A rare case of symptomatic creatine kinase elevation in a patient with rheumatoid arthritis treated with baricitinib.

The safety profile of baricitinib (BARI), a Janus kinase inhibitor broadly used for the treatment of rheumatoid arthritis (RA), includes asymptomatic laboratory abnormalities, such as an increase in creatine kinase (CK). Data from randomized controlled trials suggest that concomitant myalgia is rare in RA and does not lead to drug discontinuation. We describe the case of a 68-year-old Caucasian female with longstanding, multi-failure RA who started BARI and achieved disease remission. However, she developed a symptomatic CK increase, as well as a parallel increase in total cholesterol, low-density lipoprotein, and triglycerides. Dechallenge-rechallenge demonstrated a plausible relationship between the clinical/laboratory abnormalities and BARI. In fact, when the drug was withdrawn, CK returned to normal and myalgia disappeared, whereas symptoms returned and CK levels increased when BARI was restarted. BARI may be rarely associated with symptomatic CK elevation, and this may pose clinical challenges, particularly for patients with multi-failure RA who achieved good disease control with BARI but required drug discontinuation due to intolerance.

Proton pump inhibitors and gastrointestinal symptoms among patients with COVID-19 infection.

INTRODUCTION: The administration of proton pump inhibitors (PPIs) is anticipated to elevate an individual's susceptibility to enteric infections as a result of altering the gut flora. The influence of PPIs on the clinical manifestation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still uncertain. This study aims to investigate the impact of PPI usage on the clinical manifestation of COVID-19, namely its gastrointestinal symptoms. METHODS: This is a cross-sectional cohort study involving COVID-19 patients. Patients were interviewed using a predesigned questionnaire that asked about their demographics, clinical manifestations of COVID-19 infection, and the extent and type of PPIs in use. PPI usage was confirmed by reviewing patients' electronic medical records. The primary outcome was to establish any association between the use of PPI and the symptoms and clinical presentation of COVID-19. RESULTS: Out of a total of 254 participants, 69 (27.2%) were considered PPI users. Patients who were on PPI medications reported a significantly lower rate of myalgia (27.5% vs 51.9%; p = 0.0006) and heartburn (5.7% vs 15.6%; p = 0.03) but had a significantly higher rate of abdominal pain (27.5% vs 13.5%; p = 0.001) and diarrhoea (28.9% vs 14.5%, p = 0.02) when compared to those who were not using PPIs. Patients on PPIs were also shown to have significantly higher odds of developing diarrhoea (OR 2.0, 95% CI: 1.08 to 3.93, p = 0.02) and abdominal pain (OR 2.0, 95% CI: 1.22 to 3.93, p = 0.03), but a lower risk of developing myalgia (OR 0.5, 95% CI: 0.3 to 0.9, p = 0.02) when compared to non-PPI users. CONCLUSION: This study shows that the use of PPIs could impact COVID-19 clinical presentation toward more gastrointestinal manifestations. Further studies investigating the link between other acid suppression medications and COVID-19 manifestations and severity should be carried out.

Safety of an inactivated COVID-19 vaccine (CoronaVac) in children aged 7-14 years in Taizhou, China.

Our study aimed to evaluate the safety of CoronaVac, an inactivated vaccine made by Sinovac, in children aged 7-14. We conducted a parent-administered online survey to monitor adverse reactions after vaccinating children in Taizhou, China, from February 15, 2021, to January 19, 2022. 767 parents completed the survey after receiving a questionnaire via WeChat. Overall, 15.3 % (117/767) of children experienced adverse effects after the first dose, and 12.2 % (88/724) after the second. Muscle pain was the most common adverse reaction post-first dose (10.0 %), while localized pain or itching at the injection site was most common after the second dose (7.6 %). In conclusion, the vaccine has a low incidence of side effects. The mild to moderate, transient, and common nature of these effects further boosts parents' confidence in vaccinating their children.

Venlafaxine-Associated Rhabdomyolysis: A Literature Review.

