Antimicrobial safety: focus on fluoroquinolones

BACKGROUND/PURPOSE

Infrequent toxicities associated with certain drugs and drug classes have recently gained much attention from different health-care perspectives. To protect the patient, continued surveillance of safety and tolerability data is essential. Data from preclinical testing, phase 1-3 trials, and postmarketing surveillance may be used to objectively assess the risks associated with a specific drug or family of compounds. This review summarizes safety and tolerability data for the quinolones.

MAIN FINDINGS

The most common adverse events associated with the quinolone class involve the gastrointestinal tract (nausea and diarrhea) and central nervous system (CNS) (headache and dizziness). These adverse events are usually mild and do not require discontinuation of therapy. Uncommon and potentially serious quinolone-related adverse events involve the cardiovascular system (rate-corrected electrocardiographic QT interval prolongation), musculoskeletal system (tendinitis and tendon rupture), endocrine system (glucose homeostasis dysregulation), renal system (crystalluria, interstitial nephritis, and acute renal failure), and the CNS (seizures). Severe idiosyncratic adverse events are specific to individual agents that may share some structural congruity, such as the 1-(2,4)-difluorophenyl group shared by trovafloxacin (associated with hepatitis), temafloxacin (associated with hemolytic-uremic syndrome), and tosufloxacin (associated with eosinophilic pneumonitis). Overall, discontinuation rates from clinical trials were <4% for the currently marketed quinolones. Quinolones with higher discontinuation rates, such as trovafloxacin (7.0%) and grepafloxacin (6.4%), are no longer available for general use.

CONCLUSIONS

The currently marketed quinolones are well tolerated, with safety profiles similar to those of other antimicrobial classes. Although adverse effects are unusual, some, including tendinitis and CNS-related effects, are more common with quinolones than with other antimicrobial classes. Rare adverse effects attributed to some members of the quinolone family (e.g., Torsades de Pointes, hepatotoxicity, and dysglycemias) are more likely to occur in select "susceptible" populations. These adverse events can often be circumvented by avoiding exposure to the specific quinolone. In some cases, the therapeutic value offered by a quinolone may outweigh its potential risks.

Fluoroquinolone-associated tendinopathy: a critical review of the literature

With the expanded use of fluoroquinolones for the treatment of community-acquired respiratory infections and reports of tendon injury linked to the use of these agents, we reviewed the literature to investigate the frequency and strength of this association. Ninety-eight case reports were available for review. The incidence of tendon injury associated with fluoroquinolone use is low in a healthy population but increases in patients who have renal dysfunction, who are undergoing hemodialysis, or who have received renal transplants. Pefloxacin and ciprofloxacin were most frequently implicated, but tendon injury was reported with most fluoroquinolones. The median duration of fluoroquinolone treatment before the onset of tendon injury was 8 days, although symptoms occurred as early as 2 hours after the first dose and as late as 6 months after treatment was stopped. Up to one-half of patients experienced tendon rupture, and almost one-third received long-term corticosteroid therapy. Tendon injury associated with fluoroquinolone use is significant, and risk factors such as renal disease or concurrent corticosteroid use must be considered when these agents are prescribed.

Etiologic factors associated with symptomatic achilles tendinopathy

BACKGROUND

The purpose of this study was to determine if a statistical association exists between Achilles tendinopathy (also referred to as tendinosis) and obesity, diabetes mellitus, hypertension, the supplemental use of estrogen, and exposure to local or systemic steroids.

METHODS

From July, 1997, to February, 2003, 82 patients with a diagnosis of Achilles tendinopathy were identified. The diagnosis of Achilles tendinopathy was confirmed by a review of medical records, radiographs, and MRI. There were 44 women and 38 men with an average age of 50 (range 27 to 77) years. For the parameters of obesity, hypertension, diabetes, steroid exposure, and the use of estrogen compounds, all patients were analyzed both cumulatively and stratified into subgroups by gender and age. Chi-square 2 x 2 tables were used to compare the observed prevalence of the parameters in patients with Achilles tendinopathy to the expected prevalence of these disorders and exposures in the population at large.

