Pregablin

Pregabalin capsules are indicated for: Management of neuropathic pain associated with diabetic peripheral neuropathy Management of postherpetic neuralgia Adjunctive therapy for the treatment of partial-onset seizures in patients 1 month of age and older Management of fibromyalgia Management of neuropathic pain associated with spinal cord injury Pregabalin capsules are indicated for: Neuropathic pain associated with diabetic peripheral neuropathy (DPN) ( 1 ) Postherpetic neuralgia (PHN) ( 1 ) Adjunctive therapy for the treatment of partial-onset seizures in patients 1 month of age and older ( 1 ) Fibromyalgia ( 1 ) Neuropathic pain associated with spinal cord injury ( 1 )

Capsules: 25 mg, 50 mg, 75 mg, 100 mg, 150 mg, 200 mg, 225 mg, and 300 mg [see Description ( 11 ) and How Supplied/Storage and Handling ( 16 )] . Capsules: 25mg, 50 mg, 75 mg, 100 mg, 150 mg, 200 mg, 225 mg, and 300 mg. ( 3 )

Pregabalin capsules are contraindicated in patients with known hypersensitivity to pregabalin or any of its components. Angioedema and hypersensitivity reactions have occurred in patients receiving pregabalin therapy [see Warnings and Precautions ( 5.2 )]. Known hypersensitivity to pregabalin or any of its components. ( 4 )

Angioedema (e.g., swelling of the throat, head and neck) can occur, and may be associated with life-threatening respiratory compromise requiring emergency treatment. Discontinue pregabalin capsules immediately in these cases. ( 5.1 ) Hypersensitivity reactions (e.g. hives, dyspnea, and wheezing) can occur. Discontinue pregabalin capsules immediately in these patients. ( 5.2 ) Antiepileptic drugs, including pregabalin, the active ingredient in pregabalin capsules increase the risk of suicidal thoughts or behavior. ( 5.3 ) Abrupt or rapid discontinuation may increase the risk for seizures. Withdrawal symptoms or suicidal behavior and ideation have been observed after discontinuation. Taper pregabalin capsules gradually over a minimum of 1 week. ( 5.4 ) Respiratory depression: May occur with pregabalin capsules, when used with concomitant CNS depressants or in the setting of underlying respiratory impairment. Monitor patients and adjust dosage as appropriate. ( 5.5 ) Pregabalin capsules may cause dizziness and somnolence and impair patients’ ability to drive or operate machinery. ( 5.6 ) Pregabalin capsules may cause peripheral edema. Exercise caution when co-administering pregabalin capsules and thiazolidinedione antidiabetic agents. ( 5.7 )

5.1 Angioedema There have been postmarketing reports of angioedema in patients during initial and chronic treatment with pregabalin capsules. Specific symptoms included swelling of the face, mouth (tongue, lips, and gums), and neck (throat and larynx). There were reports of life-threatening angioedema with respiratory compromise requiring emergency treatment. Discontinue pregabalin capsules immediately in patients with these symptoms. Exercise caution when prescribing pregabalin capsules to patients who have had a previous episode of angioedema. In addition, patients who are taking other drugs associated with angioedema (e.g., angiotensin converting enzyme inhibitors [ACE-inhibitors]) may be at increased risk of developing angioedema.

5.2 Hypersensitivity There have been postmarketing reports of hypersensitivity in patients shortly after initiation of treatment with pregabalin capsules. Adverse reactions included skin redness, blisters, hives, rash, dyspnea, and wheezing. Discontinue pregabalin capsules immediately in patients with these symptoms .

5.3 Suicidal Behavior and Ideation Antiepileptic drugs (AEDs), including pregabalin, the active ingredient in pregabalin capsules, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Suicidal behavior and ideation have also been reported in patients after discontinuation of pregabalin [ see Warnings and Precautions ( 5.4 )]. Monitor patients treated with any AED for any indication for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. Pooled analyses of 199 placebo-controlled clinical trials (mono-and adjunctive therapy) of 11 different AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted Relative Risk 1.8, 95% CI:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 AED-treated patients was 0.43%, compared to 0.24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide. The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed. The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication. The risk did not vary substantially by age (5-100 years) in the clinical trials analyzed. Table 3 shows absolute and relative risk by indication for all evaluated AEDs. Table 3. Risk by Indication for Antiepileptic Drugs in the Pooled Analysis Indication Placebo Patients with Events Per 1000 Patients Drug Patients with Events Per 1000 Patients Relative Risk: Incidence of Events in Drug Patients/Incidence in Placebo Patients Risk Difference: Additional Drug Patients with Events Per 1000 Patients Epilepsy Psychiatric Other Total 1.0 5.7 1.0 2.4 3.4 8.5 1.8 4.3 3.5 1.5 1.9 1.8 2.4 2.9 0.9

1.9 The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications. Anyone considering prescribing pregabalin capsules or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated.

