Polypharmacy (PP) is a common problem in modern medicine, especially known to affect patients with chronic diseases such as multiple sclerosis (MS). With an increasing number of drugs taken, the risk of potential drug–drug interactions (pDDIs) is rising. This study aims to assess the prevalence and clinical relevance of polypharmacy and pDDIs in patients with MS. Pharmacological data of 627 patients with MS were entered into two drug–drug-interaction databases to determine the number and severity of pDDIs for each patient. The patients were divided into those with and without PP (total PP and prescription medication PP [Rx PP]). Of the 627 patients included, 53.3% and 38.6% had total PP and Rx PP, respectively. On average, every patient took 5.3 drugs. Of all patients, 63.8% had at least one pDDI with a mean of 4.6 pDDIs per patient. Less than 4% of all pDDIs were moderately severe or severe. Medication schedules should be checked for inappropriate medication and for possible interacting drugs to prevent pDDIs. Physicians as well as pharmacists should be more sensitive towards the relevance of pDDIs and know how they can be detected and avoided.

Background: Multiple sclerosis (MS) is the most common immune-mediated demyelinating disease in younger adults. Patients with MS (PwMS) are vulnerable to the presence of potential drug–drug interactions (pDDIs) and potential drug–food interactions (pDFIs) as they take numerous medications to treat MS, associated symptoms and comorbidities. Knowledge about pDDIs and pDFIs can increase treatment success and reduce side effects. Objective: We aimed at determining the frequency and severity of pDDIs and pDFIs in PwMS, with regard to polypharmacy. Methods: In the cross-sectional study, we analysed pDDIs and pDFIs of 627 PwMS aged ⩾18 years. Data collection was performed through patient record reviews, clinical examinations and structured patient interviews. pDDIs and pDFIs were identified using two DDI databases: Drugs.com Interactions Checker and Stockley’s Interactions Checker. Results: We identified 2587 pDDIs (counted with repetitions). Of 627 PwMS, 408 (65.1%) had ⩾ 1 pDDI. Polypharmacy (concomitant use of ⩾ 5 drugs) was found for 334 patients (53.3%). Patients with polypharmacy (Pw/P) were found to have a 15-fold higher likelihood of having ⩾ 1 severe pDDI compared with patients without polypharmacy (Pw/oP) (OR: 14.920, p < 0.001). The most frequently recorded severe pDDI was between citalopram and fingolimod. Regarding pDFIs, ibuprofen and alcohol was the most frequent severe pDFI. Conclusion: Pw/P were particularly at risk of severe pDDIs. Age and educational level were found to be factors associated with the occurrence of pDDIs, independent of the number of medications taken. Screening for pDDIs/pDFIs should be routinely done by the clinical physician to increase drug safety and reduce side effects.

Background: Patients with multiple sclerosis (MS) often undergo complex treatment regimens, resulting in an increased risk of polypharmacy and potential drug-drug interactions (pDDIs). Drug interaction databases are useful for identifying pDDIs to support safer medication use.Objective: To compare three different screening tools regarding the detection and classification of pDDIs in a cohort of MS patients. Furthermore, we aimed at ascertaining sociodemographic and clinical factors that are associated with the occurrence of severe pDDIs.Methods: The databases Stockley’s, Drugs.com and MediQ were used to identify pDDIs by screening the medication schedules of 627 patients. We determined the overlap of the identified pDDIs and the level of agreement in pDDI severity ratings between the three databases. Logistic regression analyses were conducted to determine patient risk factors of having a severe pDDI.Results: The most different pDDIs were identified using MediQ (n = 1,161), followed by Drugs.com (n = 923) and Stockley’s (n = 706). The proportion of pDDIs classified as severe was much higher for Stockley’s (37.4%) than for Drugs.com (14.4%) and MediQ (0.9%). Overall, 1,684 different pDDIs were identified by at least one database, of which 318 pDDIs (18.9%) were detected with all three databases. Only 55 pDDIs (3.3%) have been reported with the same severity level across all databases. A total of 336 pDDIs were classified as severe (271 pDDIs by one database, 59 by two databases and 6 by three databases). Stockley’s and Drugs.com revealed 47 and 23 severe pDDIs, respectively, that were not included in the other databases. At least one severe pDDI was found for 35.2% of the patients. The most common severe pDDI was the combination of acetylsalicylic acid with enoxaparin, and citalopram was the drug most frequently involved in different severe pDDIs. The strongest predictors of having a severe pDDI were a greater number of drugs taken, an older age, living alone, a higher number of comorbidities and a lower educational level.Conclusions: The information on pDDIs are heterogeneous between the databases examined. More than one resource should be used in clinical practice to evaluate pDDIs. Regular medication reviews and exchange of information between treating physicians can help avoid severe pDDIs.

Background: Although effective contraception is strongly recommended during the therapy of women with multiple sclerosis (MS) with some immunomodulatory drugs, unplanned pregnancies still occur. Adequate medication management is essential to avoid foetal harm in the event of an unplanned pregnancy. Objective: The aim was to screen for medications used in women of childbearing age with MS that may pose a risk of side effects on foetal development. Methods: Sociodemographic, clinical and medication data were collected from 212 women with MS by structured interviews, clinical examinations and medical records. Using the databases from Embryotox, Reprotox, the Therapeutic Goods Administration and on the German summaries of product characteristics, we assessed whether the taken drugs were potentially harmful regarding the foetal development. Results: The majority of patients (93.4%) were taking one or more drugs for which a possible harmful effect on the foetus is indicated in at least one of the four databases used. This proportion was even higher in patients who used hormonal contraceptives (birth control pills or vaginal rings) (PwCo, n = 101), but it was also quite high in patients who did not use such contraceptives (Pw/oCo, n = 111) (98.0% and 89.2%, respectively). PwCo were significantly more likely to take five or more medications with potential foetal risk according to at least one database than Pw/oCo (31.7% versus 6.3%). PwCo were also more severely disabled (average Expanded Disability Status Scale score: 2.8 versus 2.3) and more frequently had comorbidities (68.3% versus 54.1%) than Pw/oCo. Conclusion: Data on the most commonly used drugs in MS therapy were gathered to study the risk of possible drug effects on foetal development in female MS patients of childbearing age. We found that the majority of drugs used by patients with MS are rated as having a potential risk of interfering with normal foetal development. More effective contraception and special pregnancy information programmes regarding the therapy management during pregnancy should be implemented to reduce potential risks to mother and child. Plain Language Summary Use of drugs not recommended during pregnancy by women with multiple sclerosis Introduction: Patients with multiple sclerosis (MS) often have to take different drugs simultaneously. During the therapy with some immunomodulatory drugs, effective contraception is strongly recommended. Nevertheless, unplanned pregnancies occur regularly in women with MS. Methods: Here, we investigated whether the 212 patients included in this study were taking drugs with known possibility of harm to the development of an unborn child. This was done using four different drug databases. Results: A subset of 111 patients was not taking hormonal contraceptives (birth control pills or vaginal rings). Of those, 99 patients were taking at least one drug that is not recommended during pregnancy according to at least one of the four databases. Most of the medications taken have the potential to affect normal foetal development. Conclusion: To ensure safe use of medications, the patients should be reminded of the importance of effective contraception.