Drug-drug interactions (DDIs) are types of adverse drug events (ADEs) which can occur when the effect of a drug is altered by another drug that is taken concurrently and results in a qualitative and/or quantitative change in drug action(Stockley’s, 2010).
It can be major, moderate and minor interactions based on its severity. Major DDIs can cause a life threating or a last longing damage. Moderate DDIs call for additional treatment and minor DDIs do not have a significant effect on the therapy (Varma MV, Pang KS, Isoherranen N, 2015).
According to the mechanisms by which drugs interact with each other, DDIs can a classified as pharmaceutical, pharmacokinetic and pharmacodynamics(Bolhuis MS, Panday PN, PrangerAD, 2011).
DDIs may have desirable, over and above undesirable or harmful effects(Varma MV, Pang KS, Isoherranen N, 2015), increase or decrease the efficacy of one drug on another, increase the toxicity of medications or result in treatment failure(Bjornsson T, Callaghan J, Einolf H, 2003; Bolhuis MS, Panday PN, PrangerAD, 2011).
DDI is an emerging threat to public health(Kothari N, 2014) which can occur within a couple of minutes or can take several weeks to develop (Jacob S, 2011). Various studies suggest that cardiovascular patients, Human Immunodeficiency Virus infected patients and psychiatric patients are more often reported with potential DDIs as compared to patients with other diseases. The possible reasons behind include older age, multiple drug regimens, pharmacokinetic and pharmacodynamic nature of drugs used in cardiology, and the influence of heart disease on drug metabolism (Diksis et al, 2019; Behailu Terefe Tesfaye et al, 2017; Haftay Berhane Mezgebe et al, 2017).
Most of DDIs occurred because of inadequate knowledge of prescribers’ on DDIs or poor recognition of the relevance of DDIs by prescribers(Heininger-Rothbucher D, Bischinger S, Ulmer H, Pechlaner C, Speer G, 2001; Ko Y, Malone DC, Skrepnek GH, Armstrong EP, Murphy JE, Abarca J, Rehfeld RA, Reel SJ, 2008).
When different prescribers prescribe a drug in the treatment of the same patient, the number of prescribed drugs may increase, and it may be difficult for the prescriber to keep track of the prescribed medications. This will lead to an increased risk of potential DDIs(Bjerrum L, Lopez Valcarcel BG, 2008).
Even though prescribing of multiple drugs for one patient may be logical and necessary practice for patients particularly those who have comorbid disease, physicians should take into account the incidence of potential DDIs for patients taking multiple drugs(Grattagliano I, Portincasa P, D’Ambrosio G, Palmieri VO, 2010).The incidence of potential DDIs is close to 40% in patients taking 5 drugs, and exceeds 80% in patients taking seven or more drugs(Grattagliano I, Portincasa P, D’Ambrosio G, Palmieri VO, 2010; Kapp PA, 2013).
DDIs are more prevalent in patients receiving a combination two or more drugs(Astrand E, Astrand B, Antonov K, 2007; Juurlink DN, Mamdani M, Kopp A, Laupacis A, 2003) and more frequent in patients who are elder, hospitalized for a longer period of time, and/or receive more drugs per day(Janković SM, Pejčić AV, Milosavljevic MN, 2018; Obreli-Neto PR, Nobili A, de Oliveira Baldoni A, 2012; Romagnoli KM, Nelson SD, Hines L, 2017).
Even though the concomitant use of a combination of drugs often increases therapeutic effectiveness, certain combinations are harmful(Teixeira J, Crozatti M, Santos C, 2012). But all potential DDIs aren’t clinically significant(Goldberg RM, Mabee J, Chan L, 1996).
Clinically significant DDIs may cause a potential harm to patients, harmful outcomes and resulting in an estimated cost of more than $1 billion per year to governmental health care system expenditure(Qorraj-Bytyqi H, Hoxha R, Krasniqi S, Bahtiri E, 2012).The risk of DDI rose from 13% for patients taking two medications to 82% for patients taking seven or more medications(Cristiano Moura C, Acurcio F, 2009).
Hospitalized patients are more likely to be affected by DDIs because of severe and multiple illnesses, comorbid conditions, chronic therapeutic regimens, poly-pharmacy and frequent modification in therapy(Zwart-van-Rijkom JEF, Uijtendaal EV, Ten Berg MJ, Van Solinge WW, 2009). Among hospitalized patients, elderly patients are at higher risk of potential DDIs and occurrence of potential DDIs ranges from 3 to 69%, depending on the specific area and population. This increased prevalence was found to be related to presence of multiple chronic illnesses, use of multiple medications and altered pharmacokinetics in the elderly patients(Wang JK, Herzog NS, Kaushal R, Park C, Mochizuki C, 2007).
Some studies report that hospitalized patients receive an average of 10 different drugs(Zopf Y, Rabe C, Neubert A, Hahn A, 2008). The greater the severity of the patient’s disease the higher the number of drugs prescribed, and the greater the likelihood of adverse drug interactions happened(Joshua L, Devi P, 2009).
In addition to elder patients, Hospitalized pediatric patients face higher risk of drug induced problems due to wide-ranging of patient ages and body-weights, limited physiologic reserve, medications dosing errors and inaptitude to properly communicate with healthcare workers(Wang JK, Herzog NS, Kaushal R, Park C, Mochizuki C, 2007).
Generally, the risk factors that are associated with potential DDIs are age, increased number of drugs (poly-pharmacy), multiple prescribers, comorbid conditions, chronic therapeutic regimens, and frequent modification in therapy and hospitalization (Kapp PA, 2013).
Studies have suggested that drug use can be improved and potential DDIs can be prevented by better communication among patients, physicians, and pharmacists(Carter BL, Lund BC, Hayase N, 2002). In addition to this, DDIs can be prevented by avoiding multiple drug treatment (poly-pharmacy) and weighing the potential benefits of drug combinations against the risk of the occurrence of clinically significant DDIs.
A very few number of studies are available regarding the evaluation of potential DDIs in Sub-Saharan region of Africa(Lubinga SJ, 2011). This is also a problem in Ethiopian health care system.
In Ethiopia, now a days polypharmacy is increased due to comorbid conditions in the hospital health care system(Berha AB, 2018; Sisay M., Mengistu G., Molla B., 2017), a large number of patients are hospitalized and there is a high possibility for DDIs. Furthermore, due to economic problems, the probability of monitoring patients with comorbid diseases using sophisticated instruments is not feasible causing the patient to DDIs.
As a result, potential DDIs causing serious risk to patient health. Therefore, this study attempted to review and quantitatively estimate the prevalence of potential DDIs and associated risk factors in hospitals, both among inpatients and outpatients in Ethiopia.