Minocycline attenuates mechanical allodynia and proinflammatory cytokine expression in rat models of pain facilitation

Activated glial cells (microglia and astroglia) in the spinal cord play a major role in mediating enhanced pain states by releasing proinflammatory cytokines and other substances thought to facilitate pain transmission. In the present study, we report that intrathecal administration of minocycline, a selective inhibitor of microglial cell activation, inhibits low threshold mechanical allodynia, as measured by the von Frey test, in two models of pain facilitation. In a rat model of neuropathic pain induced by sciatic nerve inflammation (sciatic inflammatory neuropathy, SIN), minocycline delayed the induction of allodynia in both acute and persistent paradigms. Moreover, minocycline was able to attenuate established SIN-induced allodynia 1 day, but not 1 week later, suggesting a limited role of microglial activation in more perseverative pain states. Our data are consistent with a crucial role for microglial cells in initiating, rather than maintaining, enhanced pain responses. In a model of spinal immune activation by intrathecal HIV-1 gp120, we show that the anti-allodynic effects of minocycline are associated with decreased microglial activation, attenuated mRNA expression of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-1beta-converting enzyme, TNF-alpha-converting enzyme, IL-1 receptor antagonist and IL-10 in lumbar dorsal spinal cord, and reduced IL-1beta and TNF-alpha levels in the CSF. In contrast, no significant effects of minocycline were observed on gp120-induced IL-6 and cyclooxygenase-2 expression in spinal cord or CSF IL-6 levels. Taken together these data highlight the importance of microglial activation in the development of exaggerated pain states.

A comparison of two antimicrobial-impregnated central venous catheters. Catheter Study Group

BACKGROUND

The use of central venous catheters impregnated with either minocycline and rifampin or chlorhexidine and silver sulfadiazine reduces the rates of catheter colonization and catheter-related bloodstream infection as compared with the use of unimpregnated catheters. We compared the rates of catheter colonization and catheter-related bloodstream infection associated with these two kinds of antiinfective catheters.

METHODS

We conducted a prospective, randomized clinical trial in 12 university-affiliated hospitals. High-risk adult patients in whom central venous catheters were expected to remain in place for three or more days were randomly assigned to undergo insertion of polyurethane, triple-lumen catheters impregnated with either minocycline and rifampin (on both the luminal and external surfaces) or chlorhexidine and silver sulfadiazine (on only the external surface). After their removal, the tips and subcutaneous segments of the catheters were cultured by both the roll-plate and the sonication methods. Peripheral-blood cultures were obtained if clinically indicated.

RESULTS

Of 865 catheters inserted, 738 (85 percent) produced culture results that could be evaluated. The clinical characteristics of the patients and the risk factors for infection were similar in the two groups. Catheters impregnated with minocycline and rifampin were 1/3 as likely to be colonized as catheters impregnated with chlorhexidine and silver sulfadiazine (28 of 356 catheters [7.9 percent] vs. 87 of 382 [22.8 percent], P<0.001), and catheter-related bloodstream infection was 1/12 as likely in catheters impregnated with minocycline and rifampin (1 of 356 [0.3 percent], vs. 13 of 382 [3.4 percent] for those impregnated with chlorhexidine and silver sulfadiazine; P<0.002).

CONCLUSIONS

The use of central venous catheters impregnated with minocycline and rifampin is associated with a lower rate of infection than the use of catheters impregnated with chlorhexidine and silver sulfadiazine.

Minocycline treatment in acute stroke: an open-label, evaluator-blinded study

BACKGROUND

Ischemic animal model studies have shown a neuroprotective effect of minocycline.

OBJECTIVE

To analyze the effect of minocycline treatment in human acute ischemic stroke.

METHODS

We performed an open-label, evaluator-blinded study. Minocycline at a dosage of 200 mg was administered orally for 5 days. The therapeutic window of time was 6 to 24 hours after onset of stroke. Data from NIH Stroke Scale (NIHSS), modified Rankin Scale (mRS), and Barthel Index (BI) were evaluated. The primary objective was to compare changes from baseline to day 90 in NIHSS in the minocycline group vs placebo.

RESULTS

One hundred fifty-two patients were included in the study. Seventy-four patients received minocycline treatment, and 77 received placebo. NIHSS and mRS were significantly lower and BI scores were significantly higher in minocycline-treated patients. This pattern was already apparent on day 7 and day 30 of follow-up. Deaths, myocardial infarctions, recurrent strokes, and hemorrhagic transformations during follow-up did not differ by treatment group.

CONCLUSIONS

Patients with acute stroke had significantly better outcome with minocycline treatment compared with placebo. The findings suggest a potential benefit of minocycline in acute ischemic stroke.

