What is the expected therapeutic outcome of the simultaneous administration of two medications?

Polypharmacy is defined as the use of multiple medications by a patient, with 5–10 medications usually accepted as the cutoff.

From: Geriatric Rehabilitation, 2018

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Author	Drug	Indication	Protocol	Number of studies	Adverse effects	Study design	“drug monitoring” included in search	Information sources	RoB/Quality assessment of studies	Meta analysis
Cooney 2016 [8]	Aminophylline	Asthma	No	12	Yes	No restrictions	No	Medine, CINAHL, Cochrane Central, and Web of Science	Cochrane tool for assessment of risk of bias [35], CASP tool [36]	No
Sparshatt 2009 [10]	Amisulpride	Schizophrenia/schizoaffective disorder	No	10	Yes	No restrictions	No	Embase, Medline and PubMed	None	No
Sparshatt 2010 [14]	Aripirazole	No specific diagnosis	No	8	No	No restrictions	Yes	Embase, Medline, and PubMed	None	No
Knight 2008 [11]	Mycophenolate Mofetil	Transplant patients	No	12	Yes	RCTs, Observational studies	No	Medline, Embase, Cochrane Central, Transplant Library, Clinical trial registries	None	No
Zuk 2009 [15]	Mycophenolate Mofetil	Heart transplant	No	7	No	No restrictions	Yes	Medline Embase	None	No
Bishara 2013 [16]	Olanzapine	Schizophrenia/schizoaffective disorder/bipolar disorder	No	30	Yes	No restrictions	Yes	PubMed, Medline, Embase	None	Yes
Konidari 2014 [9]	Thiopurine	IBD	No	15	Yes	RCTs, Observational studies	Yes	PubMed, Medline, UK national health system database	NICE defined criteria for quality assessment of case series [37]	No
Moreau 2014 [17]	Thiopurine	IBD	Yes	17	No	No restrictions	Yes	Medline, Cochrane Library, DirectScience, and Google Scholar	Nonea	Yes
Osterman 2006 [12]	Thiopurine	IBD	No	12	No	No restrictions	No	Medline, PubMed Plus	None	Yes
Prybylski 2015 [13]	Vancomycin	S. aureus bacteraemia	No	14	No	Observational studies	No	PubMed	None	Yes

RoB Risk Of bias, IBD Inflammatory Bowel Disease, RCT Randomised controlled trial, CENTRAL Central Register of Controlled Trials
aMoreau et al. used the MOOSE consensus statement to assess reporting quality, but do not report the results of their assessment