Pregabalin for Pain Management

Pregabalin induced balance disorder, asthenia, edema, and constipation in an elderly adult: A case report

BACKGROUND

Pregabalin is widely used to treat neuropathic pain associated with postherpetic neuralgia. To our knowledge, this is the first report on simultaneously occurring dose-related adverse drug reactions (ADRs) of balance disorder, asthenia, peripheral edema, and constipation in an elderly patient after pregabalin.

CASE SUMMARY

A 76-year-old female with a history of postherpetic neuralgia was prescribed pregabalin (300 mg daily). After taking pregabalin for 7 d, the patient developed balance disorder, weakness, peripheral pitting edema (2+), and constipation. On days 8-14, the pregabalin dose was reduced to 150 mg/d based on creatinine clearance. The patient’s peripheral edema improved significantly with the disappearance of all other adverse symptoms. On day 15, the pregabalin dose was increased to 225 mg/d to relieve pain. Unfortunately, the symptoms mentioned earlier gradually reappeared after 1 wk of pregabalin treatment. However, the complaints were not as severe as when taking 300 mg/d pregabalin. The patient consulted her pharmacist by telephone and was advised to reduce the dose of pregabalin to 150 mg/d and add acetaminophen (0.5 g, q6h) to relieve pain. The patient’s ADRs gradually improved over the following week.

CONCLUSION

Older patients should be prescribed a lower initial dose of pregabalin. The dose should be titrated to the maximum tolerable dose to avoid dose-limiting ADR. Dose reduction and the addition of acetaminophen may help limit ADR and improve pain control.

Comparative Study of the Neurotoxic Effects of Pregabalin Versus Tramadol in Rats

In Egypt, both pregabalin and tramadol misuse increased in the last decade. Although many studies have confirmed the neurotoxic effects of tramadol, those of pregabalin are understudied. The aim of the study is to evaluate the neurotoxic effects of pregabalin compared with tramadol. Thirty male albino rats were included in this experimental study, and they were randomly allocated into three equal groups: group I (normal saline), group II (tramadol misuse), and group III (pregabalin misuse). All rats received the commenced drugs for 1 month. Open field tests were performed on the day of scarification, and after that, cortical samples were taken for immunohistochemical analysis and quantification of dopamine receptors' gene expression. The drug misuse groups showed a significant decrease in weight gain at the end of the study. Open field testing showed the upper hand of controls regarding all of the tested parameters. Tramadol has a more negative impact on the locomotor parameters compared with pregabalin. Both drugs induced relatively low dopamine-1 receptor (D1Rs) expression to dopamine-2 receptors (D2Rs), mimicking the schizophrenia model. Both tramadol and pregabalin were associated with neurotoxic effects in male albino rats. These effects were less noticed with pregabalin. It is suggested that long-term abuse may end in psychosis.

Efficacy and Safety of Pregabalin for Muscle Cramps in Liver Cirrhosis: A Double-Blind Randomized Controlled Trial

BACKGROUND

Muscle cramp is possibly related to peripheral nerve hyperexcitability (PNH), and one of the most debilitating symptoms frequently encountered in patients with liver cirrhosis. We investigated whether pregabalin, a gamma-aminobutyric acid analogue, can suppress neuronal excitability and reduce muscle cramps in cirrhotic patients.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial in which study participants with cirrhosis from a single tertiary center were enrolled. Primary endpoint was the relative change in cramp frequency from the run-in to standard dose treatment phase (4 weeks per each). Secondary endpoints included the responder rate, and the changes in cramp frequency during sleep, pain intensity, health-related quality of life (Liver Disease Quality of Life Instrument, Short Form-36) and electrophysiological measures of PNH.