RESULTS

Cumulatively, 98% percent (43 of 44 women; 29 of 38 men) had hypertension, diabetes, obesity, and steroid or estrogen exposure. Seventy-six percent of men (29) had hypertension, diabetes, and obesity, or steroid exposure. Sixty-eight percent of women (15 of 22) had a history of hormone replacement therapy and 44% (8 of 15) had a positive history for use of oral contraceptives. When compared with published national data using Chi-square analysis, the association between tendinopathy and hormone replacement therapy and oral contraceptives was found to be statistically significant with p-values of 0.01 and 0.001, respectively. For both women and men, obesity was statistically associated with Achilles tendinopathy with p-values of 0.025 and. 001, respectively. Hypertension was statistically associated with Achilles tendinopathy only for women. Diabetes mellitus and Achilles tendinopathy were found to have a statistical association only for men younger than 44 years old

CONCLUSIONS

Obesity, hypertension, and steroids have as their end-organ effect a diminution of local microvascularity. The significant correlation of these factors with Achilles tendinopathy suggests the importance of their effect on microvascularity in the development of Achilles tendinopathy.

Insulin-like growth factor-I improves cellular and molecular aspects of healing in a collagenase-induced model of flexor tendinitis

Flexor tendinitis is a common and debilitating injury of elite and recreational athletes. Healing may be improved through intratendinous injection of insulin-like growth factor-I (IGF-I), which has been shown in vitro to stimulate mitogenesis and enhance tendon matrix production. This study investigated the effects of intratendinous injection of IGF-I on tendon healing in an equine model of flexor tendinitis. Collagenase-induced lesions were created in the tensile region of theflexor digitorum superficialis tendon of both forelimbs of eight horses. Treated tendons were injected with 2 microg rhlGF-I intralesionally every other day for 10 injections, while controls received 0.9% NaCl. Tendon fiber deposition and organization were evaluated serially using ultrasonography throughout the 8 week trial period. Following euthanasia, the tendons were harvested and DNA, hydroxyproline, and glycosaminoglycan content determined, mechanical strength and stiffness evaluated, gene expression and spatial arrangement of collagen types I and III assessed by northern blot and in situ hybridization, and tendon fiber architecture assessed by polarized light microscopy. Local soft tissue swelling was reduced in the IGF-I treated limbs. Similarly, lesion size in IGF-I treated tendons was smaller 3 and 4 weeks after initiation of treatment. Cell proliferation and collagen content of the IGF-I treated tendons were increased compared to controls. Mechanically, IGF-I treated tendons showed a trend toward increased stiffness compared to saline treated controls. Considered together with the decreased soft tissue swelling and improved sonographic healing, these data support the potential use of intralesional IGF-I for treatment of debilitating tendon injuries.

Extracorporeal shock waves promote healing of collagenase-induced Achilles tendinitis and increase TGF-beta1 and IGF-I expression

Extracorporeal shock waves (ESW) have recently been used in resolving tendinitis. However, mechanisms by which ESW promote tendon repair is not fully understood. In this study, we reported that an optimal ESW treatment promoted healing of Achilles tendintis by inducing TGF-beta1 and IGF-I. Rats with the collagenease-induced Achilles tendinitis were given a single ESW treatment (0.16 mJ/mm(2) energy flux density) with 0, 200, 500 and 1000 impulses. Achilles tendons were subjected to biomechanical (load to failure and stiffness), biochemical properties (DNA, glycosaminoglycan and hydroxyproline content) and histological assessment. ESW with 200 impulses restored biomechanical and biochemical characteristics of healing tendons 12 weeks after treatment. However, ESW treatments with 500 and 1000 impulses elicited inhibitory effects on tendinitis repair. Histological observation demonstrated that ESW treatment resolved edema, swelling, and inflammatory cell infiltration in injured tendons. Lesion site underwent intensive tenocyte proliferation, neovascularization and progressive tendon tissue regeneration. Tenocytes at the hypertrophied cellular tissue and newly developed tendon tissue expressed strong proliferating cell nuclear antigen (PCNA) after ESW treatment, suggesting that physical ESW could increase the mitogenic responses of tendons. Moreover, the proliferation of tenocytes adjunct to hypertrophied cell aggregate and newly formed tendon tissue coincided with intensive TGF-beta1 and IGF-I expression. Increasing TGF-beta1 expression was noted in the early stage of tendon repair, and elevated IGF-I expression was persisted throughout the healing period. Together, low-energy shock wave effectively promoted tendon healing. TGF-beta1 and IGF-I played important roles in mediating ESW-stimulated cell proliferation and tissue regeneration of tendon.

