Vietnam Moves to Reassess a Familiar Acne Combination in Routine Practice
A new phase 4 study in Vietnam is set to examine adapalene/clindamycin phosphate gel as it is used in everyday dermatology practice, not in the controlled environment of a tightly scripted efficacy trial. The open-label, multicenter, single-arm design places the combination directly into routine care for Vietnamese patients aged 12 years and older with mild to moderate acne vulgaris. Investigators will follow safety, tolerability, and clinical response over 12 weeks, with visits at baseline and Weeks 2, 4, 8, and 12.
The trial is designed around a practical question dermatology clinics face constantly: how well does a topical retinoid-antibiotic combination perform when patients actually use it, with the skin-care habits, adherence patterns, and baseline irritation risks that come with real life? That matters because acne therapy is rarely judged by lesion counts alone. Facial redness, dryness, peeling, and itching can determine whether a patient stays on treatment long enough to benefit.
Why This Fixed-Dose Combination Still Draws Regulatory Attention
The study centers on Klenzit®-C, a fixed-dose gel containing adapalene 0.1% and clindamycin 1%. Adapalene acts through nuclear retinoic acid receptors to normalize follicular epithelial differentiation and reduce the microcomedone process that drives acne formation. Clindamycin suppresses bacterial protein synthesis and is bactericidal against C. acnes. Used together, the two agents address several points in acne pathogenesis at once: comedogenesis, inflammation, and the microbial contribution to inflammatory lesions.
A single sentence captures the rationale: the combination is meant to work faster and more broadly than either agent used alone.
Vietnamese regulators have asked for continued clinical data on the product’s safety and effectiveness, and the study operates under the Ministry of Health framework cited in the record. The product itself has been approved in Vietnam since 26 May 2008, and periodic safety review covering 2015 through 2024 did not identify new or significant safety signals. Reported events in those reviews were mostly application-site and skin reactions, with hypersensitivity events such as angioedema and swelling of the face or lips also described.
What the Study Will Measure at the Bedside
The cohort is expected to include about 225 participants, although the study overview also describes a planned population of about 360 patients at 3 to 5 sites. Participants will apply the gel once daily, preferably in the evening, for 12 weeks. The first application occurs in clinic at baseline, a detail that often matters in topical acne studies because early education can reduce misuse and improve consistency in the first days of treatment.
Investigators will record adverse events, serious adverse events, local tolerability, concomitant medications, lesion counts, investigator global assessment, and standardized clinical photography. Vital signs, height, weight, and body mass index are also tracked at visits. The primary emphasis is safety and tolerability, but the study also follows inflammatory and non-inflammatory lesion counts and the proportion of participants who reach treatment success on the Investigator Global Assessment at Weeks 4, 8, and 12.
Treatment success is defined as an IGA score of 0 or 1, paired with at least a 2-grade improvement from baseline. In acne medicine, that endpoint is clinically meaningful because a skin exam that shifts from moderate disease to clear or almost clear usually represents a visible change patients can recognize at home, not just in the chart.
Skin Irritation, Purging, and the Difference Between Response and Flare
The study pays close attention to local skin tolerability: erythema, dryness, hyperpigmentation, peeling, and pruritus are each graded on a 4-point scale. Those events often determine whether topical therapy succeeds in practice. Retinoids can be highly effective, but they can also trigger transient irritation during the first weeks of use, especially in patients who are new to topical therapy or who use harsh cleansers and layered actives.
The protocol also distinguishes acne purging from a true breakout. Purging is defined as a temporary rise in comedones of 30% or more with an inflammatory-lesion rise of 25% or less, typically occurring in Weeks 1 to 4 and resolving by about 8 weeks. A breakout, by contrast, reflects a rise in inflammatory lesions of more than 50%, possibly with nodules or spread into new areas. That separation is clinically useful because patients often stop treatment when they interpret an early inflammatory shift as failure, when the pattern may instead reflect a transient adjustment phase.
Eligibility Rules Shape the Real-World Signal
Enrollment is limited to patients with 10 to 50 inflammatory lesions and 5 to 50 non-inflammatory lesions, along with an IGA score of mild or moderate acne. Participants must also refrain from other topical acne therapies and from medicated cleansers, moisturizers, and skincare products containing active ingredients such as salicylic acid, benzoyl peroxide, azelaic acid, niacinamide, alpha hydroxy acids, or retinol. Gentle cleansers, moisturizers appropriate for the skin type, and sunscreen are allowed.
Pregnancy testing is required before enrollment for women of childbearing potential, and the trial withdraws participants if they become pregnant, use prohibited topical products, need a temporary dose reduction such as every-other-day application, or develop an intolerable adverse event. Serious adverse events and pregnancies are reported rapidly to the sponsor, and an interim safety review is planned at Week 2 after roughly half the participants have enrolled.
The structure creates a clean safety readout, but it also narrows the question. Because the trial is open-label and single-arm, it will not compare the gel against another topical regimen or against vehicle. Clinical interpretation will therefore depend on how lesion counts, tolerability, and investigator ratings move over time within this Vietnamese cohort, especially during the early weeks when irritation and purging can blur the line between expected pharmacology and poor tolerability.
Why This Trial Matters for Acne Care in Vietnam
For Vietnamese dermatology services, the study may help clarify whether a long-used fixed-dose topical combination continues to balance efficacy and tolerability in routine care across multiple sites. The biologic logic is straightforward: adapalene reduces microcomedone formation and inflammation, while clindamycin suppresses the bacterial component of inflammatory acne. The clinical question is less simple, because topical treatment success depends on adherence, skin sensitivity, and the willingness to push through the first few weeks of irritation.
The trial begins on 25 February 2026, with primary completion estimated for 28 February 2027 and final completion for 10 May 2027. What remains unresolved is not whether the combination has a sound mechanistic basis, but how consistently that benefit appears in real-world Vietnamese patients when safety, irritation, and early discontinuation are tracked closely over 12 weeks.