Potency boost of a Mycobacterium tuberculosis dihydrofolate reductase inhibitor by multienzyme F420H2-dependent reduction.

Triaza-coumarin (TA-C) is a Mycobacterium tuberculosis (Mtb) dihydrofolate reductase (DHFR) inhibitor with an IC50 (half maximal inhibitory concentration) of ∼1 µM against the enzyme. Despite this moderate target inhibition, TA-C shows exquisite antimycobacterial activity (MIC50, concentration inhibiting growth by 50% = 10 to 20 nM). Here, we investigated the mechanism underlying this potency disconnect. To confirm that TA-C targets DHFR and investigate its unusual potency pattern, we focused on resistance mechanisms. In Mtb, resistance to DHFR inhibitors is frequently associated with mutations in thymidylate synthase thyA, which sensitizes Mtb to DHFR inhibition, rather than in DHFR itself. We observed thyA mutations, consistent with TA-C interfering with the folate pathway. A second resistance mechanism involved biosynthesis of the redox coenzyme F420 Thus, we hypothesized that TA-C may be metabolized by Mtb F420-dependent oxidoreductases (FDORs). By chemically blocking the putative site of FDOR-mediated reduction in TA-C, we reproduced the F420-dependent resistance phenotype, suggesting that F420H2-dependent reduction is required for TA-C to exert its potent antibacterial activity. Indeed, chemically synthesized TA-C-Acid, the putative product of TA-C reduction, displayed a 100-fold lower IC50 against DHFR. Screening seven recombinant Mtb FDORs revealed that at least two of these enzymes reduce TA-C. This redundancy in activation explains why no mutations in the activating enzymes were identified in the resistance screen. Analysis of the reaction products confirmed that FDORs reduce TA-C at the predicted site, yielding TA-C-Acid. This work demonstrates that intrabacterial metabolism converts TA-C, a moderately active "prodrug," into a 100-fold-more-potent DHFR inhibitor, thus explaining the disconnect between enzymatic and whole-cell activity.

The INN global nomenclature of biological medicines: A continuous challenge.

Medicines are assigned International Nonproprietary Names (INN) by the World Health Organization (WHO), pursuing the aim to increase patient safety. Following scientific developments in drug discovery and biotechnology, the number of biological medicines is constantly growing and a surge in INN applications for them has been observed. Pharmacologically active biological substances have a complex structure and mechanism of action posing new challenges in selecting names that appropriately reflect such properties. As a consequence, existing nomenclature naming schemes may need to be revised and new ones developed. This review reports on the recently implemented policies for naming fusion proteins, monoclonal antibodies, advanced therapy substances that cover gene and cell therapy, virus-based therapies as well as vaccines and vaccine-like substances. Different approaches, based on the use of a one-word versus a two-word naming scheme, have been developed for different categories of biological substances highlighting a major and still not completely resolved issue, i.e. how to assign a name that is both informative, short and euphonic.

Fused Heterocyclic Systems with an s-Triazine Ring. 34. Development of a Practical Approach for the Synthesis of 5-Aza-isoguanines.

Purine isosteres present excellent opportunities in drug design and development. Using isosteres of natural purines as scaffolds for the construction of new therapeutic agents has been a valid strategy of medicinal chemistry. Inspired by the similarity to isoguanine, we attempted to develop a practical method for the preparation of 5-aza-isoguanines. Several synthetic approaches were explored to establish a robust general protocol for the preparation of these compounds. The significant difference in the reactivity of the C-5 and C-7 electrophilic centers of 1,2,4-triazolo[1,5-a][1,3,5]triazines (5-azapurines) towards nucleophiles was demonstrated. The most practical and general method for the preparation of 5-aza-isoguanines involved a regioselective reaction of ethoxycarbonyl isothiocyanate with a 5-aminotriazole. The intramolecular ring closure of the resulted product followed by the S-methylation afforded 7-methylthio-2-phenyl-1,2,4-triazolo[1,5-a][1,3,5]triazin-5-one, which could be effectively aminated with various amines. The resulted 5-aza-isoguanines resemble a known purine nucleoside phosphorylase inhibitor and could be interesting for further investigations as potential anticancer agents.

A novel shogaol analog suppresses cancer cell invasion and inflammation, and displays cytoprotective effects through modulation of NF-κB and Nrf2-Keap1 signaling pathways.