PURPOSE: This systematic review aimed to investigate the clinical manifestations and characteristics of venlafaxine-associated rhabdomyolysis. METHODS: A systematic search was conducted in PubMed, Elsevier, Science Direct, Embase, Springer Link, Wiley Online Library, CNKI, and Wanfang databases from the date of database inception to January 2023. Previously reported cases of venlafaxine-associated rhabdomyolysis were identified, and relevant data from these cases were collected for descriptive statistical analysis. Cases that met the inclusion criteria were evaluated to determine the correlation between adverse reactions and venlafaxine. RESULTS: A total of 12 patients with venlafaxine-associated rhabdomyolysis were included. None of these patients had a history of muscle pain or discomfort. Of the 12 patients, 5 patients received venlafaxine at doses of ≤225 mg/d, whereas the remaining 7 patients received doses exceeding 225 mg/d. The main clinical symptoms included myalgia, muscle weakness, and renal injury. All 12 patients discontinued venlafaxine and received symptomatic care. CONCLUSIONS: Venlafaxine, used either as a monotherapy or in combination with other drugs, may be associated with rhabdomyolysis. Creatine kinase levels may normalize or significantly decrease after discontinuation of venlafaxine and symptomatic treatment.

Short-term side effects of COVID-19 vaccines among healthcare workers: a multicenter study in Iran.

Since the initiation of the COVID-19 vaccination effort, there has been widespread concern regarding vaccine efficacy and potential side effects. This study aimed to explore the short-term side effects of four available COVID-19 vaccines (Sputnik V, Sinopharm, Oxford-AstraZeneca, and Covaxin) among healthcare workers (HCWs) in Iran. The multicenter study involved 1575 HCWs, with the majority received Sputnik V (74.1%), followed by Covaxin (15.6%), Sinopharm (6.4%), and Oxford-AstraZeneca (3.8%). The prevalence of at least one side effect after the first and second dose COVID-19 vaccine was 84.6% and 72.9%, respectively. The common side effects (presented in > 50% of the study participants) after the first dose of the vaccine were injection site pain (61.7%), myalgia (51.8%), and muscle pain (50.9%). The most reported side effects after the second dose of the vaccine were injection site pain (26.8%), myalgia (15.8%), fever (10.3%), headache (9.9%), and chills (9.2%). In conclusion, according to the COVID-19 vaccine type, different side effects might occur following the first and second doses of vaccination. These findings assist in addressing the ongoing problems of vaccination hesitancy which has been driven by widespread worries about the vaccine safety profile.

Are statins making older persons weaker? A discontinuation study of muscular side effects.

Thirteen percent of the Danish population are treated with a statin-half of these are in primary prevention, and most are > 65 years old. Statins have known muscular side effects (i.e., myalgia) correlated to reduced muscle performance. This study examines if years of statin treatment in older people introduce subclinical muscle discomfort and loss of muscle mass and strength. In total, 98 participants (71.1 ± 3.6 years (mean ± SD)), who were in primary prevention treatment for elevated plasma cholesterol with a statin, were included in this study. Statin treatment was discontinued for 2 months and then re-introduced for 2 months. Primary outcomes included muscle performance and myalgia. Secondary outcomes included lean mass and plasma cholesterol. Functional muscle capacity measured as a 6-min walk test increased after discontinuation (from 542 ± 88 to 555 ± 91 m, P < 0.05) and remained increased after re-introduction (557 ± 94 m). Similar significant results were found with a chair stand test (15.7 ± 4.3 to 16.3 ± 4.9 repetitions/30 s) and a quadriceps muscle test. Muscle discomfort during rest did not change significantly with discontinuation (visual analog scale from 0.9 ± 1.7 to 0.6 ± 1.4) but increased (P < 0.05) with the re-introduction (to 1.2 ± 2.0) and muscle discomfort during activity decreased (P < 0.05) with discontinuation (from 2.5 ± 2.6 to 1.9 ± 2.3). After 2 weeks of discontinuation, low-density lipoprotein cholesterol increased from 2.2 ± 0.5 to 3.9 ± 0.8 mM and remained elevated until the re-introduction of statins (P < 0.05). Significant and lasting improvements in muscle performance and myalgia were found at the discontinuation and re-introduction of statins. The results indicate a possible statin-related loss of muscle performance in older persons that needs further examination.

