Lack of effect of indomethacin on ordered growth of the femur in rats

The effect of NSAIDs on postfracture bone healing: a meta-analysis of randomized controlled trials

To determine whether nonsteroidal anti-inflammatory drugs (NSAIDs) have an adverse effect on bone healing by evaluating all available human randomized controlled trials (RCTs) on this subject.

Data Sources

A comprehensive search of electronic databases (PubMed, MEDLINE, and Cross-References) until October 2018 comparing the occurrence of nonunion in patients who received NSAIDs to the control group through RCTs.

Study Selection

Inclusion criteria were English-only studies, and the type of studies was restricted to RCTs.

Data Extraction

Two authors independently extracted data from the selected studies, and the data collected were compared to verify agreement.

Data Synthesis

Nonunion was the main outcome evaluated in each study. Regression analysis was used to estimate the relative risk comparing the duration and the type of NSAIDs by calculating the odds ratio (OR) for dichotomous variables. Studies were weighed by the inverse of the variance of the outcome, and a fixed-effects model was used for all analyses.

Conclusions

Six RCTs (609 patients) were included. The risk of nonunion was higher in the patients who were given NSAIDs after the fracture with an OR of 3.47. However, once the studies were categorized into the duration of treatment with NSAIDs, those who received NSAIDs for a short period (<2 weeks) did not show any significant risk of nonunion compared to those who received NSAIDs for a long period (>4 weeks). Indomethacin was associated with a significant higher nonunion rate and OR ranging from 1.66 to 9.03 compared with other NSAIDs that did not show a significant nonunion risk.

Do nonsteroidal anti-inflammatory drugs affect bone healing? A critical analysis

Nonsteroidal anti-inflammatory drugs (NSAIDs) play an essential part in our approach to control pain in the posttraumatic setting. Over the last decades, several studies suggested that NSAIDs interfere with bone healing while others contradict these findings. Although their analgesic potency is well proven, clinicians remain puzzled over the potential safety issues. We have systematically reviewed the available literature, analyzing and presenting the available in vitro animal and clinical studies on this field. Our comprehensive review reveals the great diversity of the presented data in all groups of studies. Animal and in vitro studies present so conflicting data that even studies with identical parameters have opposing results. Basic science research defining the exact mechanism with which NSAIDs could interfere with bone cells and also the conduction of well-randomized prospective clinical trials are warranted. In the absence of robust clinical or scientific evidence, clinicians should treat NSAIDs as a risk factor for bone healing impairment, and their administration should be avoided in high-risk patients.

Non-steroidal anti-inflammatory drugs, cyclooxygenase-2 and the bone healing process

Traditional non-steroidal anti-inflammatory drugs (NSAID) and selective cyclooxygenase-2 (COX-2) inhibitors are widely used in the treatment of pain, including bone fracture pain and orthopaedic post-operative pain. The gastrointestinal and cardiovascular adverse effects of NSAIDs are acknowledged, but their effects on bone are less widely known. Prostaglandins play an important role in the regulation of osteoblast and osteoclast functions, and inhibition of prostaglandin production retards bone formation. Therefore, NSAIDs could be expected to have significant consequences in divergent clinical situations where bone formation or remodelling is a contributing factor. The present survey reviews current experimental and clinical evidence related to two of those conditions (i.e. on ectopic bone formation and on bone fracture healing). NSAIDs are used clinically to prevent ectopic bone formation (also known as heterotopic ossification) (e.g. after total hip arthroplasty or trauma). The efficacy of NSAIDs in the avoidance of heterotopic ossification has been documented in controlled clinical trials, but the inherent risks (e.g. on healing processes and on loosening of prostheses) need further studies. At the same time, NSAIDs are widely used in the treatment of fracture pain, and their inhibitory effects on the ongoing bone healing process have raised concerns. Results of fracture healing studies in animals treated with NSAIDs or in mice lacking COX-2 gene show that inhibition or deficiency of COX-2 impairs the bone healing process. The limited clinical data also support the assumption that inhibition of COX-2 by non-selective or COX-2-selective NSAIDs delays fracture healing. However, the clinical significance of the effect in various patient groups needs to be carefully assessed and further investigations are needed to characterize the patients at the highest risk for NSAID-induced delayed fracture healing and its complications. In the meantime, use of NSAIDs in fracture patients should be cautious, keeping in mind the benefits of pain relief and inhibition of ectopic bone formation on one hand, and the risks of non-union and retarded union on the other hand.

