The FDA has approved Combogesic IV (Hikma), an IV solution containing acetaminophen and ibuprofen, to treat mild to moderate pain (alone) or moderate to severe pain (in combination with an opioid) in adults when IV analgesia is considered clinically necessary. Single-drug IV solutions containing ibuprofen (Caldolor) and acetaminophen have been available in the US for years.

A new CDC guideline for prescribing opioids for pain recently became available. Nonopioid drugs for pain were reviewed in a previous issue.

View the Comparison Table: Some Oral/Transdermal Opioid Analgesics

The FDA has approved Seglentis (Esteve/Kowa), an oral combination of tramadol hydrochloride, a weak opioid agonist and weak serotonin and norepinephrine reuptake inhibitor (SNRI), and celecoxib, a COX-2 selective nonsteroidal anti-inflammatory drug (NSAID), for use in adults with acute pain that is severe enough to require an opioid and for which alternative treatment options are inadequate.

Nonopioid drugs can be used in the treatment of many nociceptive and neuropathic pain conditions. For severe pain, especially severe chronic cancer pain, use of opioids may be necessary. Noninvasive nonpharmacologic treatments, including physical and psychological therapies, have been shown to improve pain and function in patients with some common chronic pain conditions and are unlikely to cause serious harms. A multimodal approach to analgesic therapy can increase pain control while reducing opioid use and adverse effects.

View the Comparison Table: Some Nonopioid Analgesics for Pain

Atogepant (Qulipta – Abbvie), an oral small-molecule calcitonin gene-related peptide (CGRP) receptor antagonist ("gepant"), has been approved by the FDA for prevention of episodic migraine in adults. It is the second oral CGRP receptor antagonist to be approved in the US for this indication; the first was rimegepant (Nurtec ODT), which is also approved for acute treatment of migraine. Parenteral CGRP monoclonal antibodies are approved for prevention of migraine (see Table 3).

The opioid agonist tramadol is now available in an oral solution (Qdolo – Athena Bioscience) for management of pain severe enough to require an opioid and for which alternative treatment options are inadequate. Tramadol has been available for years in immediate-release tablets and capsules, extended-release capsules (Ultram, and others), and in a fixed-dose combination tablet with acetaminophen (Ultracet, and generics).

Oliceridine (Olinvyk - Trevena), an IV opioid agonist, has been approved by the FDA for management of acute pain severe enough to require an opioid and for which alternative treatment options are inadequate.

A fixed-dose combination of orphenadrine citrate, aspirin, and caffeine (Orphengesic Forte – Galt; previously available as Norgesic Forte) has been approved as a prescription drug by the FDA for treatment of mild to moderate pain caused by acute musculoskeletal disorders. Single-ingredient generic orphenadrine citrate is available by prescription in oral and injectable formulations and has been used for years as an adjunct for treatment of acute musculoskeletal pain. Orphengesic Forte is being marketed as a non-opioid alternative for pain relief.

The FDA has approved Anjeso (Baudax Bio), an IV formulation of the nonsteroidal anti-inflammatory drug (NSAID) meloxicam, for once-daily treatment of moderate to severe pain in adults. Oral meloxicam (Mobic, and others), which is only indicated for treatment of chronic pain associated with osteoarthritis or rheumatoid arthritis, has been available for 20 years. IV formulations of ketorolac, ibuprofen (Caldolor), and acetaminophen (Ofirmev) are also available for treatment of pain.

Cannabis (marijuana) contains more than 60 pharmacologically active cannabinoids; delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are the best known. THC is the main psychoactive constituent of cannabis. CBD, unlike THC, does not produce intoxication or euphoria.

The FDA has approved Apadaz (KemPharm), a short-acting, fixed-dose combination of benzhydrocodone and acetaminophen, for short-term management (≤14 days) of acute pain severe enough to require an opioid and for which alternative treatment options are inadequate. Benzhydrocodone is a prodrug of hydrocodone. Fixed-dose combinations of short-acting hydrocodone and acetaminophen or ibuprofen have been available for years and are the most abused opioid products in the US. Apadaz was developed under the presumption that inclusion of the inactive prodrug would reduce the potential for abuse of the combination by non-oral routes such as smoking, snorting, or injection, but the FDA did not approve Apadaz as an abuse-deterrent formulation.

