Triamterene with xipamide

Pharmacokinetic studies of triamterene in combination with other drugs have also been done. In human subjects pharmacokinetics of triamterene with xipamide, 8 with hydrochlorothiazide,69 with propranolol and hydrochlorothiazide combination,70 and with oxprenolol and hydrochlorothiazide combination,71 have been studied. Pharmacokinetic and pharmacodynamic studies of the combination of furosemide retard and triamterene have been done in detail in healthy volunteers.72-75 In another study triamterene is reported to reduce the extrarenal elimination of digoxin, but induced no changes in digoxin-elicited inotropy.76... 

A procedure for the determination of diuretics of different therapeutical character high (bumetanide, ethacrynic acid, furosemide), intermediate (bendroflumethiazide, chlorthalidone, hydrochlorothiazide, xipamide) and low (acetazolamide, amiloride, spironolactone, triamterene) efficacy diuretics, and the uricosuric agent probenecid, in urine samples, illustrates a method development implying the control of pH, surfactant and modifier [23]. The greatest analytical problems in the detection of these compounds are basically their wide variety of chemical structures, functional groups and protonation constants. This implies the use of several experimental conditions for their analysis with conventional aqueous-organic mobile phases and laborious liquid-liquid or solid-liquid extraction prior to chromatographic separation. In contrast, the same micellar eluent can produce a satisfactory separation after direct injection. 

Chromatograms of (a) urine matrix, (b) urine matrix spiked with a mixture of 1 pg/mL of each diuretic and (c) an aqueous solution of the diuretics, all eluted with a 0.042 M SDS-4% 1-propanol mobile phase in phosphate buffer at pH 4.5. Compounds (1) furosemide, (2) chlorthalidone, (3) ethacrynic acid, (4) bendroflumethiazide, (5) probenecid, (6) bumetanide, (7) amiloride, (8) xipamide, (9) spironolactone and (10) triamterene. Reprinted from Ref 23 with permission of Elsevier. 

Further optimization of mobile phase composition (SDS and 1-propanol concentration) was made using the method developed by Torres Lapasio et al. [40], assisted by ih MICHROM software (see attached CD ROM). Maximum resolution corresponded to 0.042 M SDS-4% 1-propanol. Fig. 11.8 shows the experimental chromatogram for this mobile phase of a urine sample spiked with a mixture of the diuretics, together with a similar chromatogram obtained with an aqueous solution. The retention times for both chromatograms were similar. The peaks of amiloride and xipamide, on the one hand and triamterene and spironolactone on the other, appeared mutually overlapped in the chromatograms. The peak of bendroflumethiazide was overlapped by the prominent peak of urine. 

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