Efficacy and outcomes of Bempedoic acid versus placebo in patients with statin-intolerance: A pilot systematic review and meta-analysis of randomized controlled trials.

INTRODUCTION: Bempedoic acid (BA) has shown significant progress in reducing cholesterol levels and is relatively free from the many side effects encountered with the use of other hyperlipidemic drugs such as statins. However, its efficacy in patients with statin intolerance is controversial with inconsistent results among studies. MATERIALS AND METHODS: An electronic literature search was performed using various databases such as Medline, Google Scholar, and the International Registry of Clinical Trials. The primary endpoint was the change in LDL-C levels. The secondary endpoints included changes in HDL-C, non-HDL-C, triglycerides (TG), clinical outcomes such as MACE, all-cause mortality (ACM), cardiovascular mortality, myocardial infarction (MI), and additional safety outcomes. The least-square mean (LSM) percent change for assessing changes in lipid parameter levels from the baseline and the risk ratio (RR) were used for the evaluation of binary endpoints, with statistical significance set at p<0.05. Random-effects meta-analyses were performed for all the outcomes. RESULTS: Our analysis included 5 randomized controlled trials (RCTs) with a total of 18,848 participants. BA showed a significant reduction in LDL-C [LSM difference in %: -25.24; 95 % CI: -30.79 to -19.69; p < 0.00001], total cholesterol [LSM difference in %:-21.28; 95 % CI:-30.58 to-11.98; p < 0.00001], non-HDL-C [LSM difference in %: -23.27; 95 % Cl: -29.80 to -16.73 p < 0.00001], and HDL-C [LSM difference in %:-3.37, 95 % CI:-3.73 to-3.01, p < 0.00001] compared to placebo. In terms of clinical efficacy, BA was associated with a lower risk of coronary revascularization [RR:0.81; 95 % CI:0.66 to 0.99; p = 0.04], hospitalization for unstable angina [RR:0.67; 95 % CI:0.50 to 0.88; p = 0.005], and myocardial infarction [RR:0.76; 95 % CI:0.66 to 0.88;p = 0.0004]. No significant difference was observed in MACE [RR:0.81; p = 0.15], ACM [RR:0.86; p = 0.46], cardiovascular-related mortality [RR:0.79; p = 0.44], and stroke [RR:0.83; p = 0.08] between the two groups. In terms of safety efficacy, the risk for myalgia was significantly lower in BA-treated patients than in placebo [RR:0.80; p = 0.0002], while the risk for gout [RR:1.46; p < 0.0001] and hyperuricemia [RR:1.93; p < 0.00001] was higher for BA than for placebo. The risks for other adverse effects, such as neurocognitive disorder, nasopharyngitis urinary tract infection, upper respiratory infection, muscular disorder, and worsening hyperglycemia/DM were comparable between the two groups. CONCLUSION: Our analysis demonstrated that BA significantly reduced the levels of LDL-C, total cholesterol, non-HDL-C, HDL-C, ApoB, and hs-CRP compared with the placebo group. Additionally, patients who received BA had a lower likelihood of coronary revascularization and hospitalization due to unstable angina, MI, and myalgia. Further large-scale RCTs are required to generate more robust evidence.