5.4 Increased Risk of Adverse Reactions with Abrupt or Rapid Discontinuation As with all antiepileptic drugs (AEDs), withdraw pregabalin capsules gradually to minimize the potential of increased seizure frequency in patients with seizure disorders. Following abrupt or rapid discontinuation of pregabalin capsules, some patients reported symptoms including insomnia, nausea, headache, anxiety, hyperhidrosis, and diarrhea [ see Adverse Reactions ( 6.2 ), Drug Abuse and Dependence ( 9.3 )]. Suicidal behavior and ideation have also been reported in patients after discontinuation of pregabalin [ see Warnings and Precautions ( 5.3 )]. If pregabalin capsules is discontinued, taper the drug gradually over a minimum of 1 week rather than discontinue the drug abruptly.

5.5 Respiratory Depression There is evidence from case reports, human studies, and animal studies associating pregabalin capsules with serious, life-threatening, or fatal respiratory depression when co-administered with central nervous system (CNS) depressants, including opioids, or in the setting of underlying respiratory impairment. When the decision is made to co-prescribe pregabalin capsules with another CNS depressant, particularly an opioid, or to prescribe pregabalin capsules to patients with underlying respiratory impairment, monitor patients for symptoms of respiratory depression and sedation, and consider initiating pregabalin capsules at a low dose. The management of respiratory depression may include close observation, supportive measures, and reduction or withdrawal of CNS depressants (including pregabalin capsules). There is more limited evidence from case reports, animal studies, and human studies associating pregabalin capsules with serious respiratory depression, without co-administered CNS depressants or without underlying respiratory impairment.

5.6 Dizziness and Somnolence Pregabalin capsules may cause dizziness and somnolence. Inform patients that pregabalin capsules -related dizziness and somnolence may impair their ability to perform tasks such as driving or operating machinery [ see Patient Counseling Information ( 17 )]. […]