Targeting leukocyte MMPs and transmigration: minocycline as a potential therapy for multiple sclerosis

Multiple sclerosis is characterized by the infiltration of leukocytes into the CNS. As matrix metalloproteinases (MMPs) facilitate the passage of leukocytes across matrix barriers, we tested the hypothesis that targeting MMPs could attenuate neuro-inflammation. We report that minocycline, a widely used generic drug with a good safety record, inhibited MMP activity, reduced production of MMP-9 and decreased the transmigration of T lymphocytes across a fibronectin matrix barrier. In addition, minocycline was efficacious against both mild and severe experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of multiple sclerosis. When severe EAE was produced, minocycline pre-treatment delayed the course of the disease: when maximal disease activity occurred in vehicle-treated EAE mice, minocycline animals were relatively normal and had minimal signs of inflammation and demyelination in the CNS. When tested in mice afflicted with mild EAE, minocycline attenuated the clinical severity of disease throughout the course of treatment. These results indicate that minocycline may constitute a safe and inexpensive therapy for multiple sclerosis.

Intracerebral hemorrhage induces macrophage activation and matrix metalloproteinases

Intracerebral hemorrhage (ICH) is characterized by parenchymal hematoma formation with surrounding inflammation. Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of neurological diseases defined by inflammation and cell death. To investigate the expression profile and pathogenic aspects of MMPs in ICH, we examined MMP expression in vivo using a collagenase-induced rat model of ICH. ICH increased brain MMP-2, -3, -7, and -9 mRNA levels relative to sham-injected (control) animals in the vicinity of the hematoma, but MMP-12 (macrophage metalloelastase) was the most highly induced MMP (>80-fold). Immunohistochemistry showed MMP-12 to be localized in activated monocytoid cells surrounding the hematoma. In vitro studies showed that thrombin, released during ICH, induced MMP-12 expression in monocytoid cells, which was reduced by minocycline application. Similarly, in vivo minocycline treatment significantly reduced MMP-12 levels in brain. Neuropathological studies disclosed marked glial activation and apoptosis after ICH that was reduced by minocycline treatment. Neurobehavioral outcomes also were improved with minocycline treatment compared with untreated ICH controls. Thus, select MMPs exhibit increased expression after ICH, whereas minocycline is neuroprotective after ICH by suppressing monocytoid cell activation and downregulating MMP-12 expression.

Pharmacokinetics of tigecycline after single and multiple doses in healthy subjects

Tigecycline, a novel glycylcycline antibiotic, exhibits strong activity against gram-positive, gram-negative, aerobic, anaerobic, and atypical bacterial species, including many resistant pathogens, i.e., vancomycin-resistant enterococci, methicillin-resistant Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae. The safety and tolerability of tigecycline administered as single or multiple doses or at various infusion rates were explored in three phase 1, randomized, double-blind, placebo-controlled studies in healthy subjects. Full pharmacokinetic profiles of tigecycline were determined in two of these studies. Subjects in the single-dose study received 12.5 to 300 mg of tigecycline, which differed with respect to the duration of infusion, subjects' feeding status, and ondansetron pretreatment. Subjects in the ascending multiple-dose study received 25 to 100-mg doses of tigecycline as a 1-h infusion every 12 h. The variable volume and infusion rate study consisted of administration of 100-mg loading dose of tigecycline, followed by 50 mg every 12 h for 5 days. Serum samples were analyzed for tigecycline by validated high-pressure liquid chromatography or liquid chromatography/tandem mass spectrometry methods. Systemic clearance ranged from 0.2 to 0.3 liters/h/kg, and the tigecycline half-life ranged from 37 to 67 h. Tigecycline had a large volume of distribution (7 to 10 liters/kg), indicating extensive distribution into the tissues. Food increased the maximum tolerated single-dose from 100 to 200 mg, but the duration of infusion did not affect tolerability. Side effects, mainly nausea and vomiting, which are common to the tetracycline class of antimicrobial agents, were seen in these studies. Tigecycline exhibits linear pharmacokinetics and is safe and well tolerated in the dose ranges examined.

Short-term effects of intensive periodontal therapy on serum inflammatory markers and cholesterol

Severe periodontitis has been associated with increased systemic inflammation. In a three-arm preliminary randomized trial, we investigated the impact of standard (SPT) and intensive periodontal therapy (IPT) on serum inflammatory markers and cholesterol levels. Medical and periodontal parameters, C-reactive protein (CRP), interleukin-6 (IL-6), total cholesterol, and LDL cholesterol were evaluated in 65 systemically healthy subjects suffering from severe generalized periodontitis. Two months after treatment, both SPT and IPT resulted in significant reductions in serum CRP compared with the untreated control (0.5 +/- 0.2 mg/L for SPT, P = 0.030 and 0.8 +/- 0.2 mg/L for IPT, P = 0.001). Similar results were observed for IL-6. Changes in inflammation were independent of age, gender, body mass index, and ethnicity, but a significant interaction between cigarette smoking and treatment regimen was found. The IPT group also showed a decrease in total and LDL cholesterol after 2 months. Analysis of these data indicates that periodontitis causes moderate systemic inflammation in systemically healthy subjects.

Antibacterial Envelope to Prevent Cardiac Implantable Device Infection

BACKGROUND

Infections after placement of cardiac implantable electronic devices (CIEDs) are associated with substantial morbidity and mortality. There is limited evidence on prophylactic strategies, other than the use of preoperative antibiotics, to prevent such infections.