Pharmacologic agents in fracture healing

Bone fractures are a known risk of athletic participation and can result in significant lost playing time. A variety of medications have been investigated in animal studies regarding their effects on fracture healing. Parathyroid hormone and the bisphosphonates may have future uses in the prevention and treatment of athletic-related stress fractures and acute fractures. Nonsteroidal anti-inflammatory drugs have been implicated in effecting fracture healing in some animal models, but little clinical evidence supports these findings. Large randomized clinical trials are needed to further delineate the role of these and other drugs and their effects on fracture healing.

Do non-steroidal anti-inflammatory drugs adversely affect stress fracture healing? A short review

A literature search was performed to determine whether non-steroidal anti-inflammatory drugs (NSAIDs) adversely affect the healing of stress fractures. Evidence exists from laboratory studies and animal subjects that NSAIDs can affect fracture healing. This link has not been proved or disproved in human subjects, particularly for stress fractures. In view of the high usage of NSAIDs in treating musculoskeletal disorders, research is required to investigate whether the healing of stress fractures is affected by these drugs.

Effect of diclofenac sodium on union of tibial fractures in rats

Nonsteroidal anti-inflammatory drugs are often used for 7 to 10 days after fracture because of their effects on bone metabolism. This study evaluated the effect of diclofenac sodium, administered at clinical dosage and duration, on bone union. Fifty-four male Wistar rats were randomly and equally divided into three groups: control, diclofenac 1 mg, and diclofenac 2 mg. Closed diaphyseal fractures were induced in the right tibias of all rats; the two diclofenac groups received intramuscular injections in the contralateral hips for 10 days. All animals were immobilized in circular casts on the upper thighs. Six rats in each group were sacrificed at weeks 2, 4, and 6, and bony union was evaluated clinically, radiologically, and histologically. At the end of 2 weeks, clinical examinations showed subjective differences between the two treated groups and control animals, with more stable callus formation in controls. Radiologic evaluation of the callus showed numeric, but not significant, differences between control and treated animals. At 4 and 6 weeks, clinical and radiologic findings were comparable among groups. Histologically, no significant differences in callus formation were evident at any evaluation.

Ketorolac in the Era of Cyclo-Oxygenase-2 Selective Nonsteroidal Anti-Inflammatory Drugs: A Systematic Review of Efficacy, Side Effects, and Regulatory Issues

OBJECTIVE

The recent introduction of oral COX-2 selective NSAIDs with potential for perioperative use, and the ongoing development of intravenous formulations, stimulated a systemic review of efficacy, side effects, and regulatory issues related to ketorolac for management of postoperative analgesia.

DESIGN

To examine the opioid dose sparing effect of ketorolac, we compiled published, randomized controlled trials of ketorolac versus placebo, with opioids given for breakthrough pain, published in English-language journals from 1986-2001. Odds ratios were computed to assess whether the use of ketorolac reduced the incidence of opioid side effects or improved the quality of analgesia.

RESULTS

Depending on the type of surgery, ketorolac reduced opioid dose by a mean of 36% (range 0% to 73%). Seventy percent of patients in control groups experienced moderate-severe pain 1 hour postoperatively, while 36% of the control patients had moderate to severe pain 24 hours postoperatively. Analgesia was improved in patients receiving ketorolac in combination with opioids. However, we did not find a concomitant reduction in opioid side effects (e.g., nausea, vomiting). This may be due to studies having inadequate (to small) sample sizes to detect differences in the incidence of opioid related side effects. The risk for adverse events with ketorolac increases with high doses, with prolonged therapy (>5 days), or invulnerable patients (e.g. the elderly). The incidence of serious adverse events has declined since dosage guidelines were revised.

CONCLUSIONS

Ketorolac should be administered at the lowest dose necessary. Analgesics that provide effective analgesia with minimal adverse effects are needed.