The following serious adverse reactions are described elsewhere in the labeling: Angioedema [see Warnings and Precautions ( 5.1 )] Hypersensitivity [see Warnings and Precautions ( 5.2 )] Suicidal Behavior and Ideation [see Warnings and Precautions ( 5.3 )] Increased Risk of Adverse Reactions with Abrupt or Rapid Discontinuation [see Warnings and Precautions ( 5.4 )] Respiratory Depression [see Warnings and Precautions ( 5.5 )] Dizziness and Somnolence [see Warnings and Precautions ( 5.6 )] Peripheral Edema [see Warnings and Precautions ( 5.7 )] Weight Gain [see Warnings and Precautions ( 5.8 )] Tumorigenic Potential [see Warnings and Precautions ( 5.9 )] Ophthalmological Effects [see Warnings and Precautions ( 5.10 )] Creatine Kinase Elevations [see Warnings and Precautions ( 5.11 )] Decreased Platelet Count [see Warnings and Precautions ( 5.12 )] PR Interval Prolongation [see Warnings and Precautions ( 5.13 )] Most common adverse reactions (greater than or equal to 5% and twice placebo) in adults are dizziness, somnolence, dry mouth, edema, blurred vision, weight gain, and thinking abnormal (primarily difficulty with concentration/attention). ( 6.1 ) Most common adverse reactions (greater than or equal to 5% and twice placebo) in pediatric patients for the treatment of partial-onset seizures are increased weight and increased appetite. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Macleods Pharma USA, Inc. at 1-888-943-3210 or 1-855-926-3384. or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In all controlled and uncontrolled trials across various patient populations during the premarketing development of pregabalin capsules, more than 10,000 patients have received pregabalin capsules. Approximately 5000 patients were treated for 6 months or more, over 3100 patients were treated for 1 year or longer, and over 1400 patients were treated for at least 2 years. Adverse Reactions Most Commonly Leading to Discontinuation in All Premarketing Controlled Clinical Studies In premarketing controlled trials of all adult populations combined, 14% of patients treated with pregabalin capsules and 7% of patients treated with placebo discontinued prematurely due to adverse reactions. In the pregabalin capsules treatment group, the adverse reactions most frequently leading to discontinuation were dizziness (4%) and somnolence (4%). In the placebo group, 1% of patients withdrew due to dizziness and less than 1% withdrew due to somnolence. Other adverse reactions that led to discontinuation from controlled trials more frequently in the pregabalin capsules group compared to the placebo group were ataxia, confusion, asthenia, thinking abnormal, blurred vision, incoordination, and peripheral edema (1% each). Most Common Adverse Reactions in All Controlled Clinical Studies in Adults In premarketing controlled trials of all adult patient populations combined (including DPN, PHN, and adult patients with partial-onset seizures), dizziness, somnolence, dry mouth, edema, blurred vision, weight gain, and "thinking abnormal" (primarily difficulty with concentration/attention) were more commonly reported by subjects treated with pregabalin capsules than by subjects treated with placebo (greater than or equal to 5% and twice the rate of that seen in placebo). Controlled Studies with Neuropathic Pain Associated with Diabetic Peripheral Neuropathy Adverse Reactions Leading to Discontinuation In clinical trials in adults with neuropathic pain associated with diabetic peripheral neuropathy, 9% of patients treated with pregabalin capsules and 4% of patients treated with placebo discontinued prematurely due to adverse reactions. In the pregabalin capsules treatment group, the most common reasons for discontinuation due to adverse reactions were dizziness (3%) and somnolence (2%). In comparison, less than 1% of placebo patients withdrew due to dizziness and somnolence. Other reasons for discontinuation from the trials, occurring with greater frequency in the pregabalin capsules group than in the placebo group, were asthenia, confusion, and peripheral edema. Each of these events led to withdrawal in approximately 1% of patients. Most Common Adverse Reactions Table 4 lists all adverse reactions, regardless of causality, occurring in greater than or equal to 1% of patients with neuropathic pain associated with diabetic neuropathy in the combined pregabalin capsules group for which the incidence was greater in this combined pregabalin capsules group than in the placebo group. A majority of pregabalin-treated patients in clinical studies had adverse reactions with a maximum intensity of "mild" or "moderate". Table 4. Adverse Reaction Incidence in Controlled Trials in Neuropathic Pain Associated with Diabetic Peripheral Neuropathy Body system Preferred term 75 mg/day [N=77] % 150 mg/day [N=212] % 300 mg/day [N=321] % 600 mg/day [N=369] % All PGB* [N=979] % Placebo [N=459] % Body as a whole Asthenia 4 2 4 7 5 2 Accidental injury 5 2 2 6 4 3 Back pain 0 2 1 2 2 0 Chest pain 4 1 1 2 2 1 Face edema 0 1 1 2 1 0 Digestive system Dry mouth 3 2 5 7 5 1 Constipation 0 2 4 6 4 2 Flatulence 3 0 2 3 2 1 Metabolic and nutritional disorders Peripheral edema 4 6 9 12 9 2 Weight gain 0 4 4 6 4 0 Edema 0 2 4 2 2 0 Hypoglycemia 1 3 2 1 2 1 Nervous system Dizziness 8 9 23 29 21 5 Somnolence 4 6 13 16 12 3 Neuropathy 9 2 2 5 4 3 Ataxia 6 1 2 4 3 1 Vertigo 1 2 2 4 3 1 Confusion 0 1 2 3 2 1 Euphoria 0 0 3 2 2 0 Incoordination 1 0 2 2 2 0 Thinking abnormal† 1 0 1 3 2 0 Tremor 1 1 1 2 1 0 Abnormal gait 1 0 1 3 1 0 Amnesia 3 1 0 2 1 0 Nervousness 0 1 1 1 1 0 Respiratory system Dyspnea 3 0 2 2 2 1 Special senses Blurry vision‡ 3 1 3 6 4 2 Abnormal vision 1 0 1 1 1 0 * PGB: pregabalin † Thinking abnormal primarily consists of events related to difficulty with concentration/attention but also includes events related to cognition and language problems and slowed thinking. ‡ Investigator term; summary level term is amblyopia Controlled Studies in Postherpetic Neuralgia Adverse Reactions Leading to Discontinuation In clinical trials in adults with postherpetic neuralgia, 14% of patients treated with pregabalin capsules and 7% of patients treated with placebo discontinued prematurely due to adverse reactions. In the pregabalin capsules treatment group, the most common reasons for discontinuation due to adverse reactions were dizziness (4%) and somnolence (3%). In comparison, less than 1% of placebo patients withdrew due to dizziness and somnolence. Other reasons for discontinuation from the trials, occurring in greater frequency in the pregabalin capsules group than in the placebo group, were confusion (2%), as well as peripheral edema, asthenia, ataxia, and abnormal gait (1% each). Most Common Adverse Reactions Table 5 lists all adverse reactions, regardless of causality, occurring in greater than or equal to 1% of patients with neuropathic pain associated with postherpetic neuralgia in the combined pregabalin capsules group for which the incidence was greater in this combined pregabalin capsules group than in the placebo group. In addition, an event is included, even if the incidence in the all pregabalin capsules group is not greater than in the placebo group, if the incidence of the event in the 600 mg/day group is more than twice that in the placebo group. […]

