There is considerable interest in the use of doxycycline post exposure prophylaxis (PEP) to reduce the incidence of bacterial sexually transmitted infections (STIs). An important concern is that this could select for tetracycline resistance in these STIs and other species. We searched PubMed and Google Scholar, (1948–2023) for randomized controlled trials comparing tetracycline PEP with non-tetracycline controls. The primary outcome was antimicrobial resistance (AMR) to tetracyclines in all bacterial species with available data. Our search yielded 140 studies, of which three met the inclusion criteria. Tetracycline PEP had no effect on the prevalence of tetracycline resistance in Neisseria gonorrhoeae in any of the three trials or the pooled estimates. PEP did, however, have a marked effect on the tetracycline MIC distribution in the one study where this was assessed. Prophylactic efficacy was 100% at low MICs and 0% at high MICs. In the one study where this was assessed, PEP resulted in a significant increase in tetracycline resistance in commensal Neisseria species compared to the control group but no significant effect on the prevalence of tetracycline resistance in Staphylococcus aureus. The available evidence suggests that PEP with tetracyclines could be associated with selecting tetracycline resistance in N. gonorrhoeae and commensal Neisseria species.

Regeneration of peripheral nerves depends on the ability of axons to navigate through an altered extracellular environment. It has been suggested that Schwann cells facilitate this process through their secretion of neuropeptides and proteases. Using the RT4-D6P2T Schwann cell line (RT4), we have previously shown that RT4 cultures endogenously express the neuropeptide PACAP, and respond to exogenous stimulation by inducing the expression of tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) through PAC1 receptor activation. In this study, based on recent findings showing that doxycycline and minocycline act as positive allosteric modulators (PAMs) of the PAC1 receptor, we tested if treatment with these tetracyclines could induce the expression and activity of tPA and uPA in RT4 cells. Using ELISA and zymographic analyses, we demonstrate that doxycycline and minocycline reliably induce the secretion and activity of both tPA and uPA, which is paralleled by an increased expression levels, as shown by immunocytochemistry and Western blots. These actions were mediated, at least in part, by the PAC1 receptor, as PACAP6-38 mitigated tetracycline-induced expression and activity of tPA and uPA. We conclude that doxycycline and minocycline can act as PAMs of the PAC1 receptor to promote proteolytic activity in RT4 cells.

Antibiotics are released into the environment either directly in an unchanged form or in a partially metabolized form. The discharge is usually through untreated waste or industrial treatment effluents. The potential concern is the uptake of these antibiotics by crops irrigated by treated wastewater. This study collected wastewater from eight points at the Pagla, Kadamtali, Dhaka treatment plant. Here we consider three crucial antibiotics, Doxycycline, Ciprofloxacin, and Tetracycline, used mainly during the last two years of the pandemic. A PDA detector was used in high-performance liquid chromatography (HPLC) analysis to determine the raw and processed effluent antibiotics. The most frequently seen antibiotics in natural wastewater were Doxycycline and Ciprofloxacin, with the highest concentration of 0.23µgL-1and 0.20 µgL-1(raw water), respectively. Tetracycline was not detected in natural water. Contrarily, Doxycycline was discovered in the Pagla plant's completed water and had the highest concentration (0.12 gL-1), whereas Ciprofloxacin and Tetracycline were not found in the dead water. The findings of this study showed that Doxycycline was still present in both the raw and processed effluent. Both natural and finished wastewater was subjected to a microbial-resistant test in the presence of all three antibiotics. The results revealed that the samples detected both heterotrophic bacteria and total coliform. The viable aerobic heterotrophic bacteria ranged between 5.421 and 4.754 log cfu/ml. Total bacteria load gradually decreased in the finished wastewater.

Most recent studies of doxycycline PEP have assessed doxycycline's effect on antimicrobial resistance by measuring the proportion of colonies of the target species with AMR as the outcome measure. In this study, we show that this method is insufficiently sensitive to detect shifts in MIC distribution.