Dose-response of ketorolac as an adjunct to patient-controlled analgesia morphine in patients after spinal fusion surgery

This randomized, blind study was designed to determine the appropriate dose of ketorolac (a drug used as a supplement to opioids) to administer to patients who have undergone spinal stabilization surgery. The ketorolac was administered every 6 h, in addition to patient-controlled analgesia (PCA) with morphine, to 70 inpatients undergoing spine stabilization by one surgeon. The study was performed to determine the analgesic efficacy and incidence of side effects with different doses of ketorolac. The patients were divided into seven groups. They were given either i.v. saline (control group) or i.v. ketorolac (5, 7.5, 10, 12.5, 15, or 30 mg) every 6 h. The outcomes measured included pain scores, 24-h morphine usage, level of sedation, and side effect profile six times during the first 24 h postoperatively. The total dose of morphine was significantly larger in the control and 5 mg ketorolac groups than in the other five groups. Morphine consumption was similar in all groups receiving > or = 7.5 mg of ketorolac. The pain scores were significantly higher in the control group than in some of the larger dose groups at three of the study intervals. The 5 mg group had higher pain scores than the other groups at most of the time intervals studied. There were no significant differences in pain scores among the other five groups. Sedation scores were higher (i.e., patients were more sedated) in the control group than in the other six groups at three of the time periods. We conclude that the administration of ketorolac 7.5 mg every 6 h has a morphine-sparing effect equivalent to that of larger doses in patients undergoing spine stabilization surgery. Using larger doses of ketorolac did not result in less somnolence, lower morphine use, or less pain. We recommend that ketorolac 7.5 mg be given every 6 h to patients undergoing spinal fusion surgery in addition to PCA morphine.

IMPLICATIONS

Using smaller doses of ketorolac (e.g., 7.5 mg every 6 h) as a supplement to morphine patient-controlled analgesia is as effective as larger doses in patients who have undergone spine stabilization surgery.

The effect of postoperative nonsteroidal anti-inflammatory drug administration on spinal fusion

STUDY DESIGN

The influence of ketorolac on spinal fusion was studied in a retrospective review of 288 patients who underwent an instrumented spinal fusion.

OBJECTIVE

To assess the effect of postoperative ketorolac administration on subsequent fusion rates.

SUMMARY OF BACKGROUND DATA

Nonsteroidal anti-inflammatory drugs are widely used compounds, which are known to inhibit osteogenic activity and have been shown to decrease spinal fusion in an animal model. No previous studies have examined the influence of nonsteroidal anti-inflammatory drugs on spinal fusion in clinical practice.

METHODS

The medical records of 288 patients who underwent instrumented spinal fusion from L4 to the sacrum between 1991 and 1993 were reviewed retrospectively. The 121 patients who received no nonsteroidal anti-inflammatory drugs were compared with the 167 patients who received ketorolac after surgery. The groups were demographically equivalent.

RESULTS

Ketorolac had a significant adverse effect on fusion, with five nonunions in the nondrug group and 29 nonunions in the ketorolac group (P > 0.001). Ketorolac administration also significantly decreased the fusion rate for subgroups including men, women, smokers, and nonsmokers. The odds ratio demonstrated that nonunion was approximately five times more likely after ketorolac administration. Cigarette smoking also decreased the fusion rate (P > 0.01); smokers were 2.8 times more likely to develop nonunion.

CONCLUSION

These data suggest that nonsteroidal anti-inflammatory drugs significantly inhibit spinal fusion at doses typically used for postoperative pain control. The authors recommend that these drugs be avoided in the early postoperative period.

The effects of nonsteroidal anti-inflammatory drugs on posterior spinal fusions in the rat

STUDY DESIGN

This was a prospective study to determine the potential effects of indomethacin on spinal fusions in the rat.

OBJECTIVES

To determine if indomethacin exerts a deleterious effect on spinal fusions in the rat model.

SUMMARY OF BACKGROUND DATA

Nonsteroidal anti-inflammatory drugs are a class of compound that affect bone osteogenesis during fracture healing and heterotopic ossification. Spinal fusion is a process that occurs via osteogenesis and, therefore, may be similarly affected.