Natural compounds containing vanilloid and Michael acceptor moieties appear to possess anti-cancer and chemopreventive properties. The ginger constituent shogaol represents one such compound. In this study, the anti-cancer potential of a synthetic novel shogaol analog 3-phenyl-3-shogaol (3-Ph-3-SG) was assessed by evaluating its effects on signaling pathways. At non-toxic concentrations, 3-Ph-3-SG suppressed cancer cell invasion in MDA-MB-231 and MCF-7 breast carcinoma cells through inhibition of PMA-activated MMP-9 expression. At similar concentrations, 3-Ph-3-SG reduced expression of the inflammatory mediators nitric oxide (NO), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and prostanglandin-E2 (PGE2) in RAW 264.7 macrophage-like cells. Inhibition of cancer cell invasion and inflammation by 3-Ph-3-SG were mediated through suppression of the nuclear factor-kappaB (NF-κB) signaling pathway. The 3-Ph-3-SG also demonstrated cytoprotective effects by inducing the antioxidant response element (ARE)-driven genes NAD(P)H quinone oxidoreductase-1 (NQO1) and heme oxygenase-1 (HO-1). Cytoprotection by 3-Ph-3-SG was achieved at least partly through modification of cysteine residues in the E3 ubiquitin ligase substrate adaptor Kelch-like ECH-associated protein 1 (Keap1), which resulted in accumulation of transcription factor NF-E2 p45-related factor 2 (Nrf2). The activities of 3-Ph-3-SG were comparable to those of 6-shogaol, the most abundant naturally-occurring shogaol, and stronger than those of 4-hydroxyl-null deshydroxy-3-phenyl-3-shogaol, which attested the importance of the 4-hydroxy substituent in the vanilloid moiety for bioactivity. In summary, 3-Ph-3-SG is shown to possess activities that modulate stress-associated pathways relevant to multiple steps in carcinogenesis. Therefore, it warrants further investigation of this compound as a promising candidate for use in chemotherapeutic and chemopreventive strategies.

Synthesis, anti-thymidine phosphorylase activity and molecular docking of 5-thioxo-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-ones.

In our lead finding program, a series of 5-thioxo-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-ones and their 5-thio-alkyl derivatives were designed and synthesized which contained different substituents at ortho-position of 2-phenyl ring attached to the fused ring structure. The preliminary pharmacological evaluation demonstrated that the synthesized compounds exhibited a varying degree of inhibitory activity towards thymidine phosphorylase (TP), comparable to reference compound, 7-Deazaxanthine (7-DX, 2) (IC50 value=42.63 µM). The study also inferred that the ortho-substituted group at the phenyl ring and 5-thio-alkyl moiety imparted steric hindrance effects in the binding site of the enzyme, leading to a reduced inhibitory response. In addition, compound 3a was identified as a mixed-type inhibitor of TP. Moreover, computational docking study was performed to illustrate the important structural information on the plausible ligand-enzyme binding interactions.

Building a successful platform for interprofessional education for health professions in an Asian university.

Implementing Interprofessional Education (IPE) across health professions schools is challenging. Within an Asian context, academic staff at the National University of Singapore designed a platform to create a sustainable IPE effort. A two-pronged approach was developed to ensure adequate coverage of key concepts relating to IPE within each involved faculty. The Interprofessional Core Curricula (ICC) component ensures that each health profession student will be exposed to IPE concepts in their required curriculum. Interprofessional Enrichment Activities (IEA) incentivize further cross-faculty participation and progress within the IPE competency framework. Best practices and success factors were identified, while lessons learned led to further improvements. Adoption of this approach can help circumvent well-known barriers to implementation.

Computational prediction of state anxiety in Asian patients with cancer susceptible to chemotherapy-induced nausea and vomiting.

State anxiety, a risk factor for chemotherapy-induced nausea and vomiting (CINV), is a subjective symptom and difficult to quantify. Clinicians need appropriate anxiety measures to assess patients' risks of CINV. This study aimed to determine the anxiety characteristics that can predict CINV based on computational analysis of an objective assessment tool. A single-center, prospective, observational study was carried out between January 2007 and July 2010. Patients with breast, head and neck, and gastrointestinal cancers were recruited and treated with a variety of chemotherapy protocols and appropriate antiemetics. Chemotherapy-induced nausea and vomiting characteristics and antiemetic use were recorded using a standardized diary, whereas patients' anxiety characteristics were evaluated using the Beck Anxiety Inventory. Principal component (PC) analysis was performed to analyze the anxiety characteristics. A subset known as principal variables, which had the highest PC weightings, was identified for patients with and without complete response, complete protection, and complete control. Chemotherapy-induced nausea and vomiting events and anxiety characteristics of 710 patients were collated; 51%, 30%, and 20% were on anthracycline-, oxaliplatin-, and cisplatin-based therapies, respectively. Most patients suffered from delayed CINV, with decreasing proportions achieving complete response (58%), complete protection (42%), and complete control (27%). Seven symptoms (fear of dying, fear of the worst, unable to relax, hot/cold sweats, nervousness, faintness, numbness) were identified as potential CINV predictors. This study demonstrates the usefulness of PC analysis, an unsupervised machine learning technique, to identify 7 anxiety characteristics that are useful as clinical CINV predictors. Clinicians should be aware of these characteristics when assessing CINV in patients on emetogenic chemotherapies.