RESULTS

This study was terminated early because of insufficient accrual. 80% (n = 56) of the target number of participants (n = 70) were randomized to pregabalin (n = 29) or placebo (n = 27). Median baseline frequency of muscle cramps (interquartile range) was 5.8 (3.5-10) per week in the pregabalin group and 6.5 (4.0-10) in the placebo group (P = 0.970). The primary analysis showed a significant reduction in cramp frequency with pregabalin compared to placebo (-36% vs. 4.5% for the percentage change, P = 0.010). Secondary outcomes did not differ significantly between the two groups. Adverse effects with pregabalin were mainly dizziness and lethargy.

CONCLUSION

With multiple problems emerging from premature termination in mind, the results suggested an acceptable safety profile and favorable effect of pregabalin in reducing muscle cramps compared to placebo in cirrhotic patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01271660.

Effectiveness of Pregabalin for Treatment of Burning Mouth Syndrome

Treatment of burning mouth syndrome (BMS) is challenging because there is no consensus regarding pharmalogical or nonpharmalogical therapies. The use of anticonvulsants is controversial. We present nine patients BMS who respond to pregabalin. They were diagnosed secondary BMS except two. Etiologic regulations were made firstly in patients with secondary BMS but symptoms did not decrease. We preferred pregabalin in all patients and got good results. Furthermore the addition of pregabalin to the treatment of two patients who did not respond adequately to duloxetine provided good results. We are only aware that pregabalin may reduce symptoms as a result of case reports. We believe that the diagnosis of pathologic etiology with appropriate diagnostic tests will result in better outcomes in treatment.

Effectiveness of preanesthetic administration of gabapentin on sedative action during intravenous sedation with propofol

PURPOSE

There are no sufficient evidences for the sedative effect of gabapentin during anesthesia, especially intravenous sedation (IVS). The purpose of this study was to evaluate the sedative effect of gabapentin as preanesthetic medication during the IVS with propofol.

METHODS

10 volunteer subjects joined this study. They underwent propofol IVS three times on separate days. On the first day, the IVS without gabapentin was performed as a control. On the second and the third day, gabapentin 200 mg and 400 mg were administered before the IVS, respectively. The target blood concentration (C_T) of propofol was gradually increased, and the bispectral index (BIS) value and Ramsay sedation score (RSS) were evaluated at each propofol C_T. Postanesthetic complications and influences on vital signs were also evaluated.

RESULTS

Compared to the control group, the propofol C_Ts in the gabapentin 400 mg group significantly reduced at the BIS values of 60 and 70 (p = 0.031 and p = 0.043, respectively), and at RSS 3, 4, 5 and 6 (p = 0.040, p = 0.004, p = 0.001 and p = 0.004, respectively). There was no significant difference in propofol C_Ts between the control group and the gabapentin 200 mg group. There were no abnormality and no deterioration in circulation and respiration in all groups. There were no significant increases in complications with the administration of gabapentin.

CONCLUSION

The oral administration of 400 mg dose of gabapentin reduced the propofol C_Ts for achieving an adequate sedation level on IVS.

The effect of pregabalin and duloxetine treatment on quality of life of breast cancer patients with taxane-induced sensory neuropathy: A randomized clinical trial

Background:

The primary side effect of adjuvant chemotherapy with taxanes is the taxane-induced peripheral neuropathy (TIPN), which may have substantial negative impacts on patients’ quality of life (QOL). We investigated the effect of pregabalin and duloxetine on QOL of breast cancer patients who experienced TIPN.

Materials and Methods:

This was a randomized, double-blind clinical trial conducted at a chemotherapy center of Mazandaran University of Medical Sciences, Sari, Iran. Breast cancer patients 18 or more years old were included if they received paclitaxel or docetaxel and experienced neuropathy grade one or higher; and neuropathic pain score of four or more. Patients were treated with pregabalin or duloxetine until 6 weeks. Assessment of sensory neuropathy and QOL was performed at baseline, and 6 weeks after the initiation of the treatment.

