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| Pronunciation | /θəˈlɪdəmaɪd/[1] |
| Trade names | Contergan, Thalomid, others |
| Other names | α-Phthalimidoglutarimide |
| AHFS/Drugs.com | Monograph |
| MedlinePlus | a699032 |
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| Routes of administration | By mouth |
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| Pharmacokinetic data | |
| Bioavailability | 90% |
| Protein binding | 55% and 66% for the (R)-(+)- and (S)-(−)-enantiomers, respectively[5] |
| Metabolism | Liver (minimally viaCYP2C19-mediated 5-hydroxylation; mostly via non-enzymatic hydrolysis at the four amide sites)[5] |
| Eliminationhalf-life | 5–7.5 hours (dose-dependent)[5] |
| Excretion | Urine, feces and semen[5] |
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| CompTox Dashboard(EPA) | |
| ECHA InfoCard | 100.000.029 |
| Chemical and physical data | |
| Formula | C13H10N2O4 |
| Molar mass | 258.233 g·mol−1 |
| 3D model (JSmol) | |
| Chirality | Racemic mixture |
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Thalidomide, sold under the brand namesContergan andThalomid among others, is anoral medication used to treat a number of cancers (e.g.,multiple myeloma),graft-versus-host disease, and manyskin disorders (e.g., complications ofleprosy such asskin lesions).[6][7] Thalidomide has been used to treat conditions associated withHIV:aphthous ulcers, HIV-associatedwasting syndrome, diarrhea, andKaposi's sarcoma, but increases in HIV viral load have been reported.[6]
Common side effects includesleepiness,rash, anddizziness.[6] Severe side effects includetumor lysis syndrome,blood clots, andperipheral neuropathy.[8] Thalidomide is a known humanteratogen and carries an extremely high risk of severe, life-threatening birth defects if administered or taken during pregnancy.[6] It causes skeletal deformities such asamelia (absence of legs and/or arms), absence of bones, andphocomelia (malformation of the limbs). A single dose of thalidomide, regardless of dosage, is enough to causeteratogenic effects.[6]
Thalidomide was first marketed in 1957 in West Germany, where it was availableover-the-counter.[9][10] When first released, thalidomide was promoted foranxiety,trouble sleeping, "tension", andmorning sickness.[10][11] While it was initially thought to be safe in pregnancy,concerns regarding birth defects arose, resulting in its removal from the market in Europe in 1961.[9][10] The total number of infants severely harmed by thalidomide use during pregnancy is estimated at over 10,000, possibly 20,000, of whom about 40% died around the time of birth.[6][10] Those who survived had limb, eye, urinary tract, and heart problems.[9] Its initial entry into the US market was prevented byFrances Kelsey, a reviewer at the FDA.[11] The birth defects caused by thalidomide led to the development of greaterdrug regulation and monitoring in many countries.[9][11]
It was approved in the United States in 1998 for use as a treatment for cancer.[6] It is on theWorld Health Organization's List of Essential Medicines.[12] It is available as ageneric medication.[8][13]
Thalidomide is used as a first-line treatment formultiple myeloma in combination withdexamethasone or withmelphalan andprednisone to treat acute episodes oferythema nodosum leprosum, as well as for maintenance therapy.[14][15]
The bacterium that causestuberculosis (TB) is related toleprosy. Thalidomide may be helpful in some cases wherestandard TB drugs andcorticosteroids are not sufficient to resolve severe inflammation in the brain.[16][17]
It is used as a second-line treatment to managegraft-versus-host disease andaphthous stomatitis in children and has been prescribed for other conditions in children, includingactinic prurigo andepidermolysis bullosa; the evidence for these uses is weak.[18] It is recommended only as a third line treatment in graft-versus-host-disease in adults because of lack of efficacy and side effects observed in clinical trials.[19][20]
Prescriptions of thalidomide are accompanied by strict measures to avoid any possibility of use during pregnancy, and thalidomide should be avoided in women wanting to conceive.[21] In the United States, the prescribing doctor is required to ensure thatcontraception is being used and that regular pregnancy tests are taken.[15][14]
Thalidomidecauses birth defects.[14][15][22][23] The U.S.Food and Drug Administration (FDA) and other regulatory agencies have approved marketing of the drug only with an auditablerisk evaluation and mitigation strategy that ensures that people using the drug are aware of the risks and avoid pregnancy; this applies to both men and women, as the drug can be transmitted insemen.[22][failed verification][21]