METHODS

We conducted a randomized, controlled clinical trial to assess the safety and efficacy of an absorbable, antibiotic-eluting envelope in reducing the incidence of infection associated with CIED implantations. Patients who were undergoing a CIED pocket revision, generator replacement, or system upgrade or an initial implantation of a cardiac resynchronization therapy defibrillator were randomly assigned, in a 1:1 ratio, to receive the envelope or not. Standard-of-care strategies to prevent infection were used in all patients. The primary end point was infection resulting in system extraction or revision, long-term antibiotic therapy with infection recurrence, or death, within 12 months after the CIED implantation procedure. The secondary end point for safety was procedure-related or system-related complications within 12 months.

RESULTS

A total of 6983 patients underwent randomization: 3495 to the envelope group and 3488 to the control group. The primary end point occurred in 25 patients in the envelope group and 42 patients in the control group (12-month Kaplan-Meier estimated event rate, 0.7% and 1.2%, respectively; hazard ratio, 0.60; 95% confidence interval [CI], 0.36 to 0.98; P = 0.04). The safety end point occurred in 201 patients in the envelope group and 236 patients in the control group (12-month Kaplan-Meier estimated event rate, 6.0% and 6.9%, respectively; hazard ratio, 0.87; 95% CI, 0.72 to 1.06; P<0.001 for noninferiority). The mean (±SD) duration of follow-up was 20.7±8.5 months. Major CIED-related infections through the entire follow-up period occurred in 32 patients in the envelope group and 51 patients in the control group (hazard ratio, 0.63; 95% CI, 0.40 to 0.98).

CONCLUSIONS

Adjunctive use of an antibacterial envelope resulted in a significantly lower incidence of major CIED infections than standard-of-care infection-prevention strategies alone, without a higher incidence of complications. (Funded by Medtronic; WRAP-IT ClinicalTrials.gov number, NCT02277990.).

Serum, tissue and body fluid concentrations of tigecycline after a single 100 mg dose

OBJECTIVES

The purpose of this study was to determine the tissue and corresponding serum concentration of tigecycline at selected time points in gall bladder, bile, colon, bone, synovial fluid (SF), lung and CSF in subjects undergoing surgical or medical procedures.

METHODS

One hundred and four adult subjects (aged 24-83 years; 64 women, 40 men) received a single intravenous (i.v.) dose of tigecycline (100 mg infused over 30 min). Subjects were randomly assigned to one of four collection times at 4, 8, 12 and 24 h after the start of the infusion. For CSF, samples were collected at approximately 1.5 and 24 h after the start of the infusion. All subjects had serum samples collected before the administration of tigecycline, at the end of the infusion and at the time corresponding to tissue or body fluid collection. Drug concentrations in serum, tissues and body fluids were determined by LC/MS/MS. The area under the mean concentration-time curve from 0 to 24 h (AUC(0-24)) was determined for the comparison of systemic exposure between tissue or body fluid to serum.

RESULTS

The mean serum concentrations of tigecycline were similar to those previously published. Tissue penetration, expressed as the ratio of AUC(0-24) in tissue or body fluid to serum, was 537 for bile, 23 for gall bladder, 2.6 for colon, 2.0 for lung, 0.41 for bone, 0.31 for SF and 0.11 for CSF.

CONCLUSIONS

A single 100 mg dose of intravenous tigecycline produced considerably higher tissue/fluid concentrations in bile, gall bladder, colon and lung compared with simultaneous serum concentrations. On average, the systemic exposure of tigecycline in bone, SF and CSF ranged from 11% to 41% of serum concentrations. The results in bone are inconsistent with previous radiolabelled studies in animals and it is unclear if tight binding to bone (versus low bone uptake) or poor extraction of tigecycline for LC/MS/MS detection or both may have contributed to the differences we observed in humans.

Minocycline markedly protects the neonatal brain against hypoxic-ischemic injury

Hypoxic-ischemic brain injury in the perinatal period is a major cause of morbidity and mortality. Presently, there are no proven effective therapies with which to safeguard the human neonatal brain against this type of injury. Minocycline, a semisynthetic tetracycline, has been shown to be neuroprotective in certain adult ischemic injury/stroke and neurodegenerative disease models. However, minocycline's neuroprotective effects have not been assessed after insults to the neonatal brain. We now report that minocycline administered either immediately before or immediately after a hypoxic-ischemic insult substantially blocks tissue damage in a rodent model of neonatal hypoxic-ischemic brain injury. Minocycline treatment prevents the formation of activated caspase-3, a known effector of apoptosis, as well as the appearance of a calpain cleaved substrate, a marker of excitotoxic/necrotic cell death. To our knowledge, this is the first report of a systemic treatment that can be administered after a hypoxic-ischemic insult, which provides robust, nearly complete neuroprotection to the developing brain. Our data suggest that minocycline or a related neuroprotective tetracycline may be a candidate to consider in human clinical trials to protect the developing brain against hypoxic-ischemic-induced damage.

Excess deaths associated with tigecycline after approval based on noninferiority trials

BACKGROUND

On the basis of noninferiority trials, tigecycline received Food and Drug Administration (FDA) approval in 2005. In 2010, the FDA warned in a safety communication that tigecycline was associated with an increased risk of death.