The FDA has approved Roxybond (Daiichi Sankyo), an short-acting (SA) oxycodone formulation with abuse-deterrent properties, for treatment of pain requiring management with an opioid. Roxybond is the first SA opioid to be approved as an abuse-deterrent product. Oxaydo, another IR oxycodone formulation, has properties that discourage its intranasal and intravenous use, but is not considered an abuse-deterrent product by the FDA. Use of opioids for treatment of pain was reviewed in a recent issue.

Use of nonopioid drugs for pain was reviewed in a previous issue. For many types of moderate to severe acute pain, acetaminophen and/or an NSAID may be as effective as an opioid. Immediate-release formulations of full opioid agonists should generally be used for acute pain that is severe enough to require treatment with an opioid. Use of extended-release or long-acting opioid formulations initially and treatment durations >1 week have been associated with an increased risk of unintended long-term use.

View the Comparison Table: Some Oral/Topical Opioid Analgesics

Nonopioid drugs can be used in the treatment of many nociceptive and neuropathic pain conditions. Use of opioids for pain will be reviewed in a future issue.

View the Comparison Table: Some Nonopioid Analgesics for Pain

Treatment of epilepsy should begin with a single antiepileptic drug (AED), increasing its dosage gradually until seizures are controlled or adverse effects become intolerable. If seizures persist, specialists generally recommend trying at least one and sometimes a second alternative drug as monotherapy before considering use of two drugs concurrently. When used for the appropriate seizure type, AEDs are roughly equivalent in efficacy. Drug choice is usually based on factors such as ease of use, adverse effects, drug interactions, presence of comorbidities, and cost.

The FDA has issued new warnings about the use of the opioid analgesics codeine and tramadol in children, particularly those <12 years old, and in breastfeeding women due to concerns about the risk of respiratory depression and death. The FDA previously issued warnings about these drugs in 2013 and 2015.

The results of a clinical trial (PRECISION) comparing the cardiovascular safety of the COX-2 selective NSAID celecoxib (Celebrex, and generics) with that of ibuprofen and naproxen, which are nonselective, have been described in the lay press in terms that may overestimate the safety of celecoxib.

The FDA has approved Xtampza ER (Collegium), a new extended-release, abuse-deterrent capsule formulation of oxycodone, for management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate.

Belbuca (Endo), a buccal formulation of the partial opioid agonist buprenorphine, has been approved by the FDA for management of pain severe enough to require daily, around-the-clock, long-term opioid treatment. Buprenorphine is also available as a transdermal patch (Butrans) and in a parenteral formulation (Buprenex, and generics) for treatment of pain. A sublingual formulation of buprenorphine and buccal and sublingual formulations containing buprenorphine and the opioid antagonist naloxone are approved for use as alternatives to methadone for treatment of opioid dependence.

The FDA has approved Vivlodex (Iroko), a low-dose formulation of the nonsteroidal anti-inflammatory drug meloxicam (Mobic, and generics), for management of osteoarthritis pain. According to the manufacturer, the new formulation aligns with stronger FDA warnings about the cardiovascular risks of NSAIDs and the recommendation to use the lowest possible doses of these drugs.

A patient-controlled fentanyl iontophoretic transdermal system (Ionsys – The Medicines Company) is now available for short-term management of acute postoperative pain in adults requiring opioid analgesia in the hospital. Before using Ionsys, patients must be titrated to a comfortable level of analgesia with another opioid formulation.

The FDA has approved a second extended-release (ER) formulation of the oral opioid agonist hydrocodone (Hysingla ER – Purdue) for management of pain severe enough to require continuous long-term therapy and for which alternative treatment options are inadequate. Hysingla ER tablets have abuse-deterrent properties to discourage their misuse.

The Drug Enforcement Administration (DEA) has reclassified all hydrocodone combination products as schedule II controlled substances; they were previously classified as schedule III. Hydrocodone alone (Zohydro ER) is already a schedule II controlled substance.

The FDA has approved a fixed-dose extended-release formulation of oxycodone and acetaminophen (Xartemis XR – Mallinckrodt) for oral treatment of acute pain severe enough to require an opioid. Oxycodone is available in the US as a single entity in oral immediate-release (Oxecta, and others) and extendedrelease (OxyContin) formulations. Immediate-release oxycodone is also available in combination with aspirin (Percodan, and others), acetaminophen (Percocet, and others), or ibuprofen (see Table 1).