3D-QSAR Study on dihydro-1,3,5-triazines and their spiro derivatives as DHFR inhibitors by comparative molecular field analysis (CoMFA).

A 3D-QSAR/CoMFA was performed for a series of triazine and its spiro derivative based DHFR inhibitors displaying IC(50) values ranging from 0.002 to 58.8 µM. Analyses resulted in a reliable computational model with the parameters of n=46, r(2)=0.986, q(2)=0.724, SE=0.164, F=275.889. It is shown that the steric and electrostatic properties predicted by CoMFA contours can be related to the DHFR inhibitory activity. The predictive ability of the resultant model was evaluated using a test set comprised of 18 molecules and the results show that the CoMFA model is able to correctly predict the poor inhibitory activities of the compounds in the testing set. This model is a significant guide to trace the features that really matter especially with respect to the design of novel compounds.

Regioselective synthesis of pyrimido[1,2-a][1,3,5]triazin-6-ones via reaction of 1-(6-oxo-1,6-dihydropyrimidin-2-yl)guanidines with triethylorthoacetate: observation of an unexpected rearrangement.

A novel thermal rearrangement, involving pyrimidine ring opening and subsequent ring closure leading to recyclization of the system, was identified in the reaction of (6-oxo-1,6-dihydropyrimidin-2-yl)guanidines 3 (where NR(1)R(2) = NH(2), NH alkyl, NH aralkyl, NHCH(2)Ph(R)) with triethyl orthoacetate, affording 4-substituted-2-methyl-6H-pyrimido[1,2-a][1,3,5]triazin-6-ones 6 and their ring opened products. However, no such rearrangement was observed with (6-oxo-1,6-dihydropyrimidin-2-yl)guanidines 3 bearing a tertiary amino or anilino substituent (i.e. where NR(1)R(2) = N(CH(3))(2), indoline, morpholino, NHAr). As expected, 2-substituted-4-methyl-6H-pyrimido[1,2-a][1,3,5]triazin-6-ones 4 were obtained as the final products. Experimental structural determination and theoretical studies were carried out to get an understanding of the observed thermal rearrangement. In addition, an attempt to obtain similar pyrimido[1,2-a][1,3,5]triazin-6-ones using N,N-dimethylacetamide dimethyl acetal (DMA-DMA) as one carbon inserting synthon had furnished triazine ring annulated product 14 bearing N,N-dimethyl enamino substituent at position 4 as a result of further reaction with a second molecule of DMA-DMA.

Effects of chemotherapy and psychosocial distress on perceived cognitive disturbances in Asian breast cancer patients.

BACKGROUND: There is conflicting evidence on the effect of chemotherapy and psychosocial distress on perceived cognitive changes in cancer patients. OBJECTIVE: To compare the severity of perceived cognitive disturbance in Asian breast cancer patients receiving chemotherapy and those not receiving chemotherapy, and identify clinical characteristics associated with perceived cognitive disturbances. METHODS: A cross-sectional, observational study was conducted at the largest cancer center in Singapore. Breast cancer patients receiving chemotherapy and not receiving chemotherapy completed the Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog), European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30), and Beck Anxiety Inventory to assess their perceived cognitive functioning, health-related quality of life, and anxiety, respectively. Multiple regression was conducted to delineate the factors associated with perceived cognitive disturbances. RESULTS: A total of 85 breast cancer patients receiving chemotherapy and 81 not receiving chemotherapy were recruited. Chemotherapy patients experienced more fatigue (QLQ-C30 fatigue scores: 33.3 vs 22.2 points; p = 0.005) and moderate-to-severe anxiety (21.9% vs 8.6%; p = 0.002) compared to non-chemotherapy patients. Non-chemotherapy patients reported better perceived cognitive functioning than those who received chemotherapy (FACT-Cog scores: 124 vs 110 points, respectively; p < 0.001). Chemotherapy and endocrine therapy were strongly associated with perceived cognitive disturbances (p < 0.001 and 0.021, respectively). The interacting effect between anxiety and fatigue was moderately associated with perceived cognitive disturbances (ß = -0.29; p = 0.037). CONCLUSIONS: Chemotherapy and endocrine treatment were associated with significant cognitive disturbances among Asian breast cancer patients. Psychosocial factors could be used to identify cancer patients who are more susceptible to cognitive disturbances in the clinical setting.