METHODS

Thirty-nine adult, Sprague-Dawley rats underwent a three-level posterior spinal fusion. Fusion was performed using morselized autogenous vertebral bone graft obtained via caudectomy and stabilized using a cerclage wiring technique. The 39 rats were divided into two groups consisting of 17 study animals and 22 control animals. The control group was injected with 1.5 cc of 0.9 normal saline subcutaneously for 12 weeks, whereas the test animals were injected on an identical schedule using 3 mg/kg of indomethacin sodium salt. Two control animals died, and three animals in the treatment group died of drug-related complications. Twelve weeks after surgery, all animals were killed, and the involved spinal segments were evaluated by direct manual examination. A fusion was probable if the spinal segments exhibited decreased scaled micromotion.

RESULTS

Sixty segmental levels in 20 control animals were assessed. Overall, 27 of 60 levels (45%) achieved fusion. In the indomethacin-treated group, 42 levels in 14 animals were evaluated. Overall, four of 42 levels (10%) achieved a fusion. Chi-square analysis demonstrated a significant difference (P < 0.001) between the control and indomethacin-treated groups.

CONCLUSIONS

This study raises serious questions about the inhibitory effects of nonsteroidal anti-inflammatory drugs on spinal fusion. Clinically, the widespread use of nonsteroidal anti-inflammatory drugs in the postoperative period after spinal fusion may need to be avoided.

Quantitative analysis of angiogenesis and growth of bone: effect of indomethacin exposure in a combined in vitro-in vivo approach

Nonsteroidal anti-inflammatory agents have been used experimentally and clinically to suppress a variety of physiological events, including angiogenesis and formation of bone. The exact mechanisms by which indomethacin alters skeletal tissue generation are unknown, due in part to methodological limitations. By the use of an organ culture assay and an animal model using intravital microscopy in mice bearing dorsal skinfold chambers, the effect of indomethacin on growth and angiogenesis of neonatal femora was characterized over 16 days. In both assays, femora significantly elongated with time (P < 0.05). The in vitro growth rate was more rapid than in vivo and dependent on the serum concentration, culture medium and age of mice. Although enhancing the serum content promoted cellular proliferation in organ culture, it dose-dependently suppressed femoral elongation, leading at 20% fetal calf serum to growth rates identical to those observed in vivo. Indomethacin supplementation (2 and 10 mg l-1) significantly accelerated longitudinal femoral growth in organ culture (P < 0.05), whereas in vivo indomethacin (2 mg kg-1) did not modulate either angiogenesis or elongation of bone. Our in vitro data propose a central role of serum in the regulation of bone formation. Although indomethacin altered femoral growth in vitro, our findings do not suggest that indomethacin suppresses angiogenesis or growth of bone in vivo. The complexity of physiological events in vivo may be obscuring a detectable effect.

Influence of indomethacin on bone turnover related to orthodontic tooth movement in miniature pigs

The purpose was to evaluate the influence of a prostaglandin inhibitor, indomethacin, on the tissue reaction related to orthodontic tooth movement. Sixteen miniature pigs were chosen for the study, eight of which received indomethacin perorally every day of the 39-day observation period. Sentalloy expansion springs (GAC, Central Islip, N.Y.) delivering 100 cN were inserted on a segmented arch between the central lower incisors. Intravital labeling with tetracycline was used for the evaluation of the rate of bone formation. After the pigs were killed, the bone turnover was evaluated on undecalcified methacrylate embedded sections and on microradiographs. The histomorphometric analysis of bone turnover revealed that the relative extent of resorption surfaces was decreased significantly in the indomethacin treated animals. Formation surfaces were also decreased although not significantly. The bone turnover, but not the mineralization rate, was influenced. The results corroborate the recommendation that prostaglandin inhibitors should be avoided during orthodontic treatments.

Influence of indomethacin on the regeneration of cortical bone within titanium implants in rabbits

The influence of indomethacin on cortical bone regeneration was studied in bone harvest chambers made of commercially pure titanium and inserted in rabbit tibia. Newly formed bone was harvested in situ every 3 wk for 33 wk. Indomethacin (1 mg/kg body weight) was given daily as subcutaneous injections for two periods, followed by two control periods with no drug administration and the same schedule was followed for indomethacin at a dose of 4 mg/kg body weight. These indomethacin dosages did not statistically influence the cortical bone regeneration.