The same pharmaceutical company (Iroko) that recently marketed low-dose diclofenac (Zorvolex) for treatment of mild to moderate acute pain1 has now received approval from the FDA to market a low-dose oral formulation of indomethacin (Tivorbex) for the same indication. Tivorbex is available in 20- and 40-mg capsules; conventional immediate-release indomethacin capsules contain 25 mg and 50 mg of the drug.

The rationale for this new product is the same as the one offered for Zorvolex: the drug is formulated as submicron particles that increase surface area, leading to faster dissolution and absorption. According to the package insert, the time to reach peak serum concentrations (Tmax) was 1.67 hours with a 40-mg capsule of Tivorbex, compared to 2.02 hours with a standard 50-mg capsule of indomethacin.

The problem with Tivorbex is the same as the problem with Zorvolex: there are no studies comparing its efficacy to that of standard doses of indomethacin or to any other NSAID. In addition, indomethacin is generally considered one of the most potent NSAIDs and one of those most likely to cause GI bleeding, increase cardiovascular risk, and damage the kidneys. There is no good reason to use indomethacin in any dosage for treatment of mild to moderate pain.

1. Low-dose diclofenac (Zorvolex) for pain. Med Lett Drugs Ther 2014; 56:19.

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The FDA has approved Zorvolex (Iroko), a low-dose oral formulation of the relatively COX-2 selective NSAID diclofenac, for treatment of mild-to-moderate acute pain in adults.

Pain can be acute or chronic. The two major types of chronic pain are nociceptive pain and neuropathic pain. Nociceptive pain can be treated with nonopioid analgesics or opioids. Neuropathic pain is less responsive to opioids and is often treated with adjuvant drugs such as antidepressants and antiepileptics. Combining different types of analgesics may provide an additive analgesic effect without increasing adverse effects.

The FDA has approved a sublingual spray formulation of fentanyl (Subsys – Insys) for management of breakthrough pain in adult cancer patients who are receiving and are tolerant to opioid therapy (taking ≥60 mg/day of oral morphine or the equivalent). Fentanyl is already available in the US for intravenous, intrathecal, epidural, transdermal and transmucosal use.

Recent reports indicate that intramuscular (IM) injection of the nonsteroidal anti-inflammatory drug (NSAID) ketorolac (Toradol, and others), sometimes directly into injured muscles, has become a common practice in US locker rooms.

The FDA has approved a new formulation (Exparel – Pacira) of the local anesthetic bupivacaine (Marcaine, and others) for use in the management of postsurgical pain in adults.

The FDA has approved a new tablet formulation of immediate-release (IR) oxycodone (Oxecta – King) for management of acute and chronic moderate to severe pain.

Oxecta uses a tamper-resistant technology designed to deter oxycodone abuse by injection or nasal snorting. Dissolving the crushed tablet in water or alcohol converts it into a viscous gel mixture, making it difficult to inject. Crushing the tablet and inhaling it through the nose causes burning and irritation. Whether the new formulation will actually prevent abuse of the drug has not been established. Oxecta is classified as a Schedule II controlled substance.1

In patients who have not been receiving opioid analgesics, the recommended starting dosage of Oxecta is 5 to 15 mg every 4 to 6 hours as needed for pain. Oxycodone has no analgesic ceiling, but dosage is usually limited by its adverse effects. Use of similar abuse-resistant tablets has been associated with reports of difficulty swallowing the tablets.2 Oxecta tablets should be swallowed whole and taken with enough water to ensure complete swallowing.

1. Drugs for pain.Treat Guidel Med Lett 2010; 8:25.

2. US Food and Drug Administration. Center for Drug Evaluation and Research. Oxecta (oxycodone HCl) tablets. Summary Review. Available at www.accessdata.fda.gov/scripts/cder/drugsatfda. Acccessed February 24, 2012.

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For patients with radicular pain unresponsive to conservative treatment after 1-2 months and no progressive neurologic deficit, epidural corticosteroid injections are often tried before surgical intervention.