Acute and Chronic Administrations of Rheum palmatum Reduced the Bioavailability of Phenytoin in Rats: A New Herb-Drug Interaction.

The rhizome of Rheum palmatum (RP) is a commonly used herb in clinical Chinese medicine. Phenytoin (PHT) is an antiepileptic with narrow therapeutic window. This study investigated the acute and chronic effects of RP on the pharmacokinetics of PHT in rat. Rats were orally administered with PHT (200 mg/kg) with and without RP decoction (single dose and seven doses of 2 g/kg) in a crossover design. The serum concentrations of PHT, PHT glucuronide (PHT-G), 4-hydroxyphenytoin (HPPH), and HPPH glucuronide (HPPH-G) were determined by HPLC method. Cell line models were used to identify the underlying mechanisms. The results showed that coadministration of single dose or multiple doses of RP significantly decreased the C(max) and AUC(0-t) as well as the K(10) of PHT, PHT-G, HPPH, and HPPH-G. Cell line studies revealed that RP significantly induced the P-gp-mediated efflux of PHT and inhibited the MRP-2-medicated transport of PHT and HPPH. In conclusion, acute and chronic coadministrations of RP markedly decreased the oral bioavailability of PHT via activation of P-gp, although the MRP-2-mediated excretion of PHT was inhibited. It is recommended that caution should be exercised during concurrent use of RP and PHT.

Shogaols at proapoptotic concentrations induce G(2)/M arrest and aberrant mitotic cell death associated with tubulin aggregation.

Shogaols have been previously reported to induce cancer cell death via multiple mechanisms, among which one analog 6-shogaol has been reported to cause microtubule damage through specific reaction with sulfhydryl groups in tubulin. In this study, a series of shogaols with different side chain lengths (4-, 6-, 8- and 10-shogaol) was synthesized and evaluated for antiproliferative activity in HCT 116 colon carcinoma and SH-SY5Y neuroblastoma cells. 4- and 6-shogaol were identified as lead compounds possessing the strongest antiproliferative activity. In the soft agar assay, the lead shogaols displayed dose-dependent inhibition on cancer cell colony formation under anchorage-independent conditions. Using HCT 116 as the selected cancer cell line, the molecular events linking shogaols-induced G(2)/M cell cycle arrest to apoptosis characterized by caspase 3 and PARP cleavage were investigated. At sublethal concentrations, the halt at G(2)/M phase was alleviated along time and cells survived. Conversely, proapoptotic concentrations of 4- and 6-shogaol induced irreversible G(2)/M arrest that was at least in part associated with down-regulation of cell cycle checkpoint proteins cdk1, cyclin B and cdc25C, as well as spindle assembly checkpoint proteins mad2, cdc20 and survivin. A dose- and time-dependent accumulation of insoluble tubulin in the insoluble fractions of cell lysates provided evidence that G(2) checkpoint failure led to disruption of microtubule turnover. In summary, our results conclude that shogaols cause apoptosis by inducing aberrant mitosis at least through the attenuation of cell cycle and spindle assembly checkpoint proteins.

Nanoparticulate delivery system targeted to tumor neovasculature for combined anticancer and antiangiogenesis therapy.