[99mTc]diphosphonate uptake and hemodynamics in experimental arthritis: effect of naproxen in the canine carrageenan injection model

The impact of naproxen treatment on juxta-articular hemodynamics and bone metabolism in experimental juvenile arthritis was studied in the articular carrageenan injection model. Unilateral gonarthritis was induced for 12 weeks in eight dogs receiving naproxen (dosage, 2 mg/kg) and eight controls. Regional blood flow was assessed by the microsphere method, plasma volume by the distribution space of [125I]fibrinogen, and bone metabolism by the 2-h uptake of [99mTc]diphosphonate ([99mTc]DPD). Synovial effusion was less prominent with naproxen treatment as judged by joint fluid volume and pressure. Naproxen reduced the arthritic capsular hyperemia, almost normalized a severe blood flow increase in patella and both juxta-articular epiphyses, ameliorated an expansion of plasma volume in the patella and the distal femoral epiphysis, and normalized an increased [99mTc]DPD uptake in subchondral femoral bone and the tibial cortex. Significantly increased arteriovenous shunting in the arthritic extremity was unaffected by naproxen. The study suggests that long-term cyclooxygenase inhibition offers protection against hemodynamic and metabolic changes in juxta-articular bone secondary to synovial inflammation.

The suppression of heterotopic ossification after total hip arthroplasty

In a double-blind prospective randomised study we examined the effects of Diclofenac on heterotopic ossification after hip arthroplasty. Either the drug, or a placebo, was given by mouth to 158 patients in doses of 3 x 50 mg for 6 weeks. Diclofenac resulted in highly significant improvement (p less than 0.0001 versus controls) without severe side-effects. Heterotopic ossification decreased from 55% in the placebo to 15%. Significant degrees of heterotopic ossification did not occur with the drug. Movement of the hip was considerably increased after operation. We recommend Diclofenac prophylaxis against heterotopic ossification after hip operations in view of the serious clinical effects of this complication and its quoted incidence of 15% to 80%.

Effects of indomethacin on demineralized bone-induced heterotopic ossification in the rat

Indomethacin inhibits bone formation when treatment is initiated before the implantation of demineralized bone matrix (DBM). For the inhibition of bone induction to occur, indomethacin treatment had to be initiated 6 h or more before implantation of DBM. Initiating the drug treatment at or after the time of DBM implantation had no effects on the amounts of new bone formed. The inhibition by indomethacin is dose related over a range between 0.04 and 4 mg/kg body weight. Recovered day-1 DBM implants, transplanted into indomethacin pre- and posttreated syngeneic rats, formed bone at the same rate as controls did. However, recovered day-1 DBM implants lyophilized before transplantation showed decreased bone formation but significant dystrophic calcification as judged by a lower alkaline phosphatase activity and an elevated calcium content.

Effect of naproxen on cancellous bone in ovariectomized rats

Nonsteroidal anti-inflammatory drugs (NSAIDs) affect bone metabolism in vitro and in vivo. They delay but do not alter the outcome of healing processes in bone. In some bone loss models, they block bone resorption and slow the rate of loss. We studied the effect of naproxen, a potent NSAID, on cancellous bone of the proximal tibial metaphysis of 6-month-old adult female ovariectomized rats. Animals were ovariectomized, divided into groups, and fed standard diets differing only in naproxen content for 42 days. The rats of the groups ate 2.0, 5.5, 12.7, and 32 mg naproxen per kg body weight per day, respectively. Serum levels of naproxen were determined. Bone volume, mineralizing surface, osteoblast activity, osteoclast surface, and bone resorption rate were determined by bone histomorphometric techniques. The rats' dose-related serum naproxen levels ranged from 4 to 28 micrograms/ml. Naproxen inhibited up to 70% of the bone loss occurring after ovariectomy at a serum level of 4 micrograms/ml. We deduced that naproxen blocked bone resorption in ovariectomized rats by slowing osteoclast activity at all doses. In contrast, naproxen slowed bone formation only at serum levels greater than 20 micrograms/ml in ovariectomized rats. These findings may have clinical relevance in helping to prevent postmenopausal bone loss in women.