An intranasal formulation of ketorolac tromethamine (Sprix – Lutipold) has been approved by the FDA for short-term (up to 5 days) treatment of moderate to moderately severe pain in adults. It is the first nonsteroidal anti-inflammatory drug (NSAID) to become available in an intranasal formulation. Ketorolac tromethamine is also available in oral, ophthalmic and injectable formulations.

The FDA has approved a nasal spray formulation of fentanyl (Lazanda – Archimedes) for management of breakthrough pain in adult cancer patients who are already receiving and are tolerant to opioid therapy. Fentanyl is already available in the US for intravenous, intrathecal, epidural, transdermal and oral transmucosal use.

A new once-daily formulation of gabapentin (Gralise – Depomed) has been approved by the FDA for treatment of postherpetic neuralgia (PHN). Immediate-release (IR) gabapentin (Neurontin, and others), which has been available in the US since 1994, is also approved for this indication, but is taken three times a day. Extended-release gabapentin enacarbil (Horizant) was recently approved by the FDA for treatment of restless legs syndrome.

The FDA has approved the opioid agonist hydromorphone in a once-daily extended-release (ER) oral tablet formulation (Exalgo – Covidien) for the management of moderate to severe pain in opioid-tolerant patients requiring continuous, long-term therapy. Another hydromorphone ER formulation (Palladone – Purdue) was available previously, but was withdrawn from the market because taking it with alcohol could interfere with the extended-release mechanism and lead to rapid release of potentially lethal amounts of the drug ("dose-dumping").

The FDA has approved a topical 8% patch formulation of capsaicin (Qutenza – NeurogesX), available only by prescription, for local treatment of postherpetic neuralgia. Postherpetic neuralgia occurs after herpes zoster in about one third of patients ≥60 years old and can persist for months or even years.

The FDA has approved the marketing of fentanyl sublingual tablets (Abstral – ProStrakan) for treatment of breakthrough pain in adult cancer patients who are already receiving and are tolerant to opioid therapy. It is the fourth transmucosal formulation of fentanyl to become available in the US for this indication.1-3

The manufacturer recommends an initial dose of 100 mcg, a maximum of 2 doses per breakthrough pain episode, and use for no more than 4 breakthrough pain episodes per day. As with all formulations of fentanyl, strong inhibitors of CYP3A4 such as clarithromycin (Biaxin, and others) or itraconazole (Sporanox, and others) can increase serum concentrations of the drug to levels that can cause respiratory depression even in opioid- tolerant patients. A single dose of any formulation of transmucosal fentanyl could be fatal for a child.

1. Fentanyl buccal tablet (Fentora) for breakthrough pain. Med Lett Drugs Ther 2007; 49:78.

2. Drugs for pain. Treat Guidel Med Lett 2010; 8:25.

3. Fentanyl buccal soluble film (Onsolis) for breakthrough cancer pain. Med Lett Drugs Ther 2010; 52:30.

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Previously approved by the FDA for treatment of depression, general anxiety disorder, diabetic peripheral neuropathic pain and fibromyalgia, duloxetine (Cymbalta – Lilly) has now also been approved for treatment of chronic musculoskeletal pain.

The FDA has approved the partial opioid agonist buprenorphine in a transdermal formulation (Butrans – Purdue) for treatment of moderate to severe chronic pain. Buprenorphine has been available in the US for years in parenteral formulations for pain and in sublingual tablets for opioid dependence.1 Transdermal buprenorphine has been available in Europe for several years.2

A recent article in Circulation reported that acetaminophen (Tylenol, and others; paracetamol outside the US) increased blood pressure in patients with coronary artery disease. This conclusion was based on a randomized, placebo-controlled crossover trial in 33 patients; acetaminophen 1 g three times daily for 2 weeks was associated with statistically significant increases in blood pressure of 2.9 mmHg systolic and 2.2 mmHg diastolic.1

NSAIDs can increase blood pressure; the mechanism is thought to be inhibition of cyclooxygenase leading to decreased renal prostaglandin activity. Acetaminophen also inhibits cyclooxygenase (primarily COX-2) and decreases prostaglandin activity.2

The small increases in blood pressure reported with acetaminophen would probably be inconsequential in low-risk patients, but might be a concern for those with cardiovascular disease. Like most drugs, acetaminophen should be used in the lowest effective doses for the shortest possible time. Mild to moderate pain due to osteoarthritis or headache generally responds to a dose of 650 mg.3

1. I Sudano et al. Acetaminophen increases blood pressure in patients with coronary artery disease. Circulation 2010; 122:1789.