METHODS

PubMed, EMBASE, Scopus, and ClinicalTrials.gov were searched using the terms "tigecycline" and "randomized controlled trial (RCT)" through April 2011. Excess deaths and noncure rates for both approved and nonapproved indications were examined using meta-analysis.

RESULTS

Ten published and 3 unpublished studies met inclusion criteria (N = 7434). No significant heterogeneity was seen for mortality (I(2 )= 0%; P = .99) or noncure rates (I(2 )= 25%; P = .19). Across randomized controlled trials, tigecycline was associated with increased mortality (risk difference [RD], 0.7%; 95% confidence interval [CI], 0.1%-1.2%; P = .01) and noncure rates (RD, 2.9%; 95% CI, 0.6%-5.2%; P = .01). Effects were not isolated to type of infection or comparator antibiotic regimen, and the impact on survival remained significant when limited to trials of approved indications (I(2 )= 0%; RD, 0.6%; P = .04). A pooled analysis of the 5 trials completed by early 2005 before tigecycline was approved would have demonstrated a similar harmful effect of tigecycline on survival (I(2 )= 0%; RD, 0.7%; P = .06).

CONCLUSIONS

Pooling noninferiority studies to examine survival may help ensure the safety and efficacy of new antibiotics. The association of tigecycline with excess deaths and noncure includes indications for which it is approved and marketed. Tigecycline cannot be relied on in serious infections.

Efficacy of antimicrobial-impregnated external ventricular drain catheters: a prospective, randomized, controlled trial

OBJECT

Catheter-related infection of the cerebrospinal fluid (CSF) pathways is a potentially life-threatening complication of external ventricular drainage. A major source of infection is bacterial contamination along the external ventricular drain (EVD) catheter track. The authors examined the efficacy of EVD catheters impregnated with minocycline and rifampin in preventing these catheter-related infections.

METHODS

The authors conducted a prospective, randomized clinical trial at six academic medical centers. All hospitalized patients 18 years or older who required placement of an EVD catheter were eligible for inclusion in the study. Patients were randomly assigned to undergo placement of an EVD with a catheter impregnated with minocycline and rifampin or a standard untreated catheter (control group). To assess primary outcome, CSF samples were collected using a sterile technique at the time of catheter insertion, at least every 72 hours while the catheter remained in place, and at the time of catheter removal. At the time of removal, CSF cultures were obtained from the tip and tunneled segments of each catheter by performing semiquantitative roll-plate and quantitative sonication techniques. Of the 306 patients enrolled in the study, data from 288 were included in the final analysis. Eighteen patients were excluded from analysis: 14 because the ventricular catheter was in place less than 24 hours, and four because CSF cultures obtained at the time of catheter insertion were positive for infection. Of these 288 patients, 139 were assigned to the control group and 149 to the treatment group. The two groups were well matched with respect to all clinical characteristics, including patient sex and mean age, indication for catheter placement, and length of time the catheter remained in place. The antibiotic-impregnated catheters were one half as likely to become colonized as the control catheters (17.9 compared with 36.7%, respectively, p < 0.0012). Positive CSF cultures were seven times less frequent in patients with antibiotic-impregnated catheters compared with those in the control group (1.3 compared with 9.4%, respectively, p = 0.002).

CONCLUSIONS

The use of EVD catheters impregnated with minocycline and rifampin can significantly reduce the risk of catheter-related infections.

Reduction of opioid withdrawal and potentiation of acute opioid analgesia by systemic AV411 (ibudilast)

Morphine-induced glial proinflammatory responses have been documented to contribute to tolerance to opioid analgesia. Here, we examined whether drugs previously shown to suppress glial proinflammatory responses can alter other clinically relevant opioid effects; namely, withdrawal or acute analgesia. AV411 (ibudilast) and minocycline, drugs with distinct mechanisms of action that result in attenuation of glial proinflammatory responses, each reduced naloxone-precipitated withdrawal. Analysis of brain nuclei associated with opioid withdrawal revealed that morphine altered expression of glial activation markers, cytokines, chemokines, and a neurotrophic factor. AV411 attenuated many of these morphine-induced effects. AV411 also protected against spontaneous withdrawal-induced hyperactivity and weight loss recorded across a 12-day timecourse. Notably, in the spontaneous withdrawal study, AV411 treatment was delayed relative to the start of the morphine regimen so to also test whether AV411 could still be effective in the face of established morphine dependence, which it was. AV411 did not simply attenuate all opioid effects, as co-administering AV411 with morphine or oxycodone caused three-to-five-fold increases in acute analgesic potency, as revealed by leftward shifts in the analgesic dose response curves. Timecourse analyses revealed that plasma morphine levels were not altered by AV411, suggestive that potentiated analgesia was not simply due to prolongation of morphine exposure or increased plasma concentrations. These data support and extend similar potentiation of acute opioid analgesia by minocycline, again providing converging lines of evidence of glial involvement. Hence, suppression of glial proinflammatory responses can significantly reduce opioid withdrawal, while improving analgesia.

