Combination pharmacotherapy for management of chronic pain: From bench to bedside
Departments of Anaesthesiology and Perioperative Medicine and Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada. Electronic address: . The Lancet Neurology
(Impact Factor: 21.9).
09/2013; 12(11). DOI: 10.1016/S1474-4422(13)70193-5
Chronic pain, a frequently neglected problem, is treated with different classes of drugs. Current agents are limited by incomplete efficacy and dose-limiting side-effects. Knowledge of pain processing implicates multiple concurrent mechanisms of nociceptive transmission and modulation. Thus, synergistic interactions of drug combinations might provide superior analgesia and fewer side-effects than monotherapy by targeting of multiple mechanisms. Several trials in neuropathic pain, fibromyalgia, arthritis, and other disorders have assessed various two-drug combinations containing antidepressants, anticonvulsants, non-steroidal anti-inflammatories, opioids, and other agents. In some trials, combined treatment showed superiority over monotherapy, but in others improved benefit or tolerability was not seen. Escalating efforts to develop novel analgesics that surpass the efficacy of current treatments have not yet been successful; therefore, combination therapy remains an important beneficial strategy. Methodological improvements in future translational research efforts are needed to maximise the potential of combination pharmacotherapy for pain.
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- "Painful diabetic neuropathy (PDN) is one of the most common causes of chronic pain. Chronic pain affects 30% of the United States (US) population and has high treatment costs, estimated approximately to be 650 billion dollars . Chronic pain treatment requires a multidisciplinary intervention and, sometimes, use of multimodal treatments . This situation has required using combination drugs as a treatment alternative, towards improving the patient progno- sis. "
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ABSTRACT: . Painful diabetic neuropathy (PDN) is a prevalent and impairing disorder. The objective of this study was to show the efficacy and safety of gabapentin (GBP) plus complex B vitamins: thiamine (B1) and cyanocobalamine (B12) compared to pregabalin in patients with moderate to severe intensity PDN.
. Multicenter, randomized, blind study. Two hundred and seventy patients were evaluated, 147 with GBP/B1/B12 and 123 with PGB, with a 7/10 pain intensity on the Visual Analog Scale (VAS). Five visits (12 weeks) were scheduled. The GBP/B1 (100 mg)/B12 (20 mg) group started with 300 mg at visit 1 to 3600 mg at visit 5. The PGB group started with 75 mg/d at visit 1 to 600 mg/d at visit 5. Different safety and efficacy scales were applied, as well as adverse event assessment.
. Both drugs showed reduction of pain intensity, without significant statistical difference (
). In the GBP/B1/B12 group, an improvement of at least 30% on VAS correlated to a 900 mg/d dose, compared with PGB 300 mg/d. Likewise, occurrence of vertigo was lower in the GBP/B1-B12 group, with a significant statistical difference,
. Our study shows that GPB/B1-B12 combination is as effective as PGB. Nonetheless, pain intensity reduction is achieved with 50% of the minimum required gabapentin dose alone (800 to 1600 mg/d) in classic NDD trials. Less vertigo and dizziness occurrence was also observed in the GBP/B1/B12 group. This trial is registered with ClinicalTrials.gov
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- "While monotherapies are effective in some cases, combining more than one drug in a treatment regimen, called combination therapy, has shown to be equally if not more effective under some pain circumstances . The goal of combination therapy is to enable the use of smaller doses of each drug in combination to achieve the same or better analgesic effects while circumventing unwanted side effects that may result from higher doses of a single drug (Gilron et al. 2013). The imidazoline I 2 receptor is a novel target for analgesics (Li et al. 2014; Li and Zhang 2011). "
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Recent evidence suggests that imidazoline I2 receptor ligands are suitable for combination therapy with opioids. Quantitative analysis of I2 receptor ligands combined with non-opioid drugs is necessary for the justification of alternative pain therapies.
This study systematically examined the antihyperalgesic and response rate-suppressing effects of selective I2 receptor ligands (2-BFI and phenyzoline) alone and in combination with acetaminophen.
Von Frey and Hargreaves tests were used to examine the antihyperalgesic effects of drugs in complete Freund’s adjuvant (CFA)-induced inflammatory pain in rats. Food-reinforced schedule-controlled responding was used to assess the rate-suppressing effects of study drugs. Dose-addition and isobolographic analyses were used to assess drug-drug interactions for all assays.
2-BFI (3.2–17.8 mg/kg, i.p.), phenyzoline (17.8–100 mg/kg, i.p.), and acetaminophen (56–178 mg/kg, i.p.) all dose-dependently produced significant antinociceptive effects. When studied as combinations, 2-BFI and acetaminophen produced infra-additive to additive interactions while phenyzoline and acetaminophen produced additive to supra-additive interactions. The same drug combinations suppressed response rate in a supra-additive manner.
Quantitative analysis of the antihyperalgesic and response rate-suppressing effects suggests that I2 receptor ligands are not well suited to combination therapy with acetaminophen.
Available from: Jun-Xu Li
- "A promising strategy is combination therapy, which requires combining two or more drugs as a pharmacotherapy and has been successfully practiced for treating various diseases including pain (Orrù et al. 2014; Smith 2008). The overall aim of combination therapy is to increase the analgesic effectiveness of analgesics such as opioids and/or reduce unwanted effects as smaller doses of individual drugs may be needed (Smith 2008; Gilron et al. 2013). "
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ABSTRACT: Emerging preclinical evidence suggests that imidazoline I2 receptor ligands may be effective analgesics. Quantitative analysis of the combined I2 receptor ligands and opioids is needed for the justification of combination therapy.
This study systematically examined the anti-hyperalgesic and response rate-suppressing effects of selective I2 receptor ligands (2-BFI and phenyzoline) alone and in combination with oxycodone in rats.
Von Frey filament test was used to examine the anti-hyperalgesic effects of drugs in a rat model of complete Freund's adjuvant (CFA)-induced inflammatory pain. Schedule-controlled responding was used to assess the rate-altering effects of study drugs. Duration of actions of individual drugs (2-BFI, phenyzoline, and oxycodone) alone or in combination was studied. Dose-addition analysis was employed to assess the anti-hyperalgesic interactions between drugs.
Oxycodone (0.1-3.2 mg/kg, i.p.), 2-BFI (1-17.8 mg/kg, i.p.), and phenyzoline (17.8-56 mg/kg, i.p.) all dose-dependently produced significant antinociceptive effects. When studied as combinations, 2-BFI and oxycodone produced additive interactions while phenyzoline and oxycodone produced supra-additive interactions under all fixed ratios. The same drug combinations did not alter or significantly reduced the operant responding depending on the ratios of the drug combinations.
Quantitative analysis of the anti-hyperalgesic effects of I2 receptor ligands strongly supports the therapeutic potential of I2 receptor ligands against inflammatory pain. In addition, the data reveal that phenyzoline is superior to the prototypic I2 receptor ligand 2-BFI for the management of pain and warrants further consideration as a novel analgesic.
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