PURPOSE: Herein, we designed a nanoparticulate combined delivery system decorated on the surface with RGD peptide, and encapsulating paclitaxel (PTX) and combretastatin A4 (CA4) as the respective anticancer and antiangiogenesis agent in the nanoparticle. METHODS: PTX and CA4 were co-encapsulated into the biocompatible PLGA, followed by solvent evaporation to form solid nanoparticle. The cRGDfK peptide was then conjugated onto the nanoparticle surface with EDC/NHS chemistry. RESULTS: The developed nanoparticles (NPs) were found uniform in size and well dispersed in buffers. The cellular uptake of such NPs could be efficiently detected as early as 20 min after incubation. In 24-h incubation, the encapsulated PTX could induce caspase 3/7-dependent apoptosis at 50 nM, whereas the CA4-loaded NPs could disrupt tubulin structure at 2.5 µM. The targeted dual drug-loaded nanoparticle achieved significant tumor growth suppression in vivo compared to the control from day 8 (P < 0.05). Histological results revealed that the targeted dual drug nanoparticle led to dramatic tumor vasculature disruption, significant cancer cell apoptosis and cell proliferation inhibition in the mouse model. CONCLUSION: These findings indicate that the targeted dual drug nanoparticulate delivery system encompassing both antiangiogenesis and anticancer effects can be a potential candidate in cancer therapy.

Synthesis and antimicrobial activity of N¹-benzyl or N¹-benzyloxy-1,6-dihydro-1,3,5-triazine-2,4-diamines.

The emergence and spread of multidrug-resistant strains of Staphylococcus aureus and Mycobacterium tuberculosis are generating a threat to public health worldwide. In the current study, a series of N(1)-benzyl and N(1)-benzyloxy-1,6-dihydro-1,3,5-triazine-2,4-diamine derivatives were synthesized and investigated for their antimicrobial activity against S. aureus, and Mycobacterium smegmatis which is taxonomically related to M. tuberculosis. Most of the compounds exhibited good activity against M. smegmatis as determined by comparison of diameters of the zone of inhibition of test compounds and standard antibiotics. Compound 7o showed potent antimycobacterial activity against M. smegmatis without mammalian DHFR inhibition liability. The results from this study indicate that 1-benzyl derivatives of 1,6-dihydro-1,3,5-triazine-2,4-diamines may be used as lead compounds for the discovery of antimycobacterial agents.

7-(4-Fluoro-benzyl-amino)-2-phenyl-1,2,4-triazolo[1,5-a][1,3,5]triazin-5-amine methanol disolvate.

The 1,2,4-triazolo[1,5-a][1,3,5]triazine system in the title compound, C(17)H(14)FN(7)·2CH(3)OH, is essentially planar, with an r.m.s. deviation of 0.0215 Å. The attached phenyl ring lies almost in the mean plane of the heterocyclic core [dihedral angle = 3.56 (4)°]. In the crystal, centrosymmetric inversion dimers connected via inter-molecular N-H⋯N hydrogen bonds between H atom of the primary amino group and the triazine N atom [R(2) (2)(8) graph-set motif] form sheets parallel to (010). A second set of dimers connected via N-H⋯F hydrogen bonds between the other H atom of the primary amino group and the F atom forms an R(2) (2)(24) graph-set motif linking the sheets. Methanol solvent mol-ecules are packed in channels running along the [010] direction.

Comparative assessment of competency frameworks for pharmacists in the Western Pacific region including the potential for a regional framework.

OBJECTIVES: To assess the potential for a regional competency framework for pharmacists in the Western Pacific using the Global Competency Framework (GbCF) as a reference. METHODS: Mixed-methods approach used a self-administered survey and semi-structured interviews of 13 countries to evaluate the perceived benefits, existence and content of competency frameworks. KEY FINDINGS: Variations in structure, components and emphasis of the four frameworks that do exist indicate significant tailoring to local requirements. Based on these four and the GbCF, 32 competencies allocated into four themes has been proposed. CONCLUSION: Varying national requirements mitigate against a single regional competency framework.

Harnessing the internet cloud for managing drug interactions with chemotherapy regimens in patients with cancer suffering from depression.

UNLABELLED: Concomitant use of anticancer drugs (ACDs) and antidepressants (ADs) in the treatment of depression in patients with cancer may result in potentially harmful drug-drug interactions (DDIs). It is crucial that clinicians make timely, accurate, safe and effective decisions regarding drug therapies in patients. The ubiquitous nature of the internet or "cloud" has enabled easy dissemination of DDI information, but there is currently no database dedicated to allow searching of ACD interactions by chemotherapy regimens. We describe the implementation of an AD interaction module to a previously published oncology-specific DDI database for clinicians which focuses on ACDs, single-agent and multiple-agent chemotherapy regimens. METHODS: Drug- and DDI-related information were collated from drug information handbooks, databases, package inserts, and published literature from PubMed, Scopus and Science Direct. Web documents were constructed using Adobe software and programming scripts, and mounted on a domain served from the internet cloud. RESULTS: OncoRx is an oncology-specific DDI database whose structure is designed around all the major classes of ACDs and their frequently prescribed chemotherapy regimens. There are 117 ACDs and 256 regimens in OncoRx, and it can detect over 1 500 interactions with 21 ADs. Clinicians are provided with the pharmacokinetic parameters of the drugs, information on the regimens and details of the detected DDIs during an interaction search. CONCLUSION: OncoRx is the first database of its kind which allows detection of ACD and chemotherapy regimen interactions with ADs. This tool will assist clinicians in improving clinical response and reducing adverse effects based on the therapeutic and toxicity profiles of the drugs.

