Taking Dyazide (hydrochlorothiazide and triamterene) while taking
amantadine reduced renal clearance of amantadine and induced adverse
effects including hallucinations (1, cited in 2).
Some medications increase orthostatic hypotension and are associated
with a higher rate of falling (3).
Wilson TW, Rajput AH.
Med Assoc J. 1983 Nov 1;129(9):974-5.
To document an interaction between amantadine hydrochloride and
Dyazide that had apparently produced amantadine toxicity, a patient
was given amantadine alone for 1 week, followed by amantadine plus
Dyazide for another week, under controlled conditions. A diuretic
effect was observed after Dyazide was added to the regimen, but the
urine amantadine excretion fell, and the drug's plasma concentration
increased. It was concluded that one or both of the components of
Dyazide (hydrochlorothiazide and triamterene) reduce the clearance
of amantadine and can produce higher plasma concentrations and toxic
disease between internal medicine and neurology.
Csoti I, Jost WH, Reichmann H.
J Neural Transm (Vienna). 2016
prevalence of orthostatic hypotension and its correlation with
potentially causative medications among elderly veterans.
Poon IO, Braun U.
J Clin Pharm Ther. 2005 Apr;30(2):173-8.
BACKGROUND: Orthostatic hypotension (OH) is defined as a reduction
of systolic blood pressure of at least 20 mmHg, or diastolic blood
pressure of at least 10 mmHg from a sitting to a standing
position. It is a common physical finding among older adults and
associated with significant morbidity and mortality. Use of
medications that have the potential to induce OH, particularly
concomitant use of several of such medications, is a major factor
for the development of OH....
RESULTS: A total of 505 individual patients attended the clinic
during the study period, and 342 patients fit the inclusion
criteria. About 189 of these patients (55%) had OH. Among patients
with OH, 61 patients (33%) were symptomatic, including 52 patients
who had falls. The prevalence of OH in patients receiving zero,
one, two, and three or more potentially causative medications was
35, 58, 60 and 65% respectively. Receiving hydrochlorothiazide was
associated with the highest prevalence of OH (65%), followed by
receiving lisinopril (60%), trazodone (58%), furosemide (56%) and