Intolerance upon statin rechallenge: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Although statins are often discontinued when myalgia arises, a causal relationship may not always exist. How well-tolerated statins are when rechallenge is blinded and controlled is unclear. METHODS AND FINDINGS: We performed a systematic review and meta-analysis (PROSPERO CRD42023437648) to evaluate the success of statin rechallenge versus matched placebo in those who were previously statin intolerant. Our primary outcome was intolerance; our secondary outcome was the myalgia or global symptom score. Medline, Embase, CINAHL Plus, Scopus, and CENTRAL were searched from inception to May 1, 2023. Eligible trials were randomized controlled trials with parallel or crossover designs examining statin rechallenge in statin-intolerant adults. Two independent reviewers selected studies, extracted data, and assessed risk of bias (Cochrane Collaboration's risk-of-bias tool 1). Relative risk (RR) and mean difference (MD) were estimated using fixed effect Mantel-Haenszel statistics. Of 1,941 studies screened, 8 met our inclusion criteria (8 to 491 participants from Asia, Europe, North America, and Oceana). Compared to placebo, intolerance was more common in statin users [325/906 (36%) vs 233/911 (26%), RR 1.40, 95% CI, 1.23 to 1.60, I2 = 0%, 7 trials, number needed to harm 10] and there was no statistically significant difference in myalgia or global symptom score on a 100-point scale [MD 1.08, 95% CI, -1.51 to 3.67, I2 = 0%, 5 trials]. Limitations include only 1 trial asking participants about intolerable symptoms (vs inferring intolerance from discontinuation or trial withdrawal); the small number of trials; the possibility of attrition bias; and the potential for carryover effects in crossover/n-of-1 trial designs. CONCLUSIONS: Of those previously intolerant of statins who were rechallenged with a statin and compared to placebo recipients, medication intolerance was more common amongst statin recipients. However, there was no significant difference in mean myalgia or global symptom score between statin and placebo, and only one-third of those previously believed to be statin intolerant were unable to tolerate a statin on blinded rechallenge; one-quarter were intolerant of placebo.

Effects of conditioned pain modulation on Capsaicin-induced spreading muscle hyperalgesia in humans.

OBJECTIVES: Muscle pain can be associated with hyperalgesia that may spread outside the area of primary injury due to both peripheral and central sensitization. However, the influence of endogenous pain inhibition is yet unknown. This study investigated how endogenous pain inhibition might influence spreading hyperalgesia in experimental muscle pain. METHODS: Conditioned pain modulation (CPM) was assessed in 30 male volunteers by cold pressor test at the non-dominant hand as conditioning and pressure pain thresholds (PPT) at the dominant 2nd toe as test stimuli. Subjects were classified as having inhibitory or facilitating CPM based on published reference values. Subsequently, muscle pain and hyperalgesia were induced by capsaicin injection into the non-dominant supraspinatus muscle. Before and 5, 10, 15, 20, 30, 40, 50 and 60 min later, PPTs were recorded at the supraspinatus, infraspinatus and deltoid muscle, ring finger and toe. RESULTS: Compared to baseline, PPTs decreased at the supraspinatus, infraspinatus and deltoid muscle (p≤0.03), and increased at the finger and toe (p<0.001). In facilitating CPM (n=10), hyperalgesia occurred at 5, 10, 15, 20 and 40 min (p≤0.026). In inhibitory CPM (n=20), hyperalgesia only occurred after 10 and 15 min (p≤0.03). At the infraspinatus muscle, groups differed after 5 and 40 min (p≤0.008). CONCLUSIONS: The results suggest that facilitating CPM is associated with more spreading hyperalgesia than inhibitory CPM. This implies that poor endogenous pain modulation may predispose to muscle pain and spreading hyperalgesia after injury, and suggest that strategies to enhance endogenous pain modulation may provide clinical benefits.

P2X7-NLRP3-Caspase-1 signaling mediates activity-induced muscle pain in male but not female mice.

