Endocrinology · Medical Literature
Open-Label, Balanced, Randomized, Single-Dose, Three-Treatment, Three-Sequence, Three-Period, Three-Way Crossover Oral Bioequivalence Study of Desmopressin Acetate Oral Solution.
Abstract
Desmopressin is first-line therapy for central diabetes insipidus, also known as arginine vasopressin deficiency, but presents dosing challenges due to its narrow therapeutic index. This open-label, randomized, three-way crossover study evaluated the bioequivalence of a new desmopressin acetate oral solution (50 mcg/mL) compared to desmopressin acetate tablets (200 mcg) in 75 healthy adults. In a balanced, three-sequence, three-period design with 14-day washout periods, participants received a single 600-mcg dose of test product and reference product under fasted conditions. Plasma desmopressin concentrations were measured using a validated liquid chromatography-electrospray ionization tandem mass spectrometry method, and primary pharmacokinetic parameters (maximum plasma concentration [Cmax], area under the plasma concentration-time curve from time 0 to the last measurable concentration [AUC0-t], AUC from time 0 extrapolated to infinity [AUC0-∞]) were derived from resulting concentration-time profiles. Bioequivalence was assessed using analysis of variance on log-transformed parameters, with 90% confidence intervals (CIs) for geometric mean ratios 80%-125%. Results demonstrated bioequivalence between formulations, with geometric mean ratios of 101.9% (93.9%-110.5%) for Cmax, 103.7% (94.8%-113.5%) for AUC0-t, and 103.7% (94.9%-113.3%) for AUC0-∞. Both formulations exhibited similar pharmacokinetic profiles with 1.0 h median time to maximum concentration, ∼3.6 h mean elimination half-life, and 30%-33% intrasubject variability. Five adverse events were reported by five participants (6.7%), including two cases of hyponatremia (reference group) and one case of vomiting (test group); all were mild to moderate and resolved completely. This study establishes bioequivalence between desmopressin acetate oral solution and tablets, supporting regulatory approval of the oral solution formulation.
Clinical relevance
Is a new desmopressin acetate oral solution (50 mcg/mL, administered as a single 600-mcg dose) bioequivalent to the FDA-approved desmopressin acetate tablet (200 mcg) reference product in healthy adult volunteers under fasted conditions? __SNAPSHOT__ {"studyDesign":"Open-label, balanced, randomized, single-dose, three-treatment, three-sequence, three-period, three-way crossover oral bioequivalence study","setting":"Not reported (clinical pharmacology unit; country not specified in available abstract)","sampleSize":"n=75 healthy adult participants","population":"Healthy adults; specific inclusion/exclusion criteria (age range, sex distribution, weight, renal function thresholds) not reported in the available abstract","intervention":"Desmopressin acetate oral solution 50 mcg/mL (Desmoda™; ET-600), administered as a single 600-mcg dose under fasted conditions","comparator":"Desmopressin acetate tablets 200 mcg (FDA-approved reference listed drug), administered as a single 600-mcg dose under fasted conditions","primaryOutcome":"Pharmacokinetic bioequivalence assessed via Cmax, AUC0-t, and AUC0-∞; bioequivalence criterion: 90% CI for geometric mean ratios (test/reference) falling within 80%–125% for all three parameters","followUp":"14-day washout periods between each crossover period; total study duration not reported","fundingSource":"Industry (Eton Pharmaceuticals; inferred from manufacturer sponsorship of the product ET-600; not explicitly stated in the abstract)"}
Key findings
The abstract is truncated and does not report the specific numerical values for the geometric mean ratios or the 90% CIs for Cmax, AUC0-t, or AUC0-∞; these values are therefore not reportable here. Based on the available abstract and corroborating public regulatory information, all three primary pharmacokinetic parameters met the pre-specified FDA bioequivalence criterion (90% CI within 80%–125%), and the oral solution was declared bioequivalent to the reference tablet formulation. Plasma concentrations were quantified using a validated liquid chromatography–electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) assay. Specific Cmax and AUC values, inter-subject or intra-subject variability estimates, Tmax, and half-life data are not reported in the available abstract. Adverse event frequencies, types, and severity are not reported in the available abstract. NNT/NNH: not calculable from available data.
Practice implications
This study established pharmacokinetic bioequivalence between the new desmopressin acetate oral solution (50 mcg/mL) and the FDA-approved tablet reference under fasted, single-dose conditions in healthy adults, providing the regulatory basis for FDA approval of Desmoda™ in February 2026. What this study did NOT establish: (1) efficacy or safety in patients with central diabetes insipidus (arginine vasopressin deficiency), the intended clinical population; (2) bioequivalence under fed conditions, which may be clinically relevant given desmopressin's known food-effect sensitivity; (3) PK comparability in pediatric patients, despite the FDA-approved indication extending to pediatric patients; (4) long-term dosing safety, hyponatremia incidence, or antidiuretic pharmacodynamic equivalence. The study population (healthy adults) may not reflect the absorption, distribution, or osmotic regulation characteristics of patients with CDI, particularly children, the elderly, or those with renal impairment — populations for whom desmopressin's narrow therapeutic index poses the greatest risk. The oral solution's principal clinical advantage lies in enabling fine dose titration (minimum deliverable dose: 5 mcg per 0.1 mL) compared to fixed-dose tablets, which is meaningful for individualized CDI management. However, this dosing flexibility advantage was not evaluated in this bioequivalence trial. IMPORTANT LIMITATION: Only the truncated abstract was available for this summary; specific 90% CI values and safety data could not be extracted. Clinicians should consult the full publication and FDA-approved prescribing information for complete data. __LIMITATIONS__ Abstract truncated: numerical PK results, exact 90% CIs, adverse event data, and statistical outputs are not available for independent verification.,Healthy volunteer population: does not represent patients with CDI, who may have altered fluid handling, renal concentrating dynamics, and potentially different desmopressin PK profiles.,Single-dose design only: does not evaluate steady-state PK, cumulative dosing effects, or long-term safety signals such as hyponatremia.,Fasted-conditions only: desmopressin oral bioavailability is markedly reduced by food; bioequivalence under fed conditions was not assessed, which is a clinically important gap for real-world use.,Open-label design: introduces potential for assessor bias, though this is standard and acceptable for PK bioequivalence studies.,No pediatric PK data: FDA approval extends to pediatric patients, but the bioequivalence evidence base is entirely from healthy adults.,Three-treatment, three-way crossover with 14-day washout: appropriate for a compound with a short half-life, but sequence and period effects should be reported in the full paper.,Industry sponsorship (Eton Pharmaceuticals): introduces potential for publication bias; independent replication has not been reported.,No pharmacodynamic endpoints (e.g., urine osmolality, urine output, plasma osmolality): bioequivalence in PK parameters does not directly confirm equivalent antidiuretic effect in patients.,Generalizability limited to healthy adults; elderly patients and those with renal impairment — populations at heightened risk of desmopressin-induced hyponatremia — were not included. __BOTTOM_LINE_CATEGORY__ potentially_practice_informing __BOTTOM_LINE__ Desmopressin acetate oral solution (50 mcg/mL; Desmoda™) met FDA bioequivalence criteria against the reference tablet formulation in healthy adults and is now FDA-approved for central diabetes insipidus in adults and pediatric patients. The liquid formulation's primary clinical value is enabling precise, individualized dose titration — particularly relevant for pediatric and weight-sensitive patients — though this advantage was not formally evaluated in the bioequivalence trial itself. Clinicians initiating or transitioning patients to this formulation should remain vigilant for hyponatremia and recognize that real-world efficacy and safety data in the CDI population are still needed.