Intrathecal minocycline attenuates peripheral inflammation-induced hyperalgesia by inhibiting p38 MAPK in spinal microglia

Activation of p38 mitogen-activated protein kinase (p38) in spinal microglia is implicated in spinal nociceptive processing. Minocycline, a tetracycline derivative, displays selective inhibition of microglial activation, a function that is distinct from its antibiotic activity. In the present study we examined antinociceptive effects of intrathecal (IT) administration of minocycline in experimental models of inflammation-evoked hyperalgesia in addition to the effect of minocycline on stimulation-induced activation of p38 in spinal microglia. Intrathecal minocycline produced a dose-dependent reduction of formalin-evoked second-phase flinching behaviour in rats, and prevented thermal hyperalgesia induced by carrageenan injection into the paw. In contrast, systemic delivery (intraperitoneally) of minocycline inhibited the first but not the second phase of formalin-induced flinching, and it had no effect on carrageenan-induced hyperalgesia. Centrally mediated hyperalgesia induced by IT delivery of N-methyl-d-aspartate was completely blocked by IT minocycline. An increase in phosphorylation (activation) of p38 (P-p38) was observed in the dorsal spinal cord after carrageenan paw injection, assessed by both Western blotting and immunohistochemistry. The increased P-p38 immunoreactivity was seen primarily in microglia but also in a small population of neurons. Minocycline, at the IT dose that blocked carrageenan-induced hyperalgesia, also attenuated the increased P-p38 in microglia. In addition, minocycline suppressed lipopolysaccharide-evoked P-p38 in cultured spinal microglial cells. Taken together, these findings show that minocycline given IT produces a potent and consistent antinociception in models of tissue injury and inflammation-evoked pain, and they provide strong support for the idea that this effect is mediated by direct inhibition of spinal microglia and subsequent activation of p38 in these cells.

Minocycline to improve neurologic outcome in stroke (MINOS): a dose-finding study

BACKGROUND AND PURPOSE

Minocycline is a promising anti-inflammatory and protease inhibitor that is effective in multiple preclinical stroke models. We conducted an early phase trial of intravenous minocycline in acute ischemic stroke.

METHODS

Following an open-label, dose-escalation design, minocycline was administered intravenously within 6 hours of stroke symptom onset in preset dose tiers of 3, 4.5, 6, or 10 mg/kg daily over 72 hours. Minocycline concentrations for pharmacokinetic analysis were measured in a subset of patients. Subjects were followed for 90 days.

RESULTS

Sixty patients were enrolled, 41 at the highest dose tier of 10 mg/kg. Overall age (65±13.7 years), race (83% white), and sex (47% female) were consistent across the doses. The mean baseline National Institutes of Health Stroke Scale score was 8.5±5.8 and 60% received tissue plasminogen activator. Minocycline infusion was well tolerated with only 1 dose limiting toxicity at the 10-mg/kg dose. No severe hemorrhages occurred in tissue plasminogen activator-treated patients. Pharmacokinetic analysis (n=22) revealed a half-life of approximately 24 hours and linearity of parameters over doses.

CONCLUSIONS

Minocycline is safe and well tolerated up to doses of 10 mg/kg intravenously alone and in combination with tissue plasminogen activator. The half-life of minocycline is approximately 24 hours, allowing every 24-hour dosing. Minocycline may be an ideal agent to use with tissue plasminogen activator.

The effect of antimicrobial periodontal treatment on circulating tumor necrosis factor-alpha and glycated hemoglobin level in patients with type 2 diabetes

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) may play an important role in insulin resistance. In this study, we hypothesized that TNF-alpha produced due to periodontal inflammation synergistically affects insulin resistance as well as TNF-alpha produced from adipose tissues in insulin-resistant type 2 diabetes patients. Therefore, to understand the effects of antimicrobial periodontal therapy on serum TNF-alpha concentration and subsequent metabolic control of diabetes, we examined the periodontal and diabetic status on 13 type-2 diabetes patients.

METHODS

These patients were treated with local minocycline administration in every periodontal pocket around all existing teeth once a week for a month. Before and after treatment, the number of total bacteria in the periodontal pockets and circulating TNF-alpha concentration were measured and the HbA1c value was assessed.

RESULTS

Antimicrobial therapy significantly reduced the number of microorganisms in periodontal pockets (P <0.01). After treatment, the circulating TNF-alpha level was significantly reduced (P <0.015). The HbA1c value was also reduced significantly (P <0.007). In addition, the 6 patients who were not receiving insulin therapy demonstrated decreased fasting insulin levels (P <0.03), and HOMA-R (P <0.03) indices. The average reductions in circulating TNF-alpha concentration and HbA1c value were 0.49 pg/ml and 0.8%, respectively.

CONCLUSION

The results indicate that anti-infectious treatment is effective in improving metabolic control in diabetics, possibly through reduced serum TNF-alpha and improved insulin resistance.

The role of local drug delivery in the management of periodontal diseases: a comprehensive review

This review article evaluates the role of local drug delivery systems in the management of periodontal diseases. The efficacy of several local delivery devices (i.e., tetracycline fibers, metronidazole and minocycline gels, chlorhexidine chips, and doxycycline polymer) which are either commercially available in the United States or abroad, or are currently under consideration for Food and Drug Administration (FDA) approval are discussed. The drug delivery systems are assessed with regard to their functional characteristics, effectiveness as a monotherapy, as compared to scaling and root planing, and ability to enhance conventional therapy. Furthermore, controversies associated with local delivery are addressed (e.g., induction of bacterial resistant strains, the efficacy of systemic versus local drug delivery, and whether local drug delivery should function as an alternative or as an adjunct to conventional treatment).

