Target site pharmacokinetics of doxycycline for rosacea in healthy volunteers is independent of the food effect

Pharmacokinetics of Antibacterial Agents in the Elderly: The Body of Evidence

Infections are important factors contributing to the morbidity and mortality among elderly patients. High rates of consumption of antimicrobial agents by the elderly may result in increased risk of toxic reactions, deteriorating functions of various organs and systems and leading to the prolongation of hospital stay, admission to the intensive care unit, disability, and lethal outcome. Both safety and efficacy of antibiotics are determined by the values of their plasma concentrations, widely affected by physiologic and pathologic age-related changes specific for the elderly population. Drug absorption, distribution, metabolism, and excretion are altered in different extents depending on functional and morphological changes in the cardiovascular system, gastrointestinal tract, liver, and kidneys. Water and fat content, skeletal muscle mass, nutritional status, use of concomitant drugs are other determinants of pharmacokinetics changes observed in the elderly. The choice of a proper dosing regimen is essential to provide effective and safe antibiotic therapy in terms of attainment of certain pharmacodynamic targets. The objective of this review is to perform a structure of evidence on the age-related changes contributing to the alteration of pharmacokinetic parameters in the elderly.

Alterations of human skin microbiome and expansion of antimicrobial resistance after systemic antibiotics

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Pharmacokinetics of panduratin A following oral administration of a Boesenbergia pandurata extract to rats

Boesenbergia pandurata and its major active ingredient, panduratin A (PAN), exhibit antibacterial, anti-oxidant, anti-inflammatory, and anti-obesity effects. We explored the time course of the plasma and tissue (in the major organs, gums and skin) concentrations of PAN after oral administration of a B. pandurata extract to rats. Model-dependent analysis was used to quantify the skin distribution of PAN after systemic exposure. The PAN level peaked at 1.12 ± 0.22 μg/mL after 3 h, and then biexponentially decayed with a terminal half-life of 9 h. The mean clearance (Cl/F) was 2.33 ± 0.68 L/h/kg. The PAN levels in organs were in the following order (highest first): skin, lung, heart, gum, liver, spleen, kidney, and brain. For the first time, the time course of PAN levels in plasma and organs was investigated after oral administration of a BPE. This study helps to explain the pharmacological activities of PAN in the skin and gums. The pharmacokinetic model provided data in the plasma and skin concentrations of PAN, which are of fundamental importance to evaluate its efficacy.

Tetracyclines improve experimental lymphatic filariasis pathology by disrupting interleukin-4 receptor-mediated lymphangiogenesis

Lymphatic filariasis is the major global cause of nonhereditary lymphedema. We demonstrate that the filarial nematode Brugia malayi induced lymphatic remodeling and impaired lymphatic drainage following parasitism of limb lymphatics in a mouse model. Lymphatic insufficiency was associated with elevated circulating lymphangiogenic mediators, including vascular endothelial growth factor C. Lymphatic insufficiency was dependent on type 2 adaptive immunity, the interleukin-4 receptor, and recruitment of C-C chemokine receptor-2–positive monocytes and alternatively activated macrophages with a prolymphangiogenic phenotype. Oral treatments with second-generation tetracyclines improved lymphatic function, while other classes of antibiotic had no significant effect. Second-generation tetracyclines directly targeted lymphatic endothelial cell proliferation and modified type 2 prolymphangiogenic macrophage development. Doxycycline treatment impeded monocyte recruitment, inhibited polarization of alternatively activated macrophages, and suppressed T cell adaptive immune responses following infection. Our results determine a mechanism of action for the antimorbidity effects of doxycycline in filariasis and support clinical evaluation of second-generation tetracyclines as affordable, safe therapeutics for lymphedemas of chronic inflammatory origin.