Tetracyclines are a group of antibiotics whose first representative was discovered over 70 years ago. Since then, they have been of great interest in dermatology. In addition to their antibacterial activity, they are able to inhibit metalloproteinases and exhibit anti-inflammatory, anti-apoptotic and antioxidant effects. The side effects have been thoroughly studied over the years. The most characteristic and important in daily dermatolgical practice are: phototoxicity, hyperpigmentation, onycholysis, photoonycholysis, induced lupus erythematosus, idiopathic intracranial hypertension. In this article, we summarize the use of tetracyclines in infectious diseases and inflammatory dermatoses, and further discuss indications where the efficacy and safety of tetracyclines have been highlighted over the past few years.

Persistent post market quality evaluation helps produce clear information on the current quality status of the different brands of a given drug and hence introduces biopharmaceutically and therapeutically equivalent list of the products to the prescribers and users of it. This in turn facilitates access to essential medicines by breaking the high cost barrier imposed by few expensive brands of the product. This study was aimed at determining the quality and evaluating equivalence of doxycycline hyclate capsules and tablets in Jimma, Ethiopia. Ten brands of doxycycline hyclate capsules and tablets were tested for physic-chemical parameters. All investigated brands of doxycycline complied with the USP for dosage unifor¬mity, assay of active ingredient and single-point dissolution tests. One brand, D09 failed both hardness and friabilty tests. Comparisons of dissolution profiles applying fit factors confirmed that only brands D04, D06 and D07 had similarity with innovator. Ratio test approaches also showed significant variability existence between test products and comparators. This may question the product’s being categorized as a <biowaiver> to mean in-vitro dissolution evaluation suffices its market approval. This work, however, found equivalence problems between ‘comparators’ and interchangeability issues among doxycycline different brands already distributed in the market.

We are proposing, for any interested investigator, a randomized open clinical trial for mild and mild-to-moderate Covid-19 comparing a treatment regimen with standard of care, and eventually with another investigational regimen, if ongoing or will be implemented. The patients could be hospitalized or ambulatory but not requiring admission to intensive care units and mechanical ventilation. The proposed therapeutic regimen consists of doxycycline (an antimicrobial having also anti-inflammatory properties, probable antioxidant and possible some antiviral effects), and pentoxifylline, a hemorheological compound used in occlusive arterial diseases but also having proven anti-inflammatory properties. Doxycycline is included in the WHO’s list of essential medicine being an effective, safe, widely available, and inexpensive medication and widely accessible. It will be administered at a dosage of 100 mg orally twice daily for ten days. Pentoxifylline, in clinical use since 1972, and also widely accessible, will be given at a dosage of 400 mg orally, also twice daily, for ten days. The primary outcome measures are: 1) Progression of disease to a severe form requiring intensive care admission and mechanical ventilation; 2) Fatality rates and 3) Time to clinical recovery.This proposal was presented to the National Directors and Core Leads meeting of the Canadian Trials Network (CTN) on May 6, 2020. The interventional trial template suggested by CTN was used for designing the trial.

Inhibition of amyloid fibril formation could benefit patients with systemic amyloidosis. In this group of diseases, deposition of amyloid fibrils derived from normally soluble proteins leads to progressive tissue damage and organ failure. Although many small molecules have been proposed as inhibitors of amyloid formation, few have been successful in clinical trials. Amyloid formation is complex and several individual steps could be targeted by small molecules. However, the exact mechanism of action for a molecule is often not known, which impedes medicinal chemistry efforts to develop more potent molecules. Furthermore, commonly used assays are prone to artifacts that must be controlled for. Here, potential mechanisms by which small molecules could inhibit aggregation of immunoglobulin light chain dimers, the precursor proteins for AL amyloidosis are studied in assays that recapitulate different aspects of amyloidogenesis in vitro. One molecule reduced unfolding-coupled proteolysis of light chains, but no molecules inhibited aggregation of light chains or disrupted pre-formed amyloid fibrils. This work demonstrates the challenges associated with drug development for amyloidosis, but also highlights the potential to combine therapies that target different aspects of amyloidogenesis.