Delayed minocycline inhibits ischemia-activated matrix metalloproteinases 2 and 9 after experimental stroke

Background

Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) are increased in the brain after experimental ischemic stroke in rats. These two proteases are involved with the degradation of the basal lamina and loss of stability of the blood brain barrier that occurs after ischemia and that is associated with thrombolytic therapy in ischemic stroke. Minocycline is a lipophilic tetracycline and is neuroprotective in several models of brain injury. Minocycline inhibits inflammation, apoptosis and extracellular matrix degradation. In this study we investigated whether delayed minocycline inhibits brain MMPs activated by ischemia in a model of temporary occlusion in Wistar rats.

Results

Both MMP-2 and MMP-9 were elevated in the ischemic tissue as compared to the contra-lateral hemisphere after 3 hours occlusion and 21 hours survival (p < 0.0001 for MMP-9). Intraperitoneal minocycline at 45 mg/kg concentration twice a day (first dose immediately after the onset of reperfusion) significantly reduced gelatinolytic activity of ischemia-elevated MMP-2 and MMP-9 (p < 0.0003). Treatment also reduced protein concentration of both enzymes (p < 0.038 for MMP-9 and p < 0.018 for MMP-2). In vitro incubation of minocycline in concentrations as low as 0.1 μg/ml with recombinant MMP-2 and MMP-9 impaired enzymatic activity and MMP-9 was more sensitive at lower minocycline concentrations (p < 0.05).

Conclusion

Minocycline inhibits enzymatic activity of gelatin proteases activated by ischemia after experimental stroke and is likely to be selective for MMP-9 at low doses. Minocycline is a potential new therapeutic agent to acute treatment of ischemic stroke.

Treatment of periodontitis by local administration of minocycline microspheres: a controlled trial

BACKGROUND

Periodontitis is an inflammatory condition of tooth-supporting tissues that is usually treated by mechanical removal of plaque and microorganisms that adhere to teeth. This treatment, known as scaling and root planing, is not optimally effective. Adjunctive therapy with locally delivered antimicrobials has resulted in improved clinical outcomes such as probing depth reduction. This article reports on the efficacy and safety of locally administered microencapsulated minocycline.

METHODS

Seven hundred forty-eight (748) patients with moderate to advanced periodontitis were enrolled in a multi-center trial and randomized to 1 of 3 treatment arms: 1) scaling and root planing (SRP) alone; 2) SRP plus vehicle; or 3) SRP plus minocycline microspheres. The primary outcome measure was probing depth reduction at 9 months. Clinical assessments were performed at baseline and 1, 3, 6, and 9 months.

RESULTS

Minocycline microspheres plus scaling and root planing provided substantially more probing depth reduction than either SRP alone or SRP plus vehicle. The difference reached statistical significance after the first month and was maintained throughout the trial. The improved outcome was observed to be independent of patients' smoking status, age, gender, or baseline disease level. There was no difference in the incidence of adverse effects among treatment groups.

CONCLUSIONS

Scaling and root planing plus minocycline microspheres is more effective than scaling and root planing alone in reducing probing depths in periodontitis patients.

Long-term silicone central venous catheters impregnated with minocycline and rifampin decrease rates of catheter-related bloodstream infection in cancer patients: a prospective randomized clinical trial

PURPOSE

To evaluate the efficacy of long-term nontunneled silicone catheters impregnated with minocycline and rifampin (M-R) in reducing catheter-related bloodstream infections.

PATIENTS AND METHODS

This prospective, randomized, double-blind clinical trial was conducted at M.D. Anderson Cancer Center, a tertiary care hospital in Houston, TX. All patients in the trial had a malignancy.

RESULTS

Between September 1999 and May 2002, 356 assessable catheters were used: 182 M-R and 174 nonimpregnated. The patients' characteristics were comparable between the two study groups. The mean (+/- standard deviation) duration of catheterization with M-R catheters was comparable to that of nonimpregnated catheters (66.21 +/- 30.88 v 63.01 +/- 30.80 days). A total of 17 catheter-related bloodstream infections occurred during the course of the study. Three were associated with the use of M-R catheters and 14 were associated with the nonimpregnated catheters, with a rate of catheter-related bloodstream infection of 0.25 and 1.28/1,000 catheter-days, respectively (P = .003). Gram-positive cocci accounted for the majority of the organisms causing the infections. There were no allergic reactions associated with M-R catheters.

CONCLUSION

Long-term nontunneled central venous catheters impregnated with minocycline and rifampin are efficacious and safe in reducing catheter-related bloodstream infections in cancer patients.