Results:

At baseline, the mean score of global health status/QOL scale for pregabalin and duloxetine groups were 61 (standard deviation [SD]; 5.11) and 60.28 (SD; 5.44), respectively (P = 0.54). After 6 weeks, both interventions were associated with improvement of global QOL compared to baseline. The global health status/QOL score was not different between two groups after 6 weeks. While the emotional functioning was improved more favorably with duloxetine (P < 0.001); pregabalin was associated with more improvement in insomnia and pain scores (P = 0.05 and P < 0.001, respectively).

Conclusion:

Pregabalin as well as duloxetine improve the global QOL of breast cancer patients with TIPN. Different effects of treatments on subscale of QLQ-C30 could help clinicians to select the appropriate agent individually.

Pregabalin Did Not Improve Pain Management After Spinal Fusions

BACKGROUND

The treatment of postoperative pain is a challenge after posterior spinal fusions. Pain management using predominantly opioids is often associated with multiple adverse effects, while multimodal postoperative analgesia may provide adequate pain relief with fewer opioid side effects.

QUESTIONS/PURPOSES

The purpose of this review is to determine whether addition of 150 mg pregabalin daily would reduce narcotic requirements and improve outcomes after posterior lumbar fusion (PLF).

METHODS

The method used is a randomized, controlled trial of elective PLF patients who received pregabalin or placebo. With institutional review board (IRB) approval, 86 patients undergoing elective posterior lumbar fusion, ASA I-III, were randomized to receive either a placebo or pregabalin after obtaining written informed consent. Both arms, i.e., placebo and pregabalin, consisted of 43 patients each.The 86 patients for elective PLF were randomly assigned to receive 150 mg of pregabalin 1 h before surgery and then 150 mg daily, or a placebo tablet. All patients received a similar general anesthetic and in the post-anesthesia care unit (PACU), started on intravenous (IV) patient-controlled analgesia (PCA) of hydromorphone (0.2 mg/ml). Postoperative pain was assessed daily until discharge using a Numerical Rating Scale (NRS) at rest and with physical therapy (PT). Patients were also assessed twice daily for level of sedation and nausea and/or vomiting and expected PT milestones. All narcotics (IV, oral) were documented.

RESULTS

Demographics and operative time between groups were similar. PCA hydromorphone administration and oral narcotic intake were not statistically different between the two groups. However, an increased incidence of nausea and vomiting in the placebo group reached statistical significance (p < 0.05). In addition, there was no statistical difference between groups with respect to achieving PT milestones and hospital discharge day.

CONCLUSION

After PLF, patients receiving pregabalin 150 mg/day did not have reduced IV narcotic usage, improved PT milestones, or reduced length of hospital stay. We were unable to demonstrate an analgesic advantage to prescribing pregabalin to patients undergoing lumbar spinal fusions.

Pregabalin-induced self-harm behavior

Antiepileptic Drugs (AEDs) such as lamotrigine, gabapentin, and oxcarbazepine may have the potential to increase the risk of self-harm or suicidal behavior. We report a case of pregabalin-induced self-inflicted multiple injuries on forearm after its continuous use. This is an interesting adverse drug reaction (ADR) that is rare, unusual, and potentially serious.

Pregabalin- and topiramate-mediated regulation of cognitive and motor impulsivity in DBA/2 mice

BACKGROUND AND PURPOSE

Impulsivity is a core symptom in many neuropsychiatric disorders. The main objective of this study was to evaluate the effects of topiramate and pregabalin on the modulation of different impulsivity dimensions in DBA/2 mice.

EXPERIMENTAL APPROACH

The effects of acute and chronic administration of pregabalin (10, 20 and 40 mg·kg(-1) ) and topiramate (12.5, 25 and 50 mg·kg(-1) ) were evaluated in the light-dark box (LDB), hole board test (HBT) and delayed reinforcement task (DRT). α(2A) -Adrenoceptor, D(2) -receptor and TH gene expression were evaluated by real-time PCR in the prefrontal cortex (PFC), accumbens (ACC) and ventral tegmental area (VTA), respectively.