Indomethacin and bone trauma. Effects on remodeling of rabbit bone

The influence of indomethacin on remodeling activity in normal trabecular and cortical bone and its influence on cortical bone close to a midtibial drill hole, 2 mm in diameter were histomorphometrically evaluated. Eight rabbits were treated with indomethacin (12.5 mg/kg/day), and another 8 rabbits served as controls. After 3 days, the mean plasma indomethacin level was 542 ng/mL, resulting in an almost complete inhibition of prostaglandin synthesis as reflected by the serum levels. In the control rabbits the remodeling activity after 6 weeks was increased 1 mm away from the drill hole but not at 3 and 8 mm. In conclusion, indomethacin had no effect on the activated remodeling process in cortical bone neighboring a small drill hole or on remodeling in nontraumatized cortical and cancellous bone. This suggests that the inhibitory effect of indomethacin on the remodeling process following local trauma to bone depends on the extent of the trauma.

Indomethacin and bone remodeling. Effect on cortical bone after osteotomy in rabbits

Remodeling in cortical bone close to a plated tibial midshaft osteotomy was histomorphometrically evaluated in 32 rabbits. The animals were divided into two groups, one being treated with indomethacin (10 mg/kg per day) and the other receiving placebo. In the placebo-treated group, the remodeling activity was higher in the osteotomized leg compared with the intact leg. Two and 6 weeks after osteotomy, the number of resorptive and formative foci was reduced in the indomethacin-treated group compared with the placebo group. Porosity did not differ between the groups after 2 weeks; but after 6 weeks, it was reduced in the indomethacin-treated animals. Throughout the study, the bone formation rate did not differ between the two groups. This study demonstrates that indomethacin inhibits the remodeling of traumatized bone.

Uncertain effect of indomethacin on physeal growth injury. Experiments in rabbits

Growth arrest and shortening remain significant sequelae of growth-plate injuries. Nonsteroidal anti-inflammatory agents, known to inhibit callus and bone formation, may be useful to diminish callus-induced growth effects after epiphyseal fracture. In this study, we created a longitudinal osteotomy of the medial distal femoral condyle in 54 rabbits to model a Type IV epiphyseal fracture. We treated half with indomethacin and half with normal saline for 6 weeks. Nineteen animals of each group developed deformity, with indomethacin-treated animals averaging only slightly less angulation than the controls. However, the mean femoral shortening was less in the indomethacin-treated animals as compared with the controls.

A comparison of indomethacin and diclofenac in the inhibition of experimental heterotopic new bone formation

The effect of the two nonsteroidal antiinflammatory drugs Diclofenac and Indomethacin on the formation of heterotropic and orthotopic bone in rats was compared. Experimental heterotopic bone formation was induced by implanting demineralized bone matrix into the abdominal wall of rats. Indomethacin (3 mg/kg), Diclofenac (3, 6 or 12 mg/kg), or saline were given as daily subcutaneous injections. 3H-proline and 45Ca were given 24 h before the animals were killed. The net amount of bone formed by induction after three weeks was decreased by 15% by Indomethacin and Diclofenac in a dose of 3 mg/kg. The higher dose of 6 mg/kg of Diclofenac caused a higher degree of inhibition (30%), while 12 mg/kg produced toxic effects. Orthotopic bone was not affected by treatment with Indomethacin or Diclofenac. Although both drugs inhibit prostaglandin synthesis to a different degree, they exert similar effects on induced heterotopic bone, suggesting that this action is caused by an inhibition of the inflammatory response to trauma.

The influence of indomethacin on biomechanical and biochemical properties of the plantaris longus tendon in the rabbit

It has previously been reported that indomethacin inhibits fracture healing and heterotopic bone formation. Stimulated by these reports, we undertook the present investigation to study the influence of indomethacin on biomechanical and biochemical properties of the plantaris longus tendon in the rabbit. Sixty-eight New Zealand White rabbits were used for the experiment. Half of them were treated with indomethacin, 10 mg/kg orally a day, and the other half with placebo. After 4, 8, and 16 weeks of treatment biomechanical and biochemical variables were determined and compared between the two groups. After 16 weeks there was a significant increase in tensile strength in the group treated with indomethacin. There was no certain concomitant change in the total collagen content, the amounts of soluble and insoluble collagen, or the water content. Further investigations concerning the influence of indomethacin on tendon healing are indicated.

Indomethacin does not inhibit the anabolic effect of parathyroid hormone on the long bones of rats

Chronic administration of parathyroid hormone, hPTH 1-34, increased bone mass in normocalcemic, young rats. Since PTH can stimulate prostaglandin E2 (PGE2) production in bone in vitro, and since PGE2 can stimulate bone formation, the anabolic effect of PTH could be mediated by PGE2. To test this hypothesis, experiments were done to determine if indomethacin, which blocks endogenous PG production, would inhibit the anabolic response of bone to PTH. In the first experiment, male Sprague-Dawley rats, 70-100 g, in groups of five, were treated for 12 days with either hPTH 1-34, 8 micrograms/100g/day; PTH vehicle; indomethacin, 2 mg/kg/day; or a combination of PTH and indomethacin. In the second experiment, groups of 6 rats each were given vehicle or hPTH 1-34, 8 micrograms/100g/day, in combination with indomethacin, 0, 1, 2, or 4 mg/kg/day. Subcutaneous injections of PTH wee given once daily and indomethacin was given orally in divided doses, twice a day. Rats were killed on day 12 in both experiments; their sera were analyzed and the trabecular and cortical bone of distal femurs processed to determine calcium (Ca) and hydroxyproline content and dry weight. PTH and indomethacin had no significant effect on serum Ca, phosphate, alkaline phosphatase, urea nitrogen and creatinine, or systemic and long-bone linear growth. In rats treated with PTH alone or in combination with indomethacin, bone Ca of distal femurs increased by 28-44%; dry weight by 29-41%, and hydroxyproline by 17-45%. Indomethacin alone had no effect on bone growth.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of indomethacin on collagen synthesis during tendon healing in the rabbit

The influence of indomethacin on collagen synthesis in intact and healing plantaris longus tendons in the rabbit was investigated. Forty-four male New Zealand White rabbits were subjected to a standardized trauma (tenetomy + repair) on the left hindlimb. Half of the animals were subsequently treated with indomethacin, 10 mg/kg per day orally, and the other half with placebo. After 2 and 4 weeks the rabbits were injected intravenously with 3H-proline and killed 18 h later. Indomethacin affected the collagen metabolism differently depending on whether the tendons were involved in wound healing or not. In intact tendons the drug caused a small general inhibition of collagen synthesis. In the healing tendon there was a shift towards the synthesis of more insoluble collagen with little effect on the total synthesis. After 4 weeks there was also a slight but significant decrease in the amount of hydroxyproline in the most soluble collagen fraction from the tenotomized, indomethacin treated tendons.

Influences of inactivity and indomethacin on soleus phosphatidylethanolamine and size

Results of previous investigations indicate that muscular prostaglandins (PG) E2 and F2 alpha are biosynthesized during changes in muscular activity and stimulate protein degradation and synthesis, respectively. The results of the present investigation demonstrates a reduction by indomethacin of soleus hypertrophy, which occurred during a one week recovery period following rat hindlimb suspension. While this hypertrophic model evoked significant, rapid increases in soleus myosin and weight in control groups, continuous systemic release of indomethacin (3.5 mg/Kg/day) reduced the gain in soleus weight, Type I and II hypertrophy. Body weights of all groups were not significantly different. Additional analysis found a selective reduction in phosphatidylethanolamine (PE) during soleus atrophy and hypertrophy which were elicited by hindlimb suspension and recovery from suspension, respectively. Indomethacin enhanced PE recovery. Data from previous and present studies support a hypothesis that a change in soleus activity elicits PE catabolism, changes in cytosolic and muscular calcium, in calcium-dependent phospholipase activity, in PG biosynthesis, and in soleus size.

