DIURETICS INTERACTIONS WITH MEDICATIONS USED IN THE MANAGEMENT OF CONGESTIVE HEART FAILURE AND OTHER CO-MORBID CONDITIONS: AN INDICATION FOR CONSTANT DRUG THERAPY MONITORING AND VIGILANCE

*John David Ohieku and Muhammad Al-Amin Usman

ABSTRACT

Background: Many patients are worried receiving medications that have adverse drug interactions that will further affect their health status. Objectives: The objectives were to assess potential interactions between three classes of diuretic with other medications and to evaluate the potential clinical outcomes as well as to identify patients that may require constant monitoring and vigilance. Methods: The cross-sectional and prospective study involve the evaluation of drug interaction between diuretics and other medications using online drug interaction software checkers developed by Medscape.com, Drug.com, Drugbank.com and Epocrates online. Results: The proportion of patients recommended for diuretics among the middle aged adult was 41.7%, 34.3% and 20.0% for loop, K-sparing and thiazide diuretics respectively. Drugs co-used with loop diuretic when compared with the total number of such drugs in the entire study were as high as 75% each for atorvastatin, nifedipine, captopril and carvedilol; and as low in thiazide combinations with amiodarone (4.8%), CaCO3(6.4% ), calcitriol (7.5%) and allopurinol (13.6%). Out of 23 paired interactions that occurred between loop diuretic and other medications, 21(91.3%) were single interaction while 2(8.7%) were double interactions. With K-sparing diuretic interactions and other medications 18(90.0%) were single while 1(5.0%) each were double and quartet interactions respectively. In thiazide diuretics single interaction were 19(90.5%) while double and triple interactions were 1(4.76%) each. Pharmacokinetic versus pharmacodynamics interactions were 49(10.7%) versus 407(89.3%); 56(17.7%) versus 260(82.3%); and 8(12.5%) versus 56(87.5%) in loop, K-sparing and thiazide diuretics respectively with an overall Pharmacokinetic and pharmacodynamics interactions of 113(13.5%) versus 723(86.5%) respectively. A total of 19 potential outcomes resulting from 124 drug pairs, which accumulated to 1944 outcome cases were observed. Antagonism to potassium levels were the highest being 546 (28.1%). Others are increased risk of hyperkalemia 228(11.7%), risk of hypokalemia 16(0.8%), risk of hypotension 486(25.0%), risk of QT prolongation 2(0.1%), agents whose effects/levels is decreased by diuretic 120(6.2%), risk of SIADH 2(0.1), increase risk of adverse effects 88(4.5%) while risk of nephrotoxicity 26(1.3%), risk of decrease in the therapeutic effects/efficacy of diuretic 35(1.8%) and agents whose effects/therapeutic efficacy may be increased 190 (9.8%) may be potentially present. Combinations requiring monitoring K-levels accounted for 790 (41.3%). BP monitoring may be required in 486(25.4%) cases while downward and upward dosage adjustment of interacting drugs may be necessary in 289(15.1%) and 185(9.7%) cases respectively. Similarly diuretic upward and downward dosage modifications may be required in 36(1.9%) and 17(0.9%) cases respectively. Conclusion: Several potential drug interactions may be present in CHF Patients on diuretics with co-morbid diseases requiring medications. This calls for the need to keenly monitor all medications used by CHF patients as potentially lethal interactions may be present.

Keywords: Diuretic interactions, potassium sparing diuretic, loop diuretic, thiazide diuretic, Furosemide, Spironolactone, Congestive Heart Failure.