2. B Hinz et al. Acetaminophen (paracetamol) is a selective cyclooxygenase-2 inhibitor in man. FASEB J 2008; 22:383.

3. Drugs for pain. Treat Guidel Med Lett 2010; 8:25.

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Fentanyl buccal soluble film (Onsolis – Meda) has been approved by the FDA for treatment of breakthrough pain in adult cancer patients who are already taking and are tolerant to around-the-clock opioid therapy. It is designated as a Schedule II controlled substance Two other oral transmucosal formulations of fentanyl are already available for this indication.

Pain can be acute or chronic. Chronic pain has been broadly classified into two types: nociceptive and neuropathic. Nociceptive pain can be treated with nonopioid analgesics or opioids. Neuropathic pain is less responsive to opioids; adjuvant medicines such as antidepressants and anticonvulsants are often used to treat neuropathic pain. Combining different types of analgesics may provide an additive analgesic effect without increasing adverse effects.

The FDA has approved an agonist/antagonist combination of morphine and naltrexone (Embeda – King) for treatment of chronic moderate to severe pain requiring around-the-clock analgesia for an extended period of time. The addition of naltrexone is intended to prevent abuse of morphine.

Fourteen states in the US - Alaska, California, Colorado, Hawaii, Maine, Michigan, Montana, Nevada, New Jersey, New Mexico, Oregon, Rhode Island, Vermont and Washington - now permit, or soon will permit, some medical use of marijuana (Cannabis sativa). In some states, licensed facilities dispense botanical cannabis by prescription. In others, limited self-cultivation is permitted for medical use.

An intraveneous (IV) formulation of ibuprofen (Caldolor - Cumberland) was recently approved by the FDA for use in adults. It can be administered alone for treatment of mild to moderate pain or as an adjunct to opioid analgesics for moderate to severe pain. It is also approved for reduction of fever.

The FDA has approved tapentadol hydrochloride (Nucynta - Ortho-McNeil Janssen) for oral treatment of moderate to severe acute pain in patients ≥18 years old. It has been classified as a Schedule II controlled substance

Transdermal fentanyl (Duragesic, and others) offers a convenient delivery system for patients with chronic pain1 but it has some drawbacks. One is that exposing the patch to heat, either from an external source, increased exertion or possibly high fever, could increase release of the drug, which might lead to an overdose and fatal respiratory depression.2 A recent article in the NY Times about this problem may have aroused the concerns of some patients using the patches.3

First approved for marketing by the FDA in 19914, transdermal fentanyl provides continuous delivery of the drug for about 3 days. After application of the patch, a depot of fentanyl forms in the upper layers of the skin. Serum concentrations of the drug increase gradually, reaching a peak (Cmax) in 24-72 hours. According to a pharmacokinetic model mentioned in the labeling, an increase in body temperature to 40°C (104°F) could increase fentanyl serum concentrations by 33%. Local application of heat near or on a fentanyl transdermal patch also increases systemic absorption; in one study, heating the patch during the first 4 hours after application increased maximum serum concentrations nearly three-fold.5 Unintentional increases in systemic fentanyl absorption caused by a heating pad, a warming blanket used during surgery and strenuous exertion have led to respiratory depression in 3 patients.6 No reports of clinical overdosage caused by fever have been published.

Serious adverse events may require removal of the patch and administration of an opioid antagonist such as naloxone (Narcan, and others). Monitoring for hypoventilation or cognitive impairment for at least 24 hours is recommended after removing the patch because fentanyl concentrations decrease slowly (50% decrease in about 17 hours) due to continued systemic absorption from the intracutaneous reservoir.

1. Drugs for pain. Treat Guidel Med Lett 2007; 5:23.
2. FDA Alert 7/15/2005; Update 12/21/2007. Information for healthcare professionals: Fentanyl transdermal system (marketed as Duragesic and generics). Available at www.fda.gov/cder/drug/InfoSheets/HCP/fentanyl_2007HCP.htm. Accessed July 27, 2009.
3. T Brown. Doctors and nurses, still learning. New York Times, April 29, 2009. Available at NYTimes.com. Accessed July 29, 2009.
4. Transdermal fentanyl. Med Lett Drugs Ther 1992; 34:97.
5. MA Ashburn et al. The pharmacokinetics of transdermal fentanyl delivered with and without controlled heat. J Pain 2003; 4:291.
6. KA Carter. Heat-associated increase in transdermal fentanyl absorption. Am J Health Syst Pharm 2003; 60:191.