Safety Concerns with Fluoroquinolones

OBJECTIVE

To review the chemistry, pharmacology, and safety of fluoroquinolones.

DATA SOURCES

A MEDLINE search (1966-July 2007) was conducted using the key words fluoroquinolones or quinolones with safety, adverse effects, hypoglycemia, hyperglycemia, dysglycemia, QTc prolongation, torsades, seizures, phototoxicity, tendon rupture, Clostridium difficile, and pseudomembranous colitis for articles published in the English language.

STUDY SELECTION AND DATA EXTRACTION

Medicinal chemistry, in vitro, animal, and human trials were reviewed for information on the chemistry, pharmacology, and safety of each fluoroquinolone. Clinical trials were reviewed and included to compare the safety of systemic fluoroquinolones on the market. Literature on the pathology of serious adverse effects was also reviewed.

DATA SYNTHESIS

Gatifloxacin has been shown to increase the risk of hospitalization for dysglycemia in patients with and without diabetes. Hyperglycemia may occur with any fluoroquinolone, especially if not properly dose adjusted. Hypoglycemia may occur with any fluoroquinolone and has a higher frequency in patients receiving concomitant oral hypoglycemic drugs or insulin. Use of any fluoroquinolone should be avoided in patients with risk factors for QTc interval prolongation or tendinopathy. All fluoroquinolones should be used with caution in patients with a history of seizure disorders and may cause phototoxicity or C. difficile-associated diarrhea (CDAD).

CONCLUSIONS

Clinicians should be aware of possible alterations in blood glucose, QTc interval prolongation, seizures, phototoxicity, tendinopathy, or CDAD with the use of any fluoroquinolone, especially in patients with other risk factors for these conditions. Clinicians should closely monitor for these adverse effects and appropriately adjust doses to minimize these risks. To provide safe treatment for patients needing antibiotic therapy, an assessment of the risk-benefit ratio may be warranted in the decision to use a fluoroquinolone.

Tendon disorders attributed to fluoroquinolones: a study on 42 spontaneous reports in the period 1988 to 1998

OBJECTIVE

Fluoroquinolone antibiotics have been associated with tendinitis and tendon rupture. In this paper we report on the followup of 42 spontaneous reports of fluoroquinolone-associated tendon disorders.

METHODS

This study is based on cases of fluoroquinolone-associated tendon disorders reported to the Netherlands Pharmacovigilance Foundation Lareb and the Drug Safety Unit of the Inspectorate for Health Care between January 1, 1988, and January 1, 1998. By means of a mailed questionnaire, we collected information on the site of injury, onset of symptoms, treatment, and course of the tendon disorder as well as information on possible risk factors and concomitant medication.

RESULTS

Of 50 mailed questionnaires, 42 (84%) were returned. The data concerned 32 patients (76%) with tendinitis and 10 patients (24%) with a tendon rupture. Sixteen cases (38%) were attributed to ofloxacin, 13 (31%) to ciprofloxacin, 8 (19%) to norfloxacin, and 5 (12%) to pefloxacin. There was a male predominance, and the median age of the patients was 68 years. Most of the reports concerned the Achilles tendon, and 24 patients (57%) had bilateral tendinitis. The latency period between the start of treatment and the appearance of the first symptoms ranged from 1 to 510 days with a median of 6 days. Most patients recovered within 2 months after cessation of therapy, but 26% had not yet recovered at followup.

CONCLUSION

These reports suggest that fluoroquinolone-associated tendon disorders are more common in patients over 60 years of age. Ofloxacin was implicated most frequently relative to the number of filled prescriptions in the Netherlands.

Rat tendon morphologic and functional changes resulting from soft tissue mobilization

Augmented Soft Tissue Mobilization (ASTM) is a new non-invasive soft tissue mobilization technique which has been used successfully to treat a variety of musculoskeletal disorders. The purpose of this study was to determine the effects of ASTM therapy on the morphological and functional characteristics of enzyme induced injured rat Achilles tendons. Four groups of five rats were allocated as follows: (A) control, (B) tendinitis, (C) tendinitis plus ASTM, and (D) ASTM alone. Collagenase injury was induced, and the surgical site was allowed to heal for 3 wk. ASTM was performed on the Achilles tendon of groups C and D for 3 min on postoperative days 21, 25, 29, and 33 for a total of four treatments. Gait data were gathered prior to each treatment. The Achilles tendons of each group were harvested 1 wk after the last treatment. Specimens were prepared for light and electron microscopy, and immunostaining for type I and type III collagen and fibronectin was performed. Light microscopy showed increased fibroblast proliferation in the tendinitis plus ASTM treatment group. Although healing in rats may not translate directly to healing in humans, the findings of this study suggest that ASTM may promote healing via increased fibroblast recruitment.

Comparison of side effects of levofloxacin versus other fluoroquinolones

The side-effect profile of levofloxacin was compared with that of other fluoroquinolones based on European and international data from approximately 130 million prescriptions. Levofloxacin was found to be very safe with a low rate of hepatic abnormalities (1/650,000). In contrast, 140 trovafloxacin-treated patients developed hepatic problems, 14 of which were severe, and 8 required transplantation. The main CNS problems associated with fluoroquinolones include dizziness, convulsions, psychosis, and insomnia. Levofloxacin, ofloxacin, and moxifloxacin reportedly have the lowest potential of inducing central nervous system (CNS) adverse events among the fluoroquinolones currently available. Cardiovascular problems were seen in 1/15 million levofloxacin prescriptions compared to 1-3% of sparfloxacin patients having QTc prolongation of greater than 500 msec. Moxifloxacin was also associated with QTc prolongation when compared to non-fluoroquinolone comparators. Nausea, vomiting, and diarrhoea remain the main adverse drug reactions (ADRs) associated with levofloxacin. However, the ADR rate for levofloxacin is still one of the lowest of any fluoroquinolone at 2% (compared to 2-10% for other fluoroquinolones). Ofloxacin and levofloxacin have a very low phototoxic potential, whereas this is a problem for sparfloxacin, enoxacin, and pefloxacin. The tolerance profile of levofloxacin can be considered to be very good, and better than most, if not all of the fluoroquinolones available.

Evidence of tendinitis provoked by fluoroquinolone treatment: a case-control study

OBJECTIVE

To investigate the association between the use of fluoroquinolone agents and the risk of tendinitis in a large population-based case-control study.

METHODS

The study was performed by linking automated health databases from the Region of Lombardia, Italy. Cases were patients aged > or =18 years who had a hospital discharge diagnosis of non-traumatic tendinitis in 2002-3. For each case, up to five controls were randomly selected among those eligible for inclusion in the study. A conditional logistic regression model was used to estimate the odds ratio of tendinitis associated with the current, recent and past use of fluoroquinolones. Odds ratios were adjusted for exposure to other antibacterials and other drugs.

RESULTS

22,194 cases and 104,906 controls met the inclusion criteria. Current use of fluoroquinolones significantly increased the risk of tendon disorders as a whole (odds ratio [OR] = 1.7; 95% CI 1.4, 2.0), tendon rupture (OR = 1.3; 95% CI 1.0, 1.8) and rupture of the Achilles' tendon (OR = 4.1; 95% CI 1.8, 9.6). Concomitant use of corticosteroids and fluoroquinolones increased the risk of both tendon rupture (OR = 3.1; 95% CI 1.5, 6.3) and rupture of the Achilles' tendon (OR = 43.2; 95% CI 5.5, 341.1).

DISCUSSION

Evidence that exposure to fluoroquinolones is associated with the sudden occurrence of tendinitis is supported by this large population-based study. We can estimate that a single case of rupture of the Achilles' tendon would occur for every 5958 persons treated with fluoroquinolones (95% CI 2148, 23,085). The corresponding number needed to harm is 979 (95% CI 122, 9172) for patients who concomitantly use corticosteroids and 1638 (95% CI 351, 8843) for those aged >60 years.

CONCLUSION

Clinicians should be aware of this adverse effect, and the increased risk for fluoroquinolone-associated tendinitis in elderly patients with corticosteroid use must be considered when these agents are prescribed.

Chronic tendon pain: no signs of chemical inflammation but high concentrations of the neurotransmitter glutamate. Implications for treatment?

Chronic musculo-tendinous pain syndromes are relatively common and associated with very high socio-economic costs. Their aetiology and pathogenesis are still unknown. In the athletic population, chronic tendon pain is most often seen among recreational male and female athletes in the age group between 30-60 years, and is considered to be associated with overuse of the aged tendon. Treatment is known to be difficult. In general, these chronic painful conditions have been considered to include an inflammatory component, and the nomenclature used (tendinitis, tendonitis) most often implies an inflammatory involvement. Despite that tendon biopsies have shown an absence of inflammatory cell infiltration, anti-inflammatory agents (NSAID'S, corticosteroidal injections) are most often included in the treatment. Our research has been focused on chronic painful conditions in the Achilles-, patellar-, and extensor carpi radialis brevis (ECRB)-tendons. We have demonstrated, for the first time, that it is possible to use the microdialysis technique for in vivo investigations of human tendons, and that the excitatory neurotransmitter glutamate exists in human tendons. We have identified and measured the concentrations of prostaglandin E2 (PGE2) in tendons as well. The results showed that chronic painful tendinosis (Achilles-, patellar-, ECRB-) had significantly higher concentrations of glutamate, but not PGE2, as compared to the pain-free normal tendons. With the use of immunohistochemical analyses and enzyme histochemistry of human Achilles- and patellar tendon biopsies, we have also, for the first time demonstrated that glutamate NMDARI-immunoreaction was present in nerve structures. These findings altogether, indicate that glutamate might be involved in chronic tendon pain, and further emphasizes that there is no chemical inflammation (normal PGE2 levels) in the chronic stage of these relatively common so-called tendinopathies. The findings of glutamate and it's NMDARI-receptors might have implications for treatment and be a potential target for drugs.

Achilles tendinitis associated with fluoroquinolones

AIMS

To determine whether there is an association between use of fluoroquinolones and tendinitis in a large population under everyday circumstances.

METHODS

A retrospective cohort study was carried out in a dynamic population. Data came from the IPCI-database which consists of all data on consultations, morbidity, prescriptions and other interventions, as registered by GPs in a source population of approximately 250 000 persons. For this study data were collected from 41 general practices in the period from January 1st, 1995 through December 31st, 1996. All persons treated with either fluoroquinolones, amoxicillin, trimethoprim, cotrimoxazole or nitrofurantoin were followed from the first day of treatment until the outcome of interest, death, transfer to another practice, or end of the study period, whichever came first. The risk window was defined as the legend duration +1 month. Potential cases were defined as a registration of a tendinitis or tendon rupture. Patients with a history of tendinitis or tendon rupture, preceding trauma or inadequate diagnoses were excluded on the basis of a review of the patient profiles and additional clinical data, blinded as to the exposure status. Results were adjusted for age, gender, concurrent corticosteroid exposure and number of GP visits.

RESULTS

There were 1841 users of fluoroquinolones and 9406 users of the other antibacterial drugs with an average duration of 9 and 7 days, respectively. Tendinitis or tendon rupture was registered in 97 profiles, but after review only 22 complied with the case definition. The adjusted relative risk of tendinitis to fluoroquinolones was 3. 7 (95%CI: 0.9-15.1) for Achilles tendinitis and 1.3 (95%CI: 0.4-4.7) for other types of tendinitis. Achilles tendinitis to ofloxacin had a relative risk of 10.1 (95%CI: 2.2-46.0) and an excess risk of 15 cases per 100 000 exposure days.

CONCLUSIONS

Although the numbers in our study are small, our results suggest that some fluoroquinolones may increase the risk of Achilles tendinitis, and that this risk increase is highest for ofloxacin.

Adverse drug reactions related to the use of fluoroquinolone antimicrobials: an analysis of spontaneous reports and fluoroquinolone consumption data from three italian regions

OBJECTIVE

To analyse and compare with one another and with other antibacterial drugs the adverse drug reactions (ADRs) of the different fluoroquinolones currently used in Italy, spontaneously reported from doctors in three northern Italian regions.

METHODS

The data on fluoroquinolones and other antibacterials were obtained from the spontaneous reporting system database of Emilia Romagna, Lombardy and the Veneto, which are the principal contributors to the Italian spontaneous surveillance system. The fluoroquinolone ADRs with a causality assessment of certain, probable or possible (according to WHO criteria), reported between January 1999 and December 2001, were selected and toxicity profiles of individual drugs were described and compared with one another. The reports were also correlated with sex and age of patients and with regional prescription data to estimate individual fluoroquinolone reporting rate of adverse events.

RESULTS

During the study period, 10 011 reports were received by the system (a mean annual reporting rate of approximately 185 per million inhabitants): 1920 referred to systemic antimicrobials, of which 432 (22.5%) involved fluoroquinolones. Pefloxacin was associated with the highest reporting rate (982 reports/daily defined dose/1000 inhabitants/day), followed by moxifloxacin (356), rufloxacin (221) and lomefloxacin (196). The most frequently reported reactions to fluoroquinolones involved the skin, but their percentage (25%) was significantly lower (p < 0.01) than those of other systemic antimicrobials (58.5%), whereas the percentages of reactions involving the central nervous (12.2 vs 3.6%), musculoskeletal (14.7 vs 0.3%) and psychiatric systems (9.3 vs 1.8%) were significantly higher (p < 0.01). We found some significant differences in the safety profiles of individual fluoroquinolones: ciprofloxacin was more frequently associated with skin reactions (p < 0.01), levofloxacin and pefloxacin with musculoskeletal (p < 0.01), and rufloxacin with psychiatric disorders (p < 0.05). Levofloxacin was the fluoroquinolone associated with the highest rate of serious tendon disorders; phototoxic reactions were more frequent with lomefloxacin, and toxic epidermal necrolysis and Stevens-Johnson syndrome were seen only with ciprofloxacin.

CONCLUSIONS

The differences in the safety profiles should be taken into account when prescribing a fluoroquinolone to individual patients.

The effects of prolonged peritendinous administration of PGE1 to the rat Achilles tendon: a possible animal model of chronic Achilles tendinopathy

We studied the effects of peritendinous Achilles tendon injections of prostaglandin E1 (PGE1) on the Achilles tendon of rats. Five groups of Sprague-Dawley rats (n = 24 each) were studied. Groups 1 to 4 received weekly peritendinous injections. In group 1, one side was injected with 800 ng of PGE1 in 0.5 ml of 0.9% NaCl and the contralateral side was injected with 0.5 ml of 0.9% NaCl. In group 2, one side was injected with 800 ng of PGE1. In group 3, one side was injected with 0.5 ml of 0.9% NaCl. In group 4, a syringe needle was inserted in the peritenon unilaterally, but no substances were administered. In groups 2, 3, and 4, the contralateral tendon was used as the control. In group 5, treatment was not administered. Eight rats in each group were killed at each time point, after 7, 21, and 35 days of treatment. On day 7, values for average water content and average wet weight of the tendons treated with PGE1 were significantly higher than those in the control tendons (analysis of variance [ANOVA]; P = 0.02), with a histological picture of acute inflammation. On day 21, approximately half of the PGE1-treated tendons showed fibrosis of the paratenon, with adhesions and intra-tendinous degeneration, with the other half still showing a picture of acute inflammation. On day 35, all of the PGE1-treated tendons showed fibrosis of the paratenon, with adhesions and intra-tendinous degeneration. At all time points, there was no evidence of pathology in the tendons that had not received PGE1. Sham peritendinous injections and injections of normal saline did not produce inflammation in the Achilles tendons. Initially, local administration of PGE1 produced acute inflammation of the tendon and its surrounding tissues. Prolonged PGE1 administration produced peri- and intra-tendinous degeneration, providing a cheap, reproducible model of Achilles tendinopathy, which would allow studies of the effects of conservative and surgical management of the condition.

Vaccination-related shoulder dysfunction

We present two cases of shoulder pain and weakness following influenza and pneumococcal vaccine injections provided high into the deltoid muscle. Based on ultrasound measurements, we hypothesize that vaccine injected into the subdeltoid bursa caused a periarticular inflammatory response, subacromial bursitis, bicipital tendonitis and adhesive capsulitis. Resolution of symptoms followed corticosteroid injections to the subacromial space, bicipital tendon sheath and glenohumeral joint, followed by physical therapy. We conclude that the upper third of the deltoid muscle should not be used for vaccine injections, and the diagnosis of vaccination-related shoulder dysfunction should be considered in patients presenting with shoulder pain following a vaccination.

Partial Achilles tendon ruptures associated with fluoroquinolone antibiotics: a case report and literature review

Fluoroquinolone antibiotics (such as olprofloxacin, pefloxacin, ofloxacin, norfloxacin, temafloxacin, etc.) have recently been implicated in the etiology of Achilles tendinitis and subsequent tendon rupture. We report on a patient with bilateral partial Achilles tendon ruptures associated with ciprofloxacin therapy and present a review of the current literature on this increasingly recognized complication. Treatment with fluoroquinolones should be discontinued at the first sign of tendon inflammation so as to reduce the risk of subsequent rupture. Magnetic resonance imaging is useful in distinguishing between Achilles tendinitis and partial tendon rupture.

Cytokine-induced tendinitis: a preliminary study in rabbits

This study was designed to determine the effects of a single injection of a species-specific preparation of cytokines into rabbit patellar tendons and to compare the results with a known model of tendinitis, the collagenase-injection model. New Zealand White rabbits were divided into two groups and two time periods (4 and 16 weeks) and injected in the midsubstance of the right patellar tendon with either cytokines or collagenase under ultrasound guidance to confirm intratendinous needle placement. The left patellar tendon was injected with 0.025 ml of saline solution and served as a control. The rabbits were returned to cage activity after injection. At death, two rabbits in each group underwent histological analysis; the remaining eight animals in each time frame were evaluated biomechanically and then biochemically with use of the patella/whole patellar tendon/tibia complex. Histologic results at 4 weeks in the tendons injected with cytokines demonstrated increased cellularity, which was resolving by 16 weeks. The matrix appeared unchanged. The tendons injected with collagenase demonstrated increased angiogenesis of the matrix, hypercellularity, and fibrosis around the tendon at 4 weeks. At 16 weeks, myxoid changes, focal fibrosis, and collagen-bundle disarray with persistent increase in cellularity were noted. Biomechanically, a significant decrease in ultimate load at 16 weeks was seen in the tendons injected with cytokines but no change was seen in cross-sectional area. The tendons injected with collagenase demonstrated a significant increase in cross-sectional area at 4 and 16 weeks compared with those injected with cytokines. Biochemically, there was no significant difference in collagen content between the two groups at 4 or 16 weeks but the tendons injected with collagenase demonstrated a significant increase in crosslinking at 16 weeks. Our conclusion is that the tendons injected with the cytokine preparation represent a model of mild, seemingly reversible tendon injury. The cytokine preparation produces no matrix damage or evidence of collagen degradation and is species specific.

Four cases of tendinopathy in patients on statin therapy

During the last decade, statins have been widely prescribed as lipid-lowering drugs. Their overall safety profile is good. The main musculoskeletal side effects have consisted of muscle pain and weakness, peripheral neuropathy, and a few cases of drug-induced lupus. We report the first four cases of tendinopathy in patients receiving statin therapy. There were three men and one woman. The diagnoses were extensortenosynovitis at the hands (case 1), tenosynovitis of the tibialis anterior tendon (case 2), and Achilles tendinopathy (cases 3 and 4). Two patients were on simvastatin and two on atorvastatin. The tendinopathy developed 1 to 2 months after treatment initiation. The outcome was consistently favorable within 1 to 2 months after discontinuation of the drug. Similar cases have been reported to French pharmacovigilance centers. This report of four cases of tendinopathy draws attention to a possible and heretofore unrecognized side effect of a drug class that is becoming increasingly popular. Statins are effective in lowering high cholesterol levels in patients with type IIa or IIb hypercholesterolemia. They have been widely used for the last decade, particularly in the secondary and primary prevention of major coronary events. Statins act by inhibiting the enzyme hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase. Although most patients tolerate statins extremely well, a few experience side effects requiring treatment discontinuation. Reported musculoskeletal side effects include myalgia and a few cases of rhabdomyolysis and polymyositis. Induced lupus and peripheral neuropathy are exceedingly rare.

Fluoroquinolone-induced tendinopathy: what do we know?

Fluoroquinolones are relatively safe, effective antibiotics. As their use becomes more frequent, so will the adverse side effects. I highlight a rare but debilitating adverse reaction-fluoroquinolone-induced tendinopathy. Case reports and letters from 1987 to 1998 were identified by using Grateful Med and PubMed Internet accesses to the National Library of Medicine. Articles were reviewed for clinical practicality. There are few articles on fluoroquinolone-induced tendinopathy in the US literature targeting primary care physicians. This entity has been described in many case reports, but little has been done to isolate the causative agents. Incidence of this side effect is difficult to estimate, since no prospective studies are available for review or calculation of risk. Fluoroquinolone-induced tendinopathy appears more commonly in tendons under high stress. The cause is probably multifactorial. Risk factors for the development of fluoroquinolone-induced tendinopathy are age, renal failure, corticosteroid use, and previous tendinopathy from fluoroquinolones.

Musculoskeletal complications of fluoroquinolones: guidelines and precautions for usage in the athletic population

Fluoroquinolone antibiotics are associated with a wide spectrum of musculoskeletal complications that involve not only tendon but also cartilage, bone, and muscle. Insights into the pathoetiology of fluoroquinolone toxicity on musculoskeletal tissues have been evolving over recent years. Although the pathoetiology is certainly multifactorial, alterations in cell signaling proteins and direct toxic effects on musculoskeletal tissues have been strongly implicated. Increasing age and concomitant systemic corticosteroid use appear to significantly increase the risk of adverse events. The purpose of this article is to review the musculoskeletal complications associated with use of fluoroquinolone antibiotics by adults; identify risk factors associated with fluoroquinolone toxicity; explore the possible pathoetiology of fluoroquinolone toxicity on tendon, cartilage, bone, and muscle; and offer recommendations regarding evaluation and treatment of fluoroquinolone-associated musculoskeletal complications. In addition, this review will provide recommendations regarding fluoroquinolone use in athletes and return to play after fluoroquinolone exposure.

Rheumatological complications associated with the use of indinavir and other protease inhibitors

Several cases are reported of rheumatological pathology (temporomandibular dysfunction, frozen shoulder, Dupuytren's disease, and tendinitis) most probably related to the intake of indinavir in HIV positive patients. A survey using an anonymous questionnaire of 878 people with HIV infection treated with antiretroviral drugs suggests that other protease inhibitors may also cause arthralgia.