Buster Mannheimer

Adjunct senior lecturer

My research involves the adverse effects following drug treatment. Lately, two major aims have been to study warfarin interactions and different aspects of drug related hyponatremia.

About me

I was born in 1973 and educated at the University of Gothenburg taking my doctors exam in 2002. I then performed my specialization at Södersjukhuset, qualifying as a specialist in Internal Medicine in 2007 and as a specialist in Endocrinology and Diabetes in 2010. Since my specialization I have continued working at Södersjukhuset and been a consultant since 2016.

I defended my thesis at Karolinska Institutet in 2009 becoming an Associate Professor in 2016. Since 2018 I’m part time employed as the Director of Doctoral Education of the Department of Clinical Science and Education at Karolinska Institutet.

Research description

In 2009 I defended my thesis ”Drug-related problems with special emphasis on drug-drug interactions”. The thesis includes pharmacogenetic, pharmacokinetic as well as epidemiologic aspects on mainly adverse effects due to the treatment with psychotropic drugs. Since then I have moved towards a mainly register based research. Several projects have included the use of the Swedish Prescribed Drug Register (SPDR) and investigated prescription patterns but also associations with clinical outcome. 

Combining the SPDR with Auricula and Journalia, registries containing data on individuals  treated with anticoagulantia we have established a cohort of over 100 000 patients treated with warfarin. The cohort enables a unique epidemiologic therapeutic drug monitoring approach, efficiently targeting the effects of any added drug with regard to changes in INR and warfarin doses. So far, we have published data on the effects of initiating carbamazepine and amiodarone. Four of five warfarin-treated patients in whom cotreatment with carbamazepine was initiated experienced subtherapeutic anticoagulative effect within 3–5 weeks. The warfarin dose was subsequently increased by 49 %. For amiodarone, a powerful inhibitor of enzymes of importance for warfarin metabolism, the opposite effect was evident with supratherapeutic  INR and a subsequent average 25 % compensatory dose decrease.  This knowledge is important to avoid severe bleedings or thromboembolic complications due to changes in anticoagulation caused by interactions. Onwards we plan to investigate the effect of several additional drugs.

Another project focuses on different aspects of hyponatremia. We recently established a cohort of over 14 000 individuals hospitalized due to hyponatremia. Using a case control design we studied the associations between antidepressants and hospitalization due to hyponatremia. The results indicated a strong association between selective serotonin reuptake inhibitors (SSRIs) and venlafaxine, and hospitalization due to hyponatremia exclusively related to newly initiated treatment. Consequently, in patients with clinically significant hyponatremia with newly initiated treatment with SSRI or venlafaxine, an alternative treatment should be considered. For patients with ongoing antidepressant treatment, other causes should be explored. The project has a lot of potential. One future aim is to investigate the effects of other drugs. Another is to follow the cohort over time which will be interesting in several ways. For example we plan to compare the cases and controls with regard to mortality.