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Concerns have surfaced again at the FDA and in the media about the safety of acetaminophen and the multiplicity of products on the market in the US that contain various amounts of it.

Milnacipran (Savella - Forest), an oral selective serotonin and norepinephrine reuptake inhibitor (SNRI), is the third drug approved by the FDA for management of fibromyalgia. The 2 others are pregabalin, a gammaaminobutyric acid (GABA) analog also approved for treatment of diabetic neuropathy, post-herpetic neuralgia and epilepsy, and duloxetine, an SNRI also approved for treatment of depression, diabetic neuropathy and generalized anxiety disorder.

Spinal decompression machines offer a motorized form of mechanical traction. These devices, which are widely advertised to the public as a noninvasive alternative to surgery, are claimed to relieve low back pain by decompressing discs, improving the flow of nutrients into the disc and rehydrating dried-out discs. Devices cleared by the FDA based on substantial similarity to previously approved power traction devices include the Accu- Spina System, DRS System, DRX9000, Lordex Traction Unit, Spinal Health Elite, SpineMED Decompression Table, SpineRx-LDM and VAX-D Therapeutic Table.

Some drugs for treatment of migraine attacks are listed in table 2 on page 18. Drugs for prevention of migraine are listed in table 3 on page 20. Treatment of migraine in the emergency room, which may involve use of intravenous drugs, is not included here.

Diclofenac epolamine patch 1.3% (Flector Patch - Alpharma), a topical formulation of the nonsteroidal anti-inflammatory drug (NSAID) diclofenac, has been approved by the FDA for topical treatment of acute pain due to minor strains, sprains and contusions. It is the first topical NSAID patch approved in the US. A diclofenac patch has been used in Europe since 1993. Diclofenac sodium (Voltaren, and others) is available in the US as an oral tablet, in a 1% gel for treatment of osteoarthritis (to be reviewed in a future issue), in a 3% gel (Solaraze) for treatment of actinic keratoses, and in an ophthalmic formulation.

An extended-release formulation of the centrally-acting muscle relaxant cyclobenzaprine (Amrix - Cephalon) has been approved by the FDA for treatment of muscle spasms. Immediate-release (IR) cyclobenzaprine (Flexeril, and others) has been available since 1977.

The FDA has approved a transmucosal tablet formulation of fentanyl citrate (Fentora - Cephalon) for management of breakthrough pain in opioid-tolerant patients with cancer. An oral transmucosal fentanyl lozenge on a stick (Actiq, and others) is also available for this indication, and is widely used off-label for chronic, non-cancer pain as well.

Pain can be acute or chronic. Chronic pain has been broadly classified into two types: nociceptive and neuropathic. Nociceptive pain is generally treated with nonopioid analgesics and opioids. Antidepressants and anticonvulsants have been used to treat neuropathic pain. Combining two different types of analgesics may nprovide an additive analgesic effect without increasing adverse effects.

Oxymorphone hydrochloride, a semi-synthetic opioid agonist, has been available for many years in the US as Numorphan (Endo) for parenteral use and as a rectal suppository. Now it has been approved by the FDA for oral administration as an immediate-release (IR) tablet (Opana) for treatment of moderate to severe acute pain, and as an extended-release tablet (Opana ER) for treatment of moderate to severe pain in patients requiring continuous opioid treatment for an extended period of time.

A fixed-dose combination of oxycodone 5 mg and ibuprofen 400 mg (Combunox - Forest Laboratories) is now available and is being heavily advertised for short-term treatment of moderate to severe acute pain.

The FDA has approved ziconotide (Prialt - Elan) intrathecal infusion for management of severe chronic pain in patients who are intolerant of or refractory to other treatments. Ziconotide is a synthetic neuronal N-type calcium channel blocker. It is intended for use with a programmable implanted microinfusion device, but an external microinfusion device can be used temporarily.