ABSTRACT: We developed an animal model of activity-induced muscle pain that is dependent on local macrophage activation and release of interleukin-1ß (IL-1ß). Activation of purinergic type 2X (P2X) 7 receptors recruits the NOD-like receptor protein (NLRP) 3 and activates Caspase-1 to release IL-1ß. We hypothesized that pharmacological blockade of P2X7, NLRP3, and Caspase-1 would prevent development of activity-induced muscle pain in vivo and release of IL-1ß from macrophages in vitro. The decrease in muscle withdrawal thresholds in male, but not female, mice was prevented by the administration of P2X7, NLRP3, and Caspase-1 inhibitors before induction of the model, whereas blockade of IL-1ß before induction prevented muscle hyperalgesia in both male and female mice. Blockade of P2X7, NLRP3, Capsase-1, or IL-1ß 24 hours, but not 1 week, after induction of the model alleviated muscle hyperalgesia in male, but not female, mice. mRNA expression of P2X7, NLRP3, Caspase-1, and IL-1ß from muscle was increased 24 hours after induction of the model in both male and female mice. Using multiplex, increases in IL-1ß induced by combining adenosine triphosphate with pH 6.5 in lipopolysaccharide-primed male and female macrophages were significantly lower with the presence of inhibitors of P2X7 (A740003), NLRP3 (MCC950), and Caspase-1 (Z-WEHD-FMK) when compared with the vehicle. The current data suggest the P2X7/NLRP3/Caspase-1 pathway contributed to activity-induced muscle pain initiation and early maintenance phases in male but not female, and not in late maintenance phases in male mice.

Vascular endothelial growth factor-A is involved in intramuscular carrageenan-induced cutaneous mechanical hyperalgesia through the vascular endothelial growth factor-A receptor 1 and transient receptor potential vanilloid 1 pathways.

OBJECTIVES: Vascular endothelial growth factor-A (VEGF-A) plays a leading role in angiogenesis and pain hypersensitivity in cancer and chronic pain. It is not only induced by ischemic conditions but is also highly correlated with proalgesic cytokines, both of which are prominent in inflammatory muscle pain. However, the molecular basis of the involvement of VEGF-A in muscle pain remains unknown. METHODS: In the present study, we performed behavioral and pharmacological analyses to determine the possible involvement of VEGF-A in the development of inflammatory muscle pain and the associated signal transduction pathway. RESULTS: Unilateral intramuscular injection of carrageenan, a classical model of inflammatory muscle pain, increased VEGF-A gene expression in the tissues surrounding the injection site. Intramuscular administration of recombinant VEGF-A165 on the same side induced cutaneous mechanical hyperalgesia during the acute and subacute phases. The application of a specific VEGFR1 antibody on the same side significantly reduced the mechanical hyperalgesia induced by carrageenan or VEGF-A165 injection, whereas both a VEGFR2-neutralizing antibody and a VEGFR2 antagonist showed limited effects. Local preinjection of capsazepine, a transient receptor potential vanilloid 1 (TRPV1) antagonist, also inhibited VEGF-A165-induced hyperalgesia. Finally, intramuscular VEGF-A165-induced mechanical hyperalgesia was not found in TRPV1 knockout mice during the subacute phase. CONCLUSIONS: These findings suggest that inflammatory stimuli increase interstitial VEGF-A165, which in turn induces cutaneous mechanical pain via the VEGFR1-mediated TRPV1 nociceptive pathway during inflammatory muscle pain. VEGFR1 could be a novel therapeutic target for inflammation-induced muscle pain.

Ritodrine-induced rhabdomyolysis and psychiatric symptoms: a case report and literature review.

BACKGROUND: Ritodrine hydrochloride, a ß2-adrenergic agonist, has been widely used in Asia and Europe to treat preterm labor in pregnant women. It has some typical side effects, such as palpitations, pulmonary edema, and hypokalemia. Here, we report a case of rhabdomyolysis and psychiatric symptoms might be associated with intravenous ritodrine. CASE PRESENTATION: A 32-year-old Chinese primigravida woman who was pregnant with twins by in vitro fertilization-embryo transfer was diagnosed with placenta previa and threatened abortion at 21 gestational weeks (GW). The patient was then treated with ritodrine hydrochloride. The initial dose of ritodrine was 150 µg/min, gradually increasing to 360 µg/min at 235/7 GW and 400 µg/min at 271/7 GW. Magnesium sulfate was added to the ritodrine regimen at 215/7 GW in dosage of 1-2 g/h. Psychiatric symptoms appeared at 245/7, 265/7, and 273/7 GW, manifesting as depression, anxiety, and suicidal tendencies. Severe muscle pain in her limbs and general weakness appeared after six weeks of ritodrine administration, which might have been a sign of rhabdomyolysis resulting from ritodrine administration. After ceasing the administration of ritodrine, the muscle pain and relevant data from laboratory tests on the patient were significantly improved, and her mood was stable. It is worth noting that this is the first time to report psychiatric symptoms may associated with the administration of ritodrine. In addition, we reviewed and analyzed six reported cases of rhabdomyolysis caused by ritodrine. CONCLUSION: Our results suggest that we should pay more attention to the risk of rhabdomyolysis and psychiatric symptoms induced by intravenous ritodrine hydrochloride, especially in patients with a history of neuromuscular disorder, or concomitant use of magnesium sulfate.

