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Published on: November 24, 2021
In vitro comparison of the dermal penetration of three different topical formulations containing lasalocid
Evie C Knight1, Darren J Trott2, Stephen W Page3
1Dermatology for Animals, 263 Appleby Road, Stafford, Queensland, 4053, Australia.
Background:
Topical antimicrobial preparations are of utmost importance in treating suspected and confirmed meticillin-resistant Staphylococcus pseudintermedius (MRSP) infections due to the increasing incidence of widespread resistance to systemic antimicrobials. Lasalocid is active against MRSP in vitro and this may become an important topical antimicrobial for the treatment of canine pyoderma.
Hypothesis/Objectives:
To determine effects of various formulation types on penetration and retention of lasalocid applied to canine skin in vitro.
Animals:
Normal canine skin was collected from the thorax of five dogs that had been euthanized on the basis of health and/or intractable behavioural issues.
Methods:
Solution, lotion and ointment containing 2% lasalocid were applied to ex vivo canine skin. Transdermal penetration was assessed for a 24 h period and retention of lasalocid was assessed at the conclusion of the study.
Results:
The solution had significantly higher skin retention of lasalocid and proportion of applied dose retained in skin than lotion and ointment (Tukey-Kramer Honest Significant Difference test, P < 0.01). Lasalocid could not be detected in the receptor fluid of any Franz cell at any time point.
Conclusions And Clinical Importance:
Lasalocid was not identified in the receptor fluid of any sample, indicating that systemic absorption of the active ingredient in vivo is unlikely. Lasalocid may be useful in the treatment of MRSP infections if in vivo studies support safety and efficacy.
Insights
Topical lasalocid showed higher skin retention in a solution formulation compared to lotions or ointments. Systemic absorption is unlikely, suggesting potential for treating canine pyoderma caused by MRSP.
Area of Science:
- Veterinary Dermatology
- Antimicrobial Research
- Pharmacokinetics
Background:
- Topical antimicrobials are crucial for treating meticillin-resistant Staphylococcus pseudintermedius (MRSP) due to rising systemic resistance.
- Lasalocid demonstrates in vitro activity against MRSP, presenting a potential topical treatment for canine pyoderma.
Purpose of the Study:
- To evaluate how different topical formulations affect lasalocid penetration and retention in canine skin.
- To assess the potential for systemic absorption of lasalocid when applied topically to canine skin.
Main Methods:
- Ex vivo canine skin samples were treated with 2% lasalocid solutions, lotions, and ointments.
- Transdermal penetration and skin retention of lasalocid were measured over a 24-hour period using Franz cells.
Main Results:
- The solution formulation resulted in significantly higher lasalocid retention in the skin compared to lotion and ointment formulations (P < 0.01).
- Lasalocid was undetectable in the receptor fluid across all formulations and time points, indicating no transdermal passage.
Conclusions:
- Topical lasalocid is unlikely to be systemically absorbed in dogs, based on the absence in receptor fluid.
- Lasalocid shows promise as a topical antimicrobial for canine pyoderma, pending further in vivo safety and efficacy studies.
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