KEY RESULTS

Acute pregabalin administration showed a clear anxiolytic-like effect (LDB) but did not modify novelty-seeking behaviour (HBT). In contrast, topiramate produced an anxiolytic effect only at the highest dose, whereas it reduced novelty seeking at all doses tested. In the DRT, acute pregabalin had no effect, whereas topiramate only reduced motor impulsivity. Chronically, pregabalin significantly increased motor impulsivity and topiramate diminished cognitive impulsivity. Pregabalin decreased α(2A) -adrenoceptor and D(2) -receptor gene expression in the PFC and ACC, respectively, and increased TH in the VTA. In contrast, chronic administration of topiramate increased α(2A) -adrenoceptor and D(2) -receptor gene expression in the PFC and ACC, respectively, and also increased TH in the VTA.

CONCLUSIONS AND IMPLICATIONS

These results suggest that the usefulness of pregabalin in impulsivity-related disorders is related to its anxiolytic properties, whereas topiramate modulates impulsivity. These differences could be linked to their opposite effects on α(2A) -adrenoceptor and D(2) -receptor gene expression in the PFC and ACC, respectively.

Current considerations for the treatment of severe chronic pain: the potential for tapentadol

Studies suggest that around 20% of adults in Europe experience chronic pain, which not only has a considerable impact on their quality of life but also imposes a substantial economic burden on society. More than one-third of these people feel that their pain is inadequately managed. A range of analgesic drugs is currently available, but recent guidelines recommend that NSAIDs and COX-2 inhibitors should be prescribed cautiously. Although the short-term efficacy of opioids is good, adverse events are common and doses are frequently limited by tolerability problems. There is a perceived need for improved pharmacological treatment options. Currently, many treatment decisions are based solely on pain intensity. However, chronic pain is multifactorial and this apaproach ignores the fact that different causative mechanisms may be involved. The presence of more than one causative mechanism means that chronic pain can seldom be controlled by a single agent. Therefore, combining drugs with different analgesic actions increases the probability of interrupting the pain signal, but is often associated with an increased risk of drug/drug interactions, low compliance and increased side effects. Tapentadol combines μ-opioid receptor agonism and noradrenaline reuptake inhibition in a single molecule, with both mechanisms contributing to its analgesic effects. Preclinical testing has shown that μ-opioid agonism is primarily responsible for analgesia in acute pain, whereas noradrenaline reuptake inhibition is more important in chronic pain. In clinical trials in patients with chronic pain, the efficacy of tapentadol was similar to that of oxycodone, but it produced significantly fewer gastrointestinal side-effects and treatment discontinuations. Pain relief remained stable throughout a 1-year safety study. Thus, tapentadol could possibly overcome some of the limitations of currently available analgesics for the treatment of chronic pain.

Efficacy and tolerability of pregabalin versus topiramate in the prophylaxis of chronic daily headache with analgesic overuse: an open-label prospective study

OBJECTIVES

Medication-overuse headache is one of the most disabling headaches. Antiepileptic drugs have been considered a promising strategy as prophylactic treatment in these patients, even if their use often has been limited by low tolerability or safety. The objective of this study was to evaluate the efficacy and safety of pregabalin compared with topiramate for the prophylaxis of chronic daily headache with medication overuse using an open-label prospective study.

METHODS

After a 2-month baseline period (T0), 100 consecutive patients with medication overuse headache were assigned to receive 150 mg/d pregabalin or 100 mg/d topiramate. After a titration period of 4 weeks, a follow-up visit was scheduled every 2 months (T1 and T2) to evaluate headache frequency, the amount of rescue medication intake, and disability.