Statins increase muscle pain or weakness at 1 y, with an absolute excess of 11 events/1000 person-y.

SOURCE CITATION: Cholesterol Treatment Trialists' Collaboration. Effect of statin therapy on muscle symptoms: an individual participant data meta-analysis of large-scale, randomised, double-blind trials. Lancet. 2022;400:832-45. 36049498.

Adverse Events Associated with Encorafenib Plus Cetuximab in Patients with BRAFV600E-mutant Metastatic Colorectal Cancer: An in-depth Analysis of the BEACON CRC Study.

BACKGROUND: The BRAF inhibitor encorafenib in combination with cetuximab was recently approved for patients with BRAFV600E-mutated (BRAFV600Emut) metastatic colorectal cancer (mCRC). Approval was based on positive results from the phase 3 BEACON CRC study in BRAFV600Emut mCRC patients who had progressed after 1-2 previous regimens. This analysis provides a detailed examination of the adverse events (AEs) of interest (AEIs) with encorafenib+cetuximab in the BEACON study to aid gastrointestinal oncologists, given the limited experience with this combination. MATERIALS AND METHODS: AEIs, including dermatological AEs, arthralgia/myalgia, nausea/vomiting, diarrhea, abdominal pain, fatigue/asthenia and nephrotoxicity, were examined in the doublet therapy group. Clinical characteristics associated with these AEs, AE grade, time to onset and time to resolution were also studied. RESULTS: Safety analysis included 216/220 patients randomized to doublet therapy. The most commonly occurring AEI was dermatological toxicity (75.5%), followed by arthralgia/myalgia (56.0%) and fatigue/asthenia (56.0%). Other than nephrotoxicity (7 patients; 5/7 with Grade 3 or 4), most AEs were Grade 1 or 2. Most AEs were more common in women than men (nausea/vomiting, diarrhea, abdominal pain, dermatological AEs, and arthralgia/myalgia). Nausea/vomiting, abdominal pain and fatigue/asthenia were more common in patients aged ≥70 years. Most AEs developed early, within the first 1-2 months of treatment, and resolved within 1-2 weeks. In addition, survival outcomes were better in patients experiencing arthralgia/myalgia or dermatological toxicities. CONCLUSION: This analysis indicated that, except for rare cases of nephrotoxicity, encorafenib+cetuximab is well tolerated in most patients, with most AEIs being mild-to-moderate in severity, occurring early and resolving rapidly. CLINICAL TRIAL REGISTRATION: the BEACON study (ClinicalTrials.gov, NCT02928224; EudraCT, 2015-005805-35).

Side effects of statins: from pathophysiology and epidemiology to diagnostic and therapeutic implications.

Treatment with statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, has proven beneficial preventive effects on cardiovascular events. However, discontinuation due to intolerance and non-adherence remain two of the major gaps in both primary and secondary prevention. This leads many patients with high-risk of atherosclerotic cardiovascular disease (ASCVD) to be inadequately treated or not to achieve target lipid level goals, and as consequence they undergo an increased risk of cardiovascular events. The aim of this review is thus to give an overview of the reasons for discontinuation and on the possible mechanisms behind them. Although statins, as a class, are generally safe, they are associated with an increased risk of diabetes mellitus and hepatic transaminase elevations. Incidence of cataracts or cognitive dysfunction and others presented in the literature (e.g. proteinuria and haematuria) have been never confirmed to have a causal link. Conversely, debated remains the effect on myalgia. Muscle side effects are the most commonly reported, although myalgia is still believed by some to be the result of a nocebo/drucebo effect. Concerning mechanisms behind muscular side effects, no clear conclusions have been reached. Thus, if on one side it is important to identify individuals either at higher risk to develop a side effect, or with confirmed risk factors and conditions of statin intolerance, on the other side alternative strategies should be identified to avoid an increased ASCVD risk.

Selective androgen receptor modulator microparticle formulation reverses muscle hyperalgesia in a mouse model of widespread muscle pain.

ABSTRACT: Chronic pain is a significant health problem associated with disability and reduced quality of life. Current management of chronic pain is inadequate with only modest effects of pharmacological interventions. Thus, there is a need for the generation of analgesics for treating chronic pain. Although preclinical and clinical studies demonstrate the analgesic effects of testosterone, clinical use of testosterone is limited by adverse androgenic effects. Selective androgen receptor modulators (SARMs) activate androgen receptors and overcome treatment limitations by minimizing androgenic side effects. Thus, we tested whether daily soluble SARMs or a SARM-loaded microparticle formulation alleviated muscle hyperalgesia in a mouse-model of widespread pain (male and female C57BL/6J mice). We tested whether the analgesic effects of the SARM-loaded microparticle formulation was mediated through androgen receptors by blocking androgen receptors with flutamide pellets. In vitro and in vivo release kinetics were determined for SARM-loaded microparticles. Safety and toxicity of SARM treatment was determined using serum cardiac and liver toxicity panels, heart histology, and conditioned place preference testing. Subcutaneous daily SARM administration, and 2 injections, 1 week apart, of SARM-loaded microparticles alleviated muscle hyperalgesia in both sexes and was prevented with flutamide treatment. Sustained release of SARM, from the microparticle formulation, was observed both in vitro and in vivo for 4 weeks. Selective androgen receptor modulator treatment produced no cardiac or liver toxicity and did not produce rewarding behaviors. These studies demonstrate that SARM-loaded microparticles, which release drug for a sustained period, alleviate muscle pain, are safe, and may serve as a potential therapeutic for chronic muscle pain.

Are Chronic Pain Syndromes the Reason for Statin-associated Muscle Symptoms?

BACKGROUND: Statin-induced myalgia is defined as muscle pain without elevation of serum creatine phosphokinase levels and is a well-known complaint among statin users. Chronic pain syndromes affect a high percentage of the population. These pain syndromes may confound the reports of statin-induced myalgia. OBJECTIVES: To compare the occurrence of chronic pain among patients on statin therapy who developed myalgia with those who did not. METHODS: This study included 112 statin-treated patients, who were followed at the lipid center at Sheba Medical Center. Fifty-six patients had a diagnosis of statin-associated muscle symptoms (SAMS) and 56 did not. Verified questionnaires were used to assess the diagnoses of fibromyalgia, pain intensity, functional impairment, anxiety, and depression in the study population. RESULTS: Patients with statin myalgia were more likely to fulfil the diagnostic criteria for fibromyalgia than patients without statin myalgia (11 [19.6%] vs. 0, respectively). Patients in the SAMS group exhibited higher levels of anxiety and depression compared with the control group. Female sex, higher scores on the Brief Pain Inventory pain intensity scale, and a Hamilton rating scale level indicative of an anxiety disorder were found to be significant predictors for fibromyalgia in patients presenting with statin myalgia. CONCLUSIONS: A significant percentage of patients diagnosed with statin myalgia fulfilled the diagnostic criteria for fibromyalgia depression or anxiety disorder. Detection of these patients and treatment of their primary pain disorders or psychiatric illnesses has the potential to prevent unnecessary cessation of effective statin therapy.