Duloxetine hydrochloride (Cymbalta - Lilly), a selective serotonin and norepinephrine reuptake inhibitor (SNRI) available for treatment of depression, has also been approved by the FDA for treatment of neuropathic pain associated with diabetic peripheral neuropathy (DPN). Duloxetine is one of two drugs approved specifically for management of neuropathic pain due to diabetes; the other, pregabalin (Lyrica - Pfizer), will be marketed soon and will be reviewed in the next issue of The Medical Letter.

Ropinirole (Requip - GlaxoSmithKline), a dopamine agonist already available for treatment of Parkinson's disease, is now the first drug approved by the FDA for treatment of moderate to severe restless legs syndrome (RLS).

The Medical Letter review of Palladone (hydromorphone HCl) extended-release capsules (March 14, 2005) warned that a lethal dose could be released if the new formulation was taken with alcohol. Because of that risk, the FDA asked the manufacturer (Purdue) to withdraw the drug from the market (FDA News. July 13, 2005; FDC Reports – “The Pink Sheet” July 18, 2005; 67:3).

A once-daily extended-release (ER) oral formulation of the opioid analgesic hydromorphone hydrochloride (Palladone - Purdue Pharma) has been approved by the FDA for treatment of opioid-tolerant patients with persistent moderate to severe pain. Hydromorphone HCl, a semisynthetic congener of morphine and active metabolite of hydrocodone that has been used since the 1920s, is also available in immediate-release oral, injectable and suppository forms (Dilaudid, and others).

In our January 17 issue, a short article on NSAID alternatives mentioned that tramadol (Ultram, and others), a weak opioid analgesic, could be helpful for some patients. A few readers have commented that we should have said something about its drawbacks. The need for slow titration in dosage limits the drug's use for treatment of acute pain. Seizures have been reported with tramadol; patients taking an antidepressant or an antipsychotic drug may be at increased risk. Tramadol is not a controlled substance, but psychological and physical dependence have occurred.

Patients taking nonsteroidal anti-inflammatory drugs (NSAIDs) may be asking their health care providers if they should continue, and some may be asking for alternatives. For most patients taking nonspecific NSAIDs, it would be reasonable to continue. For those who are taking the COX-2 selective celecoxib (Celebrex) because they cannot tolerate the gastrointestinal (GI) effects of nonspecific NSAIDs, it seems reasonable to continue at doses no higher than 100 mg b.i.d. or 200 mg once daily; at these dosages cardiovascular risk has been no higher than with placebo. All NSAIDs, including COX-2 inhibitors, can decrease renal blood flow and cause fluid retention, hypertension and renal failure, especially in the elderly and in patients who take diuretics. The unpublished study that led to an FDA alert on an increased cardiovascular risk with naproxen (Naprosyn, and others) was conducted in patients older than 70. See NSAID addendum

With the removal of Vioxx from the market and concerns about cardiovascular toxicity with other selective COX-2 inhibitors, patients are looking for safe alternatives, and manufacturers of other drugs are looking for additional market share. The COX-2 inhibitors first became popular because they have less upper GI toxicity than older less selective NSAIDs, at least in the short term, in patients not taking aspirin.

Duloxetine hydrochloride (Cymbalta - Lilly), a selective serotonin and norepinephrine reuptake inhibitor (SNRI), has been approved by the FDA for treatment of major depressive disorder in adults, and more recently for diabetic peripheral neuropathy as well. The Medical Letter will review its role in diabetic neuropathy in a future issue.

Drugs for treatment of migraine attacks are listed in the table on page 64. All of the oral drugs are most effective if taken early in an attack when the pain is mild (H Christoph-Diener et al, Neurology 2004; 63:520). Drugs for prevention of migraine are listed in the table on page 65. Treatment of migraine in the emergency room, which may involve use of intravenous drugs, is not included here.

Gabapentin (Neurontin - Pfizer), which has been available in the US since 1994, is approved by the FDA only for treatment of partial epilepsy and postherpetic neuralgia, but is widely used off-label for a number of other indications, especially neuropathic pain syndromes. According to one report, among Medicaid recipients in Florida receiving gabapentin, 71% of prescriptions were for chronic pain and 8% for seizures and neuralgia ("The Pink Sheet" February 2, 2004; 66:30).