Since pregabalin capsules are predominantly excreted unchanged in the urine, undergoes negligible metabolism in humans (less than 2% of a dose recovered in urine as metabolites), and does not bind to plasma proteins, its pharmacokinetics are unlikely to be affected by other agents through metabolic interactions or protein binding displacement. In vitro and in vivo studies showed that pregabalin capsules are unlikely to be involved in significant pharmacokinetic drug interactions. Specifically, there are no pharmacokinetic interactions between pregabalin and the following antiepileptic drugs: carbamazepine, valproic acid, lamotrigine, phenytoin, phenobarbital, and topiramate. Important pharmacokinetic interactions would also not be expected to occur between pregabalin capsules and commonly used antiepileptic drugs [see Clinical Pharmacology ( 12 )] . Pharmacodynamics Multiple oral doses of pregabalin capsules were co-administered with oxycodone, lorazepam, or ethanol. Although no pharmacokinetic interactions were seen, additive effects on cognitive and gross motor functioning were seen when pregabalin capsules was co-administered with these drugs. No clinically important effects on respiration were seen.

• Lactation: Breastfeeding is not recommended. ( 8.2 )

8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to pregabalin capsules during pregnancy. To provide information regarding the effects of in utero exposure to pregabalin capsules, physicians are advised to recommend that pregnant patients taking pregabalin capsules enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll free number 1-888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/. Risk Summary Observational studies on the use of pregabalin during pregnancy suggest a possible small increase in the rate of overall major birth defects, but there was no consistent or specific pattern of major birth defects identified (see Data). Available postmarketing data on miscarriage and other maternal, fetal, and long term developmental adverse effects were insufficient to identify risk associated with pregabalin. Postmarketing data suggest that extended gabapentinoid use with opioids close to delivery may increase the risk of neonatal withdrawal versus opioids alone (see Clinical Considerations). There are no comparative epidemiologic studies evaluating this association. Therefore, it is not known whether exposure to pregabalin alone late in pregnancy may cause withdrawal signs and symptoms. In animal reproduction studies, increased incidences of fetal structural abnormalities and other manifestations of developmental toxicity, including skeletal malformations, retarded ossification, and decreased fetal body weight were observed in the offspring of rats and rabbits given pregabalin orally during organogenesis, at doses that produced plasma pregabalin exposures (AUC) greater than or equal to 16 times human exposure at the maximum recommended dose (MRD) of 600 mg/day ( see Data ). In an animal development study, lethality, growth retardation, and nervous and reproductive system functional impairment were observed in the offspring of rats given pregabalin during gestation and lactation. The no-effect dose for developmental toxicity was approximately twice the human exposure at MRD. The estimated background risk of major birth defects and miscarriage for the indicated populations are unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. Clinical Considerations Fetal/Neonatal Adverse Reactions Neonatal withdrawal syndrome has been reported in newborns exposed to gabapentinoids in utero for an extended period of time when also exposed to opioids close to delivery. Neonatal withdrawal signs and symptoms reported have included tachypnea, vomiting, diarrhea, hypertonia, irritability, sneezing, poor feeding, hyperactivity, abnormal sleep pattern, and tremor. Reported signs and symptoms that may also be related to withdrawal include tongue thrusting, wandering eye movements while awake, back arching, and continuous extremity movements. Observe neonates exposed to pregabalin capsules and opioids for signs and symptoms of neonatal withdrawal and manage accordingly. Data Human Data One database study, which included over 2,700 pregnancies exposed to pregabalin (monotherapy) during the first trimester compared to 3,063,251 pregnancies unexposed to antiepileptics demonstrated prevalence ratios for major malformations overall of 1.14 (CI 95% 0.96-1.35) for pregabalin, 1.29 (CI 95% 1.01-1.65) for lamotrigine, 1.39 (CI 95% 1.07-1.82) for duloxetine, and 1.24 (CI 95% 1.00-1.54) for exposure to either lamotrigine or duloxetine. Important study limitations include uncertainty of whether women who filled a prescription took the medication and inability to adequately control for the underlying disease and other potential confounders. A published study included results from two separate databases. One database, which included 353 pregnancies exposed to pregabalin (monotherapy) during the first trimester compared to 368,489 pregnancies unexposed to antiepileptics, showed no increase in risk of major birth defects; adjusted relative risk 0.87 (CI 95% 0.53-1.42). The second database, which included 118 pregnancies exposed to pregabalin (monotherapy) during the first trimester compared to 380,347 pregnancies unexposed to antiepileptics, suggested a small increase in risk of major birth defects; adjusted relative risk 1.26 (CI 95% 0.64-2.49). The risk estimates crossed the null, and the study had limitations similar to the prior study. Other published epidemiologic studies reported inconsistent findings. No specific pattern of birth defects was identified across studies. All of the studies had limitations due to their retrospective design. Animal Data When pregnant rats were given pregabalin (500, 1250, or 2500 mg/kg) orally throughout the period of organogenesis, incidences of specific skull alterations attributed to abnormally advanced ossification (premature fusion of the jugal and nasal sutures) were increased at greater than or equal to 1250 mg/kg, and incidences of skeletal variations and retarded ossification were increased at all doses. Fetal body weights were decreased at the highest dose. The low dose in this study was associated with a plasma exposure (AUC) approximately 17 times human exposure at the MRD of 600 mg/day. A no-effect dose for rat embryo-fetal developmental toxicity was not established. When pregnant rabbits were given pregabalin capsules (250, 500, or 1250 mg/kg) orally throughout the period of organogenesis, decreased fetal body weight and increased incidences of skeletal malformations, visceral variations, and retarded ossification were observed at the highest dose. The no-effect dose for developmental toxicity in rabbits (500 mg/kg) was associated with a plasma exposure approximately 16 times human exposure at the MRD. In a study in which female rats were dosed with pregabalin capsules (50, 100, 250, 1250, or 2500 mg/kg) throughout gestation and lactation, offspring growth was reduced at greater than or equal to 100 mg/kg and offspring survival was decreased at greater than or equal to 250 mg/kg. The effect on offspring survival was pronounced at doses greater than or equal to 1250 mg/kg, with 100% mortality in high-dose litters. When offspring were tested as adults, neurobehavioral abnormalities (decreased auditory startle responding) were observed at greater than or equal to 250 mg/kg and reproductive impairment (decreased fertility and litter size) was seen at 1250 mg/kg. The no-effect dose for pre-and postnatal developmental toxicity in rats (50 mg/kg) produced a plasma exposure approximately 2 times human exposure at the MRD. In the prenatal-postnatal study in rats, pregabalin prolonged gestation and induced dystocia at exposures greater than or equal to 50 times the mean human exposure (AUC (0–24) of 123 μg∙hr/mL) at the MRD.