Antifolate and antiproliferative activity of 6,8,10-triazaspiro[4.5]deca-6,8-dienes and 1,3,5-triazaspiro[5.5]undeca-1,3-dienes.

Two series of triazaspiroalkanedienes, bearing a substituted phenoxy propyloxy side chain, were identified as potent mammalian DHFR inhibitors. One series has a 6,5-spiro bicyclic ring system and the other series has a 6,6-spiro bicyclic system. Both series were synthesized and tested for in vitro mammalian DHFR inhibitory activity and antiproliferative activity against A549 human lung-cancer cells. Compound 3c showed the highest antiproliferative activity against A549 cells with an IC(50) value of 27.1nM. Rescue experiment confirmed its antifolate antiproliferative mechanism. The excellent antifolate and antiproliferative activity of selected analogues presented in this study warrants further investigation as potential leads in the anticancer drug discovery.

An onco-informatics database for anticancer drug interactions with complementary and alternative medicines used in cancer treatment and supportive care: an overview of the OncoRx project.

PURPOSE: Cancer patients are at high risk of manifesting interactions from use of anticancer drugs (ACDs) and complementary and alternative medicines (CAMs). These interactions can result in sub-therapeutic effects or increased toxicities which may compromise the outcome of chemotherapy. It is important for practitioners to gain convenient access to ACD-CAM interaction information so as to make better-informed decisions in daily practice. This paper describes the creation of an oncology database (OncoRx) that documents ACD-CAM interactions, including traditional Chinese medicines (TCMs) that are commonly used for cancer treatment, prevention, and supportive care therapy. METHODS: Information regarding ACDs, CAMs, and drug interactions were collated from 14 sources, inclusive of hardcopy and online resources, and input into a modified web server with a database engine and a programming interface using a combination of software and programming scripts. RESULTS: OncoRx currently contains a total of 117 ACDs and 166 CAMs. Users are able to search for interactions based on various CAM uses: cancer treatment or prevention, immune-system-related, alopecia, nausea, and vomiting, peripheral neuropathy and pain, inflammation, fatigue, and non-cancer related. Pharmacokinetic data on ACDs and CAMs, characteristics of CAMs based on TCM principles, and drug interaction parameters such as effects, mechanisms, evidences, and proposed management plans, are shown in the search results. CONCLUSION: OncoRx is an oncology database which detects ACD interactions. It is currently able to detect interactions with CAMs. It is hoped that OncoRx will serve as a useful resource to clinicians, educators, trainers, and students working in the oncology setting.

Drug-drug interactions between oral antiepileptics and oral anticancer drugs: implications to clinicians.

BACKGROUND: Existing research has suggested that there can be potential drug-drug interaction (DDI) between antiepileptic drugs (AED) and anticancer drugs (ACD). However, information on the prevalence of patients on concurrent oral AED and oral ACD is limited. METHODS: A retrospective study was conducted at the National Cancer Centre Singapore. Prevalence was calculated by identifying prescriptions with both oral AED and oral ACD from the outpatient prescription database over three years. Prevalence and physicians' prescribing patterns were evaluated. Co-prescription was defined as medications that were prescribed by the same physician on the same day. Potentially interacting combinations were further detected using an existing database, OncoRx (www.onco-informatics.com). RESULTS: 42,810 prescriptions that contained at least one oral ACD were identified from the database. The number and prevalence of prescriptions that had a combination of oral ACD and AED were 274 and 0.64%, respectively, with the majority (82.8%) of the AED-oral ACD pairs being co-prescribed. Per patient, the average number of exposure days to the AED-oral ACD pair was 19.5 days annually. Fifty-one (18.6%) prescriptions were identified as containing potentially interacting AED-oral ACD pairs. DISCUSSION: There is a relatively low prevalence of AED-oral ACD combined exposure in the population we sampled; however, the combined exposure is long enough to produce clinically important DDI effects.