RESULTS

Of the 46 pregabalin-treated patients, the mean monthly headache frequency significantly decreased from 21.8 ± 4.8 (T0) to 5.1 ± 3.8 (T2), and the monthly number of days with medication intake decreased from 15.1 ± 4.8 (T0) to 2.9 ± 1.9 (T2). Similarly, of the 42 topiramate-treated patients, the mean monthly headache frequency decreased from 21.8 ± 4.9 (T0) to 5.3 ± 3.5 (T2), and the mean monthly number of days with medication intake decreased from 15.1 ± 3.7 (T0) to 2.6 ± 1.5 (T2). A significant improvement of disability score was reported in both groups.

CONCLUSIONS

Similar to topiramate, pregabalin seems to be an effective and well-tolerated preventive therapy in chronic headache and a new option in the management of withdrawal from abused drugs in patients with analgesic overuse, a difficult-to-treat population.

Efficacy and tolerability of pregabalin using a flexible, optimized dose schedule in Korean patients with peripheral neuropathic pain: a 10-week, randomized, double-blind, placebo-controlled, multicenter study

BACKGROUND

Clinical trials from various countries have reported the efficacy of pregabalin for reducing peripheral neuropathic pain.

OBJECTIVE

This study assessed the efficacy and tolerability of pregabalin in Korean patients with neuropathic pain.

METHODS

This was a Phase III, 10-week, randomized, double-blind, placebo-controlled, multicenter study. Patients aged ≥ 18 years with neuropathic pain (diabetic peripheral neuropathy, postherpetic neuralgia, or posttraumatic neuropathic pain) were enrolled and randomly assigned (2:1 ratio) to pregabalin (150-600 mg/d) or matching placebo. Randomization was performed using a proprietary telerandomization system. The primary end point was the difference in week 8 least squares (LS) mean Daily Pain Rating Scale (DPRS) score (rated once daily from 0 ["no pain"] to 10 ["worst possible pain"]) between pregabalin and placebo, calculated using the average of the last 7 available DPRS scores. Secondary efficacy measures included the following: the proportion of responders whose DPRS scores were reduced by ≥ 30% or ≥ 50% versus baseline, the Daily Sleep Interference Scale (DSIS; 11-point scale, scored daily), the Euro Quality of Life assessment (EQ-5D; 2 items scored separately), the Medical Outcomes Study (MOS) Sleep Scale (12 items each scored separately), the Hospital Anxiety and Depression Scale (HADS; 2 items scored from 0 to 21), the Patient Global Impression of Change (PGIC) and the Clinical Global Impression of Change (CGIC; each scored on a 7-point scale), and tolerability assessments. Adverse events and vital signs were monitored throughout the study with laboratory measurements, physical examinations, neurologic examinations, and 12-lead ECG tests. Data were analyzed using ANCOVA or Cochran-Mantel-Haenszel test, and P < 0.05 was considered statistically significant.

RESULTS

The treatment groups (n = 162 pregabalin; n = 78 placebo) were well matched at baseline (pregabalin: 51.2% [83/162] female; mean [SD] age, 59.7 [10.8] years; weight, 63.6 [9.3] kg; placebo: 59.0% [46/78] female; mean age, 61.3 [12.9] years; weight, 62.0 [9.5] kg). All patients were Korean. The mean doses at end point were 480 mg/d for pregabalin and 513 mg/d for the placebo equivalent. Most patients received concomitant drug treatments during the study: 79.6% (129/162) in the pregabalin group and 92.3% (72/78) in the placebo group. The mean DPRS score at end point was significantly lower in the pregabalin group than in the placebo group (LS mean difference, -0.50; 95% CI, -1.00 to 0.00; P = 0.049). In total, 26.1% (42/161) of pregabalin-treated patients reported ≥ 50% improvement in mean DPRS scores from baseline, compared with 14.3% (11/77) for placebo (P = 0.041 between groups). The LS mean change in the DSIS from baseline to end point favored pregabalin (-0.51; 95% CI, -0.96 to -0.07; P = 0.024). Significant improvements were also recorded for overall MOS sleep interference score (difference in LS means, -0.65; P = 0.018) and HADS anxiety subscale score (-0.85; P = 0.038). Other secondary assessments (eg, EQ-5D, HADS depression subscale, PGIC, and CGIC) did not reach significance. A higher proportion of patients reported treatment-related adverse events with pregabalin (43.8% [71/162]) than with placebo (29.5% [23/78]). Dizziness (21.0% [34/162]), somnolence (13.6% [22/162]), face edema (6.2% [10/162]), peripheral edema (6.2% [10/162]), and weight gain (5.6% [9/162]) were the most commonly reported adverse events in the pregabalin group.