8.2 Lactation Risk Summary Small amounts of pregabalin have been detected in the milk of lactating women. A pharmacokinetic study in lactating women detected pregabalin in breast milk at average steady state concentrations approximately 76% of those in maternal plasma. The estimated average daily infant dose of pregabalin from breast milk (assuming mean milk consumption of 150 mL/kg/day) was 0.31 mg/kg/day, which on a mg/kg basis would be approximately 7% of the maternal dose ( see Data ). The study did not evaluate the effects of pregabalin capsules on milk production or the effects of pregabalin capsules on the breastfed infant. Based on animal studies, there is a potential risk of tumorigenicity with pregabalin exposure via breast milk to the breastfed infant [see Nonclinical Toxicology ( 13.1 )]. […]

Pregabalin binds with high affinity to the alpha2-delta site (an auxiliary subunit of voltage-gated calcium channels) in central nervous system tissues. Although the mechanism of action of pregabalin has not been fully elucidated, results with genetically modified mice and with compounds structurally related to pregabalin (such as gabapentin) suggest that binding to the alpha2-delta subunit may be involved in pregabalin's anti-nociceptive and antiseizure effects in animals. In animal models of nerve damage, pregabalin has been shown to reduce calcium-dependent release of pro-nociceptive neurotransmitters in the spinal cord, possibly by disrupting alpha2-delta containing-calcium channel trafficking and/or reducing calcium currents. Evidence from other animal models of nerve damage and persistent pain suggest the anti-nociceptive activities of pregabalin may also be mediated through interactions with descending noradrenergic and serotonergic pathways originating from the brainstem that modulate pain transmission in the spinal cord. While pregabalin is a structural derivative of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), it does not bind directly to GABA A , GABA B , or benzodiazepine receptors, does not augment GABAA responses in cultured neurons, does not alter rat brain GABA concentration or have acute effects on GABA uptake or degradation. However, in cultured neurons prolonged application of pregabalin increases the density of GABA transporter protein and increases the rate of functional GABA transport. Pregabalin does not block sodium channels, is not active at opiate receptors, and does not alter cyclooxygenase enzyme activity. It is inactive at serotonin and dopamine receptors and does not inhibit dopamine, serotonin, or noradrenaline reuptake.