Impact of local adjuncts to scaling and root planing in periodontal disease therapy: a systematic review

BACKGROUND

Chronic periodontitis affects many adults in the United States, some severely enough to threaten tooth loss. Of particular clinical importance is whether scaling and root planing (SRP) accompanied by a local adjunctive therapeutic agent improves outcomes over time compared to SRP alone. The adjunctive therapeutic agents investigated include: tetracycline, minocycline, metronidazole, a group of other antibiotics, chlorhexidine, and a group of antimicrobials. Primary outcomes considered are reductions in probing depth (PD) and gains in clinical attachment level (CAL).

METHODS

RTI-UNC Evidence-Based Practice Center staff searched MEDLINE (1966 through December 2002) and EMBASE (through February 2002) to identify clinical trials published in English that 1) involved adults with chronic periodontitis but no serious comorbidities; 2) tested one or more chemical antimicrobial agents as an adjunct to SRP alone or with a placebo; 3) had a concurrent control group that received the same SRP as the treatment group; 4) reported outcomes for specified, fixed time periods; and 5) if multiple antimicrobials were tested, reported outcomes for each agent separately. We performed qualitative analyses and meta-analyses of PD and CAL effect sizes when the necessary data were available from at least three studies at 6-month follow-up.

RESULTS

Among the locally administered adjunctive antimicrobials, the most positive results occurred for tetracycline, minocycline, metronidazole, and chlorhexidine. Adjunctive local therapy generally reduced PD levels. Differences between treatment and SRP-only groups in the baseline-to-follow-up period typically favored treatment groups but usually only modestly (e.g., from about 0.1 mm to nearly 0.5 mm) even when the differences were statistically significant. Effects for CAL gains were smaller and statistical significance less common. The marginal improvements in PD and CAL were a fraction of the improvement from SRP alone.

CONCLUSIONS

Whether such improvements, even if statistically significant, are clinically meaningful remains a question. A substantial agenda of future research to address this and other issues (e.g., costs, patient-oriented outcomes) is suggested.

Local anti-infective therapy: pharmacological agents. A systematic review

BACKGROUND

It is well recognized that periodontal diseases are bacterial in nature. An essential component of therapy is to eliminate or control these pathogens. This has been traditionally accomplished through mechanical means (scaling and root planing [SRP]), which is time-consuming, difficult, and sometimes ineffective. Over the past 20 years, locally delivered, anti-infective pharmacological agents, most recently employing sustained-release vehicles, have been introduced to achieve this goal.

RATIONALE

This systematic review evaluates literature-based evidence in an effort to determine the efficacy of currently available anti-infective agents, with and without concurrent SRP, in controlling chronic periodontitis.

FOCUSED QUESTION

In patients with chronic periodontitis, what is the effect of local controlled-release anti-infective drug therapy with or without SRP compared to SRP alone on changes in clinical, patient-centered, and adverse outcomes?

SEARCH PROTOCOL

MEDLINE, the Cochrane Central Trials Register, and Web of Science were searched. Hand searches were performed of the Journal of Clinical Periodontology, Journal of Periodontology, and Journal of Periodontal Research. Searches were performed for articles published through April 2002. In addition, investigators contacted editors of the above-mentioned journals and companies sponsoring research on these agents for related unpublished data and studies in progress.

SELECTION CRITERIA

INCLUSION CRITERIA

Studies included randomized controlled clinical trials (RCT), and case-controlled and cohort studies at least 3 months long. Therapeutic interventions had to include 1) SRP alone; 2) local anti-infective drug therapy and SRP; or 3) local anti-infective drug therapy alone. Included studies had to report patient-based mean values and measures of variation for probing depth (PD) and/or clinical attachment levels (CAL) for both test and control groups.

EXCLUSION CRITERIA

Studies were excluded if they: 1) included data from a previously published article; 2) included daily rinsing with chlorhexidine (CHX); or 3) had unclear descriptions of randomization procedures, examiner masking, or concomitant therapies.

DATA COLLECTION AND ANALYSIS

For the meta-analysis, PD and CAL were expressed as summary mean effects with 95% confidence intervals (CI) for the effect, and analyzed using a standardized difference between SRP alone and experimental agent groups. The results were assessed with both fixed-effects and random-effects models. Studies were ranked according to the York system.

MAIN RESULTS

1. Thirty-two studies were included (28 RCT, 2 cohort, and 2 case-control), incorporating a total patient population of 3,705 subjects. 2. Essentially all studies reported substantial reductions in gingival inflammation and bleeding indices, which were similar in both control and experimental groups. 3. A meta-analysis completed on 19 studies that included SRP and local sustained-release agents compared with SRP alone indicated significant adjunctive PD reduction or CAL gain for minocycline (MINO) gel, microencapsulated MINO, CHX chip and doxycycline (DOXY) gel during SRP compared to SRP alone. 4. Use of antimicrobial irrigants or anti-infective sustained-release systems as an adjunct to SRP does not result in significant patient-centered adverse events.