There is a high risk that thalidomide can cause excessiveblood clots. There is also a high risk that thalidomide can interfere with the production of several types of new blood cells, creating a risk of infection vianeutropenia,leukopenia, andlymphopenia, and risks that blood will not clot viathrombocytopenia. There is also a risk ofanemia via lack of red blood cells. The drug can also damage nerves, causing potentially irreversibleperipheral neuropathy.[14][15]
Thalidomide has several adverse cardiovascular effects, including risk ofheart attacks,pulmonary hypertension, and changes in heart rhythm, such assyncope,bradycardia, andatrioventricular block.[14][15]
Thalidomide can causeliver damage and severe skin reactions likeStevens–Johnson syndrome. It tends to make people sleepy, which creates risk when driving and operating other machinery. As it kills cancer cells, it can causetumor lysis syndrome. Thalidomide canprevent menstruation.[14][15]
In addition, very common (reported in more than 10% of people) adverse effects includetremor, dizziness, tingling, numbness, constipation, andperipheral edema.[14][15]
Common adverse effects (reported by 1–10% of people) include confusion, depressed mood, reduced coordination, heart failure, difficulty breathing, interstitial lung disease, lung inflammation, vomiting, dry mouth, rashes, dry skin, fever, weakness, and a sense of unwellness.[14][15]
There are no expectedpharmacokinetic interactions between thalidomide and other medicines due to its neutral effects onP-glycoprotein and thecytochrome P450 family. It may interact with sedatives due to its sedative action and bradycardic agents, like beta-blockers, due to its bradycardia-inducing effects. The risk ofperipheral neuropathy may be increased by concomitant treatment of thalidomide with other agents known to cause peripheral neuropathy.[24] The risk ofvenous thromboembolisms with thalidomide seems to be increased when patients are treated withoral contraceptives or other cytotoxic agents (includingdoxorubicin andmelphalan) concurrently. Thalidomide may interfere with various contraceptives, and hence it is advised that women of reproductive age use at least two different means of contraception to ensure that no child will be conceived while they are taking thalidomide.[14][15][24]
As of 2013, eighteen cases of overdoses had been reported with doses of up to 14.4 grams, none of them fatal.[24] No specific antidote for overdose exists and treatment is purelysupportive.[24]
The precise mechanism of action for thalidomide was not known until the twenty-first century,[25] although efforts to identify thalidomide'steratogenic action generated more than 2,000 research papers and the proposal of 15 or 16 plausible mechanisms by 2000.[26] The primary mechanism of action of thalidomide and its analogs in both their anti-cancer and teratogenic effects is now known to be ascereblonE3 ligase modulators.[25][27][28][29]
Thalidomide also binds to and acts as anantagonist of theandrogen receptor and hence is anonsteroidal antiandrogen of some capacity.[30] In accordance, it can producegynecomastia andsexual dysfunction as side effects in men.[31]
Thalidomide is provided as aracemic mixture of twoenantiomers; while there are reports that only one of the enantiomers may cause birth defects, the body converts each enantiomer into the other through mechanisms that are not well understood.[22] The (R)-enantiomer has the desired sedative effect while the (S)-enantiomer harbors embryo-toxic and teratogenic effects. Attempting to extract solelyR-thalidomide does not remove the risk of birth defects, as it was demonstrated that the "safe"R-thalidomide undergoes anin vivochiral inversion to the "teratogenic"S-thalidomide. Under biological conditions, the enantiomers interconvert (bidirectional chiral inversion – (R)- to (S)- and vice versa).[32][33]
Thalidomide isracemic; whileS-thalidomide is the bioactive form of the molecule, the individual enantiomers canracemize to each other due to the acidic hydrogen at thechiral centre, which is the carbon of theglutarimide ring bonded to thephthalimidesubstituent. The racemization process can occurin vivo.[5][34][35][36] The process of conversion of one enantiomer to its mirror-image version with no other change in the molecule is called chiral inversion.[37]
Celgene Corporation originally synthesized thalidomide using a three-step sequence starting withL-glutamic acid treatment, but this has since been reformed by the use ofL-glutamine.[38] As shown in the image below,N-carbethoxyphthalimide (1) can react withL-glutamine to yieldN-phthaloyl-L-glutamine (2). Cyclization ofN-phthaloyl-L-glutamine occurs usingcarbonyldiimidazole, which then yields thalidomide (3).[38] Celgene Corporation's original method resulted in a 31% yield ofS-thalidomide, whereas the two-step synthesis yields 85–93% product that is 99% pure.[citation needed]
In 2023, it is reported thatphthalic anhydride andL-glutamine under suitