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Photoreactions with a fluoroquinolone antimicrobial: evening versus morning dosing
N J Lowe1, T D Fakouhi, R S Stern
1Skin Research Foundation, Santa Monica.
Abstract:
Quinolone antimicrobials absorb ultraviolet radiation and, with appropriate drug concentrations, may cause photoreactions. Photoreactions have been reported for several quinolones, including lomefloxacin, a difluorinated quinolone antimicrobial. This study was designed to determine whether the interval between administration of lomefloxacin and exposure to ultraviolet A (UVA) light would affect skin responses. The minimal erythema dose (MED) and severity of local reactions were the main parameters of evaluation. Exposure to UVA radiation 2 hours after morning dosing caused an increase in skin sensitivity as assessed by changes in MED (p < 0.05). No changes were observed with exposure 16 hours after evening dosing (p = 1.00). Edema and blisters at the radiation sites were observed in only the morning dosing group. A significant negative correlation was observed between lomefloxacin plasma concentrations and change MEDs (r = -0.72; p < 0.05). An evening dosing strategy may minimize the risk of phototoxic effects.
Insights
Taking lomefloxacin in the morning increases skin sensitivity to ultraviolet A (UVA) light, potentially causing phototoxic reactions. Evening dosing may reduce these risks by minimizing drug concentrations during sun exposure.
Area of Science:
- Pharmacology
- Dermatology
- Photobiology
Background:
- Quinolone antimicrobials, like lomefloxacin, can cause phototoxic reactions due to ultraviolet radiation absorption.
- Photoreactions are a known side effect of certain quinolone antimicrobials.
Purpose of the Study:
- To investigate if the timing of lomefloxacin administration relative to ultraviolet A (UVA) light exposure influences skin responses.
- To evaluate the impact of dosing interval on phototoxicity severity and minimal erythema dose (MED).
Main Methods:
- Participants received morning or evening doses of lomefloxacin.
- Skin sensitivity was assessed by measuring the minimal erythema dose (MED) after UVA radiation exposure at different time intervals.
- Local skin reactions, including edema and blisters, were documented.
Main Results:
- UVA exposure 2 hours after morning lomefloxacin dosing significantly increased skin sensitivity (decreased MED, p < 0.05).
- No significant changes in skin sensitivity were observed with UVA exposure 16 hours after evening dosing (p = 1.00).
- Edema and blisters occurred only in the morning dosing group; a negative correlation existed between lomefloxacin plasma levels and MED changes (r = -0.72, p < 0.05).
Conclusions:
- The interval between lomefloxacin administration and UVA light exposure is critical in determining phototoxic risk.
- An evening dosing schedule for lomefloxacin appears to minimize the risk of phototoxic skin reactions compared to morning dosing.