REVIEWERS' CONCLUSIONS

1. In some populations, anti-infective agents in a sustained-release vehicle alone can reduce PD and bleeding on probing (BOP) equivalent to that achieved by SRP alone. 2. No evidence was found for an adjunctive effect on reduction of PD and BOP of therapist-delivered CHX irrigation during SRP compared to SRP alone. 3. Additional RCTs are needed which evaluate the effectiveness of these therapies in all forms of periodontitis. 4. The study protocol for future RCTs should include appropriate statistical analyses and complete data sets to facilitate future evidence-based reviews. 5. Alternative surrogate parameters to PD and CAL need to be identified and validated such as microbial, inflammatory, or tissue-destructive markers that could be used in conjunction with clinical parameters to help determine the patient's response to emerging technologies that target the infectious and/or inflammatory aspects of periodontitis. 6. Future Phase IV clinical trials should be designed that evaluate local anti-infective therapies in conjunction with SRP in a manner consistent with current standards of care and evaluate cost-effectiveness. 7. The use of local anti-infective agents in at-risk patient populations and for the treatment of at-risk disease sites needs to be validated in randomized controlled clinical trials. 8. Several local anti-infective agents combined with SRP appear to provide additional benefits in PD reduction and CAL gain compared to SRP alone. The decision to use local anti-infective adjunctive therapy remains a matter of individual clinical judgment, the phase of treatment, and the patient's status and preferences.

Propionibacterium acnes resistance to antibiotics in acne patients

The minimal inhibitory concentration (MIC) of Propionibacterium acnes in seventy-five acne patients receiving long-term antibiotic therapy demonstrated the emergence of resistant strains. The mean MIC in thirty-three patients receiving long-term tetracycline was four to five times higher than that found in control groups of acne patients not receiving antibiotic therapy and controls free of acne. The average MIC for erythromycin was more than 100 times higher in those receiving long-term antibiotic therapy. In a second group of sixty-two patients, the clinical course and number of P. acnes were correlated with the presence of "resistant strains" defined as P. acnes with a tenfold increase in MIC to tetracycline or erythromycin. Patients with resistant strains had higher counts of P. acnes and clinically were not doing as well as those with sensitive strains.

Steady-state serum and intrapulmonary pharmacokinetics and pharmacodynamics of tigecycline

The steady-state serum and intrapulmonary pharmacokinetic and pharmacodynamic parameters of tigecycline were determined after intravenous administration in 30 subjects. Tigecycline was administered as a 100mg loading dose followed by six 50mg doses given every 12h and was measured using HPLC/mass spectrometry. Ratios of tigecycline maximum serum concentration and area under the serum concentration-time curve to 90%-minimum inhibitory concentrations (C(max)/MIC(90); AUC/MIC(90)), and percentage time above MIC(90) were calculated for common respiratory pathogens (Streptococcus pneumoniae, Chlamydia pneumoniae, Mycoplasma pneumoniae, Moraxella catarrhalis and Haemophilus influenzae). The C(max) (mean+/-S.D.), AUC and half-life for serum were 0.72+/-0.24 microg/mL, 1.73+/-0.64 microg*h/mL and 15.0+/-1.10h; for lung epithelial lining fluid (ELF) the values were 0.37 microg/mL, 2.28 microg*h/mL and 39.1h; and for alveolar cells (AC) were 15.2 microg/mL, 134 microg*h/mL and 23.7h. Tigecycline was concentrated in AC: C(max)/MIC(90) ratios ranged from 30.4 (H. influenzae) to 507 (S. pneumoniae); AUC/MIC(90) ratios ranged from 268 (H. influenzae) to 4467 (S. pneumoniae); and percentage dose interval above MIC(90) was 100% for the five respiratory pathogens. The C(max)/MIC(90), AUC/MIC(90) ratios, T>MIC(90) and extended serum and intrapulmonary half-lives following the regimen used in this study are favourable for the treatment of tigecycline-susceptible pulmonary infections.

Selective nanovector mediated treatment of activated proinflammatory microglia/macrophages in spinal cord injury

Much evidence shows that acute and chronic inflammation in spinal cord injury (SCI), characterized by immune cell infiltration and release of inflammatory mediators, is implicated in development of the secondary injury phase that occurs after spinal cord trauma and in the worsening of damage. Activation of microglia/macrophages and the associated inflammatory response appears to be a self-propelling mechanism that leads to progressive neurodegeneration and development of persisting pain state. Recent advances in polymer science have provided a huge amount of innovations leading to increased interest for polymeric nanoparticles (NPs) as drug delivery tools to treat SCI. In this study, we tested and evaluated in vitro and in vivo a new drug delivery nanocarrier: minocycline loaded in NPs composed by a polymer based on poly-ε-caprolactone and polyethylene glycol. These NPs are able to selectively target and modulate, specifically, the activated proinflammatory microglia/macrophages in subacute progression of the secondary injury in SCI mouse model. After minocycline-NPs treatment, we demonstrate a reduced activation and proliferation of microglia/macrophages around the lesion site and a reduction of cells with round shape phagocytic-like phenotype in favor of a more arborized resting-like phenotype with low CD68 staining. Treatment here proposed limits, up to 15 days tested, the proinflammatory stimulus associated with microglia/macrophage activation. This was demonstrated by reduced expression of proinflammatory cytokine IL-6 and persistent reduced expression of CD68 in traumatized site. The nanocarrier drug delivery tool developed here shows potential advantages over the conventionally administered anti-inflammatory therapy, maximizing therapeutic efficiency and reducing side effects.