Spinal manipulation has been used to treat not only back and neck pain, but also many other conditions. A recent commentary questioned its safety.

Valdecoxib (Bextra - Pharmacia/Pfizer), a selective cyclooxygenase (COX-2) inhibitor similar to celecoxib (Celebrex) and rofecoxib (Vioxx), was recently approved by the FDA for treatment of osteoarthritis, rheumatoid arthritis and primary dysmenorrhea.

Rofecoxib, a selective COX-2 inhibitor, has been approved by the FDA for treatment of osteoarthritis, acute pain and menstrual pain.

Three types of analgesic drugs are available: first, non-opioids, including aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen; second, opioids; and third, some drugs not usually thought of as analgesics, which act as adjuvants when given with NSAIDs or opioids, or have analgesic activity of their own in some types of pain.

Bromfenac sodium (Duract - Wyeth-Ayerst), a nonsteroidal anti-inflammatory drug (NSAID), has been approved by the US Food and Drug Administration (FDA) and is being heavily advertised as an alternative to narcotics for short-term treatment of pain.

Tramadol hydrochloride (Ultram - Ortho-McNeil), a centrally-acting analgesic marketed in Germany since 1977, was recently approved by the US Food and Drug Administration for oral treatment of moderate to moderately severe pain. Despite some opioid activity, tramadol has not been scheduled as a controlled substance.

Butorphanol tartrate, a synthetic opioid agonist-antagonist analgesic previously available for injection, is now being marketed as a nasal spray (Stadol-NS - Mead Johnson). The spray was approved by the US Food and Drug Administration (FDA) for any type of pain for which an opioid analgesic is appropriate, but the manufacturer is emphasizing use for treatment of migraine headache and postoperative pain. Drugs for pain were reviewed in the Medical Letter, volume 35, page 1, January 8, 1993.

Three types of analgesic drugs are available in the USA: first, aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen; second, opioids; and third, drugs not usually thought of as analgesics, which act as adjuvants when given with NSAIDs or opioids, or have analgesic activity of their own in some types of pain. (American Pain Society, Principles of analgesic Use, 3rd ed, Skokie, illinois: American pain society, 1992).

Fentanyl, a synthetic opioid previously available for parenteral use in anesthesia (Sublimaze), has now been marketed in a controlled-release transdermal formulation (Duragesic - Janssen) for use in patients with chronic pain severe enough to require opioid analgesia. It is not recommended for treatment of postoperative pain because of the drug's slow onset and prolonged duration of action.

Capsaicin, a vanillyl alkaloid found in hot peppers and related plants, is now available without a prescription as Zostrix-HP (GenDerm) for topical relief of pain due to diabetic neuropathy, herpes zoster, or arthritis. The new formulation contains 0.075% capsaicin; the drug was previously available in a 0.025% concentration as Zostrix.

Dezocine (Dalgan - Astra), a new synthetic opioid agonist/antagonist structurally related to pentazocine (Talwin), was recently approved for parenteral use as an analgesic by the US Food and Drug Administration.

Ketorolac (kee'; toe role ak) tromethamine (Toradol), manufactured by Syntex but also marketed by Roche, is the first parenteral nonsteroidal anti-inflammatory drug (NSAID) to become available for analgesic use in the USA. Parenteral indomethacin (Indocin I.V.) has been marketed here since 1985, but only for treatment of patent ductus arteriosus in newborn infants. Other parenteral NSAIDs are available in other parts of the world, but low potency, poor aqueous solubility, and substantial tissue irritation on injection have limited their usefulness. Ketorolac has been approved by the US Food and Drug Administration for intramuscular (IM) treatment of moderate to severe pain.

Since the implication of aspirin in Reye's syndrome, acetaminophen (Tylenol; and others) has become the standard drug for symptomatic treatment of fever and pain in children. Ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID) available for many years in tables (Mortin; Advil; and others), has now become available in a suspension. The suspension will be sold by presecription for treatment of fever or arthritis in children.

Automated intravenous delivery systems have recently become commercially available for intermittent self-administration of analgesics. Patient-controlled analgesia (PCA) has been used effectively to relieve after a wide variety of surgical procedures. It has also been effective for pain associated with labor, sickle cell crisis, and chronic pain caused by cancer.