CONCLUSION

Flexible-dose pregabalin (150-600 mg/d for 8 weeks) was associated with a significant, although modest, reduction in mean DPRS score; an improvement in anxiety and subjective sleep; and generally good tolerability compared with placebo in these Korean patients with neuropathic pain due to diabetic peripheral neuropathy, postherpetic neuralgia, or posttraumatic neuropathic pain.

The determination and application of fixed-dose analgesic combinations for treating multimodal pain

When the pathophysiology of a medical condition is multimodal, ie, related to multiple physiological causes or mediated by multiple pathways, the optimal strategy can be to use a drug or a combination of drugs that contribute multiple mechanisms to the therapeutic endpoint. In such situations, a rational multimodal approach can also result in the fewest adverse effects. We discuss the quantitative analysis of multimodal action using the treatment of pain as a practical example and give examples of its application to some widely used analgesic drugs.

PERSPECTIVE

This article reviews the medical relevance of the quantitative evaluation of drug combinations, using pain and combinations of analgesics as specific examples. Such measure can help clinicians who seek to maximize therapeutic effect while simultaneously minimizing adverse effects.

Selective inhibitory effects of pregabalin on peripheral C but not A-delta fibers mediated nociception in intact and spinalized rats

Effects of pregabalin (PGB, 20-80 mg/kg i.v. injection) on spinally-organized nociception were investigated in isoflurane-anesthetized intact and spinalized rats. Responses of single deep spinal dorsal horn (DH) (laminae IV-V) nociceptive-specific (NS) neurons receiving peripheral inputs from A-delta and C fibers to repetitive electrical stimulation (intensity: 3-5 mA; frequency: 1 Hz; pulse duration: 1 ms), mechanical/heat stimulation were recorded extracellularly during physiological condition and s.c. bee venom (BV) induced inflammation. PGB significantly inhibited C-fiber mediated spinal NS neurons' late responses including phenomena of wind-up (temporal summation) and after-discharge. However, the antinociceptive effects of PGB on nociception were not observed until 30 min after its administration. In contrast, no significant inhibitory effect of PGB on A-delta fiber mediated early responses was observed during the experiments. Compared with intact rats, the inhibitory effects of PGB upon nociception vanished in the spinalized animals. This suggests that PGB-induced selective antinociceptive effect on C-fiber mediated nociception is mainly central effects involving supraspinal centers via descending inhibitory controls. Furthermore, pre-treatment, but not post-treatment, with PGB (80 mg/kg) markedly inhibited s.c. BV elicited spontaneous neuronal responses, and noxious mechanical/heat stimuli evoked hyperactivities of spinal NS neurons, indicating that PGB has efficacy of pre-emptive analgesia on pathological pain associated with central sensitization.

Gabapentin for decerebrate rigidity: a case report

A 48-year-old woman suddenly lost consciousness as a result of a right rostral pontine tegmentum haemorrhage. The patient presented with decerebrate rigidity (DR) and regained full consciousness 5 days after the initial onset. The patient was given gabapentin 1200 mg/day nasogastrically and her DR significantly improved, although other antiepileptic drugs such as phenytoin and carbamazepine were given in larger dosages to decrease muscle hypertonicity. The patients' preserved consciousness and motor-evoked potentials to transcranial magnetic stimulation indicated a derangement of the extrapyramidal tracts with preservation of the pyramidal tracts. This case report discusses the possible mechanisms of action of gabapentin in DR.