Cytotoxic and proapoptotic effect of doxycycline - An in vitro study on the human skin melanoma cells

Doxycycline is a semisynthetic, second generation tetracycline. Currently, it is used, among others, in the treatment of acne and skin infections. Moreover, doxycycline has many valuable nonantibiotic properties, including anti-inflammatory, immunosuppressive and anticancer effects. Recent studies showed that the drug had the ability to inhibit the adhesion and migration of cancer cells, as well as affected their growth and proliferation and induced apoptosis. The purpose of this study was to examine the antimelanoma effect of doxycycline. The obtained results demonstrated that doxycycline decreased the viability and inhibited the proliferation of human melanoma cells, proportionally to the drug concentration and the treatment time. It was stated that doxycycline disturbed the homeostasis of the cells by lowering intracellular level of reduced thiols. In addition, the treatment changed the cell cycle profile and triggered the DNA fragmentation. Mitochondria of melanoma cells exposed to the drug had lowered membrane potential, which indicated cells apoptosis. Finally, doxycycline induced the externalization phosphatidylserine - a well-known hallmark of apoptosis, confirmed by results of annexin V test. The presented study contributes to the increase of knowledge about nonantibacterial action of doxycycline, including the influence on human cancer cells and indicates new potential possibility of effective treatment of malignant melanoma.

A physiologically based pharmacokinetic model of doxycycline for predicting tissue residues and withdrawal intervals in grass carp (Ctenopharyngodon idella)

The extensive use of doxycycline in aquaculture results in drug residue violations that negatively impact human food safety. This study aimed to develop a physiologically based pharmacokinetic (PBPK) model for doxycycline to predict drug residues and withdrawal times (WTs) in grass carp (Ctenopharyngodon idella) after daily oral administration for 3 days. Physiological parameters including cardiac output and organ weights were measured experimentally. Chemical-specific parameters were obtained from the literature or estimated by fitting to the observed data. The model properly captured the observed kinetic profiles of doxycycline in tissues (i.e., liver, kidney, muscle + skin and gill). The predicted WT in muscle + skin by Monte Carlo analysis based on sensitive parameters identified at 24 h after drug administration was 41 d, which was similar to 43 d calculated using the tolerance limit method. Sensitivity analysis identified two additional sensitive parameters at 6 weeks: intestinal transit rate constant and urinary elimination rate constant. The predicted WT in muscle + skin based on sensitive parameters identified at 6 weeks was 54 d. This model provides a useful tool to estimate tissue residues and withdrawal times for doxycycline in grass carp and also serves a foundation for extrapolation to other fish species and other tetracyclines.

Target site pharmacokinetics of doxycycline for rosacea in healthy volunteers is independent of the food effect

Aims

Doxycycline (DFD‐09) oral capsules 40 mg are approved for the treatment of inflammatory lesions of rosacea. Unlike the food‐induced lowering of doxycycline's peak plasma concentration (C_max), its exposure under fed conditions in the skin, the drug's target site for rosacea, is unknown. The present study explored the effect of food on the dermal pharmacokinetics of doxycycline.

Methods

The pharmacokinetics of doxycycline in the dermal interstitial fluid (d‐ISF) and plasma of healthy volunteers were assessed in parallel groups under fed (n = 6) and fasting (n = 6) conditions during a 14‐day once‐daily treatment course with doxycycline oral capsules 40 mg (DFD‐09). Sampling of d‐ISF and plasma was performed on days 1, 10 (fasting group d‐ISF only) and 14.

Results

Twelve subjects were randomized, and 11 analysed. No causally drug‐related adverse events occurred. Dermal doxycycline exposures (C_max and area under the curve) under the fed state were about 30% lower than under the fasting state at day 1 but were similar at steady state. In analogy to skin, plasma exposure showed no between‐group difference at steady state. Accumulation ratios were higher in the skin than in plasma. Correcting for plasma protein binding (~90%), dermal doxycycline exposure was approximately threefold higher than unbound plasma exposure.

Conclusions

At steady state, doxycycline concentrations in the skin of fed and fasting healthy volunteers were comparable. Doxycycline's efficacy in rosacea is possibly due to considerable dermal accumulation of unbound doxycycline and is independent of the effect of food.