finished the study period without any deviation. The isoform CYP3A4 of CYP450 is being a significant enzyme that is responsible for biotransformation of 70% of the drugs in use today. As antiepileptic regimens are normally given on a long-term basis, the opportunity of a clinically significant interaction between CBZ and co- administered substances is considerably high. Herbal medicines, dietary supplements, and food may interact with CBZ pharmacokinetically and/or pharmacodynamically which leads to potential clinical consequences. One of the contributing factors towards increasing the incidence of herb- drug interaction is the increased popularity of herbal medicines (17). Some herbal products such as Cassia auriculata Linn., piperine (an active compound in Piper longum Linn.), Platycodonis Radix, and Polygonum cuspidatum were demonstrated to increase the plasma level/oral bioavailability of CBZ through decreasing the metabolism of CBZ or improving gastric solubility of CBZ meanwhile, others like ginkgo biloba, Hu-gan-ning pian, Jia- wei-xiao-yao-san, and Xiao-yao-san decreased the plasma level/oral bioavailbaility of CBZ through increasing the metabolism of CBZ via CYP 3A4 induction (18-24). The results of the PK interaction study between CBZ and VAL commercial dry extract at two different doses (20 and 40 mg/kg/day) in rabbits showed no statistical differences in PK parameters (p>0.05). Similar results were found by Jiang and his collaborators when studied the effect of berberine on PK of CYP3A4 and P-gp substrates (25), who found that a statistically insignificant differences after a 2-week pretreatment with bebeerine. The PK interaction study between Saiko- ka-ryukotsu-borei-to and CBZ in rats published by Ohnishi and his collaborators showed a lack of PK interactions (26). Similar findings were ontained by Burstein et al. who demonstrated that treatment with St John’s Wort for 14 days did not further induce the clearance of CBZ (27). In other study Abushammala et al. demonstrated that CBZ had no significantly different pharmacokinetic (PK) parameters, namely, Cmax, tmax, AUC0-24, AUC0-∞, t½, and Ke, when it was given alone or concurrently with Panax Ginseng (28). Conclusion Herb-drug interaction is of great importance for patient safety, especially with the increased popularity of herbal medicines. PK interaction of CBZ was recorded when it was co- administered with some herbs. In this study, VAL spspension that was prepared from Valerian Root Extract showed minimal effect on PK profile of CBZ. Further research should also be performed by using higher VAL doses, a longer treatment duration and a larger sample size before the confirmation of the present results in humans. Ethical Statement The study was approved and performed under ethical principles laid down by the Faculty of Pharmacy, Al-Azhar University-Gaza, Palestine. Conflict of Interest No conflicts of interest relevant to this article. Acknowledgments The authors wish to express deepest gratitude and thanks to all staff in the Faculty of Pharmacy at Al-Azhar University-Gaza for their kind support, especially for Dr. Mai Ramadan for her scientific support and consultancy. References 1. Fugh-Berman A. Herb-drug interactions. Lancet. 2000; 355(9198):134-138. 2. Chavez ML, Jordan MA, Chavez PI. Evidence- based drug-herbal interactions. Life Sci. 2006;78(18):2146-2157. 3. Nolan SJ, Marson AG, Weston J, Tudur SC. Carbamazepine versus phenobarbitone monotherapy for epilepsy: an individual participant data review. Cochrane Data base Syst Rev. 2015;23(7):CD001904. 4. Viktoriia B, Galia Z, Sidika S, Pham G, Vladimir Z, Martin R. Tissue-specific expression and activity of cytochrome P450 1A and 3A in rainbow trout (Oncorhynchus mykiss). Toxicology Letters. 2021;341:1-10. 5. Kane GC, Lipsky JJ. Drug-grapefruit juice interactions, Mayo Clinic Proceedings. 2000;75(9):933–942. 6. Ekor M. The growing use of herbal medicines: issues relating to adverse reactions and challenges in monitoring safety. Front Pharmacol. 