Effects of acetylsalicylic acid and naproxen on the mechanical properties of intact femora in rats

The influence of acetylsalicylic acid (ASA) and naproxen on growing bones was studied. Young male rats were used. The drugs were administered via gastric gavage twice a day for 9 or 18 days. Drug doses giving serum concentrations corresponding to ordinary anti-inflammatory steady-state levels in humans were used. There was a drug-related influence on the strength of the growing femur. After 9 days the ultimate bending moment of the distal femoral epiphyseal plate and ultimate torsional moment and stress of the femoral diaphysis increased by about 10% in the rats treated with 150 mg/kg/12 h of ASA as compared with controls. After 18 days there were no differences. The ultimate metaphyseal bending moment of the distal femur was not influenced after 9 days with this dose, but was reduced by about 10% compared with controls after 18 days. Doses of 100 mg/kg/12 h of ASA and 20 mg/kg/12 h of naproxen did not change the bone strength. The doses used were well tolerated and did not influence the bone growth or body weight of the rats. A naproxen dose of 40 mg/kg/12 h was lethal; rats that received this dose succumbed to jejunal perforations. The results indicate that ASA influences the remodeling of normally growing bones.

The osteo-inductive properties of bone matrix from rats pretreated with indomethacin

Decalcified bone matrix pieces were prepared from growing rats treated for 3 weeks with subcutaneous injections of indomethacin 2 mg/kg/day or saline, and implanted into growing rats. Of the 16 recipients with 'saline implants', 8 received saline and another 8 indomethacin 2 mg/kg/day in subcutaneous injections. In another 16 recipients with 'indomethacin implants', 8 received saline and 8 indomethacin. As in previous studies, it was found that indomethacin exerted a mild inhibition of new bone formation expressed as decreased amount of ash weight in implants. The amount of ash weight and 45Ca specific activity of implants in recipients with implants from indomethacin-treated donor animals was not altered. These findings indicate that indomethacin is unable to modify the osteo-inductive properties of bone matrix.

Lack of effect of indomethacin on mesenchymal limb-bud cells in vitro

Stimulated by reports of an inhibitory effect of non-steroid anti-inflammatory drugs on fracture healing and heterotopic bone formation in clinical and experimental studies, this investigation was performed to study the effect of indomethacin on chondrogenesis and mineralization in vitro by chicken mesenchymal limb-bud cells. Limb-bud cell cultures were treated with indomethacin and, in order to study a possible effect of metabolites, with serum from indomethacin-treated rats. No effects of the drug on chondrogenesis, as estimated by staining with alcian blue, could be detected. This was also the case when mineralization in the cultures induced by high phosphate concentrations was studied. It is concluded that indomethacin probably exerts its effect on bone metabolism through mechanisms other than modulation of cell differentiation or cell proliferation.

Experimentally induced heterotopic ossification in rats influenced by anti-inflammatory drugs

This paper reports the effects of peroral administration of the two non-steroid anti-inflammatory drugs ibuprofen and flubiprofen on orthotopic and induced heterotopic bone. The treatment induced no effects on the mineral or hydroxyproline contents of femur compared with a control group. Nor could any generalized toxic effects of the treatment be detected with respect to bodyweights or serum values of calcium, phosphate or albumin. Treatment with the drugs was commenced one week before initiating the heterotopic bone formation by implanting pieces of demineralized bone matrix in the abdominal muscle of growing rats. A significant decrease in specific amounts of calcium and phosphate was noted in the induced new-formed bone 4 weeks after implantation, whereas no such effect was apparent 2 weeks after implantation.

Inhibition of partial closure of epiphyseal plate in rabbits by indomethacin

The efficiency of indomethacin (10 mg/kg/day) in inhibiting recurrent partial closure of the epiphyseal plate was tested in rabbits. An epiphysiodesis was done laterally in the distal left femoral epiphyseal plate in 10 adolescent rabbits. This produced a valgus deformity in 14 of them. The bone bridge was then removed operatively and the rabbits were treated with either indomethacin or vehicle for 21 days postoperatively. Indomethacin plasma levels were about 180 ng/ml. The valgus deformity improved in indomethacin-treated rabbits, whereas it became worse in the controls (P = 0.004).