2014;4:177. Iraqi J Pharm Sci, Vol.31(1) 2022 Valerian-carbamazepine interaction 224 7. Chen L, Chen Y, Chou M, Lin M, Yang L, Yen K. Pharmacokinetic Interactions between Carbamazepine and the Traditional Chinese Medicine Paeoniae Radix. Biol. Pharm. Bull. 2002;25(4):532-535. 8. Bibi Z. Role of cytochrome P450 in drug interactions. Nutrition & metabolism 2008;5:27. 9. Houghton PJ. The scientific basis for the reputed activity of valerian. Journal of Pharmacy and Pharmacology. 1999;51:505- 512. 10. Krystal AD, Ressler I. The use of valerian in neuropsychiatry. CNS Spectrums. 2001;6:841- 847. 11. Fong SYK., Gao Q, Zuo Z. Interaction of carbamazepine with herbs, dietary supplements, and food: A systematic review. Evidence-Based Complementary and Alternative Medicine. 2013;2013:898261. 12. Patsalos PN, Perucca E. Clinically important drug interactions in epilepsy: general features and interactions between antiepileptic drugs. Lancet Neurol. 2003;2(6): 347-356. 13. Tang J, Song X, Zhu M. Study on the pharmacokinetics drug-drug interaction potential of Glycyrrhiza uralensis, a traditional Chinese medicine, with lidocaine in rats. Phytother. Res. 2009;23:603–607. 14. Parasuraman S, Raveendran R, Kesavan R. Blood sample collection in small laboratory animals. Journal of Pharmacology and Pharmacotherapeutics. 2010; 1(2):87–93. 15. Svein I, Johannessen Cecilie JL. Antiepileptic Drug Interactions-Principles and Clinical Implications. Current Neuropharmacology. 2010;8:254-267. 16. Landmark CJ, Patsalos PN. Interactions between antiepileptic drugs and herbal medicines. Bol Latinoam Caribe Plant Med. 2008;7:109–118. 17. Mohamed MF, Frye RF. Effects of herbal supplements on drug glucuronidation. Review of clinical, animal and in vitro studies. Planta Medica. 2011;77(4):311–321. 18. Thabrew I, Munasinghe J, Chackrewarthi S, Senarath S. The effects of Cassia auriculata and Cardiospermum halicacabum teas on the steady state blood level and toxicity of carbamazepine. Journal of Ethnopharmacology. 2004;90(1):145–150. 19. Pattanaik S, Hota D, Prabhakar S, Kharbanda P, Pandhi P. Pharmacokinetic interaction of single dose of piperine with steady-state carbamazepine in epilepsy patients. Phytotherapy Research. 2009;23(9):1281– 1286. 20. Liu P., Wei L. Effect of Platycodon grandiflorum on the blood concentration of carbamazepine in rabbits. Evaluation and Analysis of Drug-Use in Hospitals of China. 2008;8(5):366-369. 21. Chi YC, Lin SP, Hou YC. A new herb-drug interaction of Polygonum cuspidatum, a resveratrol-rich nutraceutical, with carbamazepine in rats. Toxicology and Applied Pharmacology. 2012;263(3):315–322. 22. Chandra RH, Rajkumar M, Veeresham C. Pharmacokinetic interaction of ginkgo biloba with carbamazepine. Planta Medica. 2009;(4):454. 23. Zhang ZJ, Kang WH, Li Q, Tan Q. The beneficial effects of the herbal medicine free and easy wanderer plus (FEWP) for mood disorders: double-blind, placebo-controlled studies. Journal of Psychiatric Research. 2007;41(10):828–836. 24. Li W, Tan Q, Zhang Z. Randomized double- blind controlled clinical trial of the combination of Xiao-yao-san and carbamazepine in the treatment of bipolar disorders. Zhong Guo Lin Chuang Yao Li Xue Za Zhi. 2005;21:336–340. 25. Qiu W, Jiang XH, Liu CX, Ju Y, Jin JX. Effect of Berberine on the Pharmacokinetics of Substrates of CYP3A and P-gp. Phytother. Res. 2009;23:1553–1558. 26. Ohnishi N, Nakasako S, Okada k, Umehara S, Takara k, Nagasawa k. et al. Interactions between Traditional Herbal and Western Medicines. Lack of Pharmacokinetic Interactions between Saiko-ka-ryukotsu-borei- to and Carbamazepine in Rats. European Journal of Drug Metabolism and Pharmacokinetics. 2001;26(1, 2):129-135. 27. Burstein A, Horton R, Dunn T, Alfaro R, Piscitelli S, Theodore W. Lack of effect of St John’s Wort on carbamazepine pharmacokinetics in healthy volunteers. Clin. Pharmacol Ther. 2000;68:605-612. 28. Abushammala IM, El-Shaikh Ali FK, Abu Shammaleh KF, Taha MM, Miqdad MY. Effect of Panax ginseng on Carbamazepine Pharmacokinetics in Rabbits. Turk J Pharm Sci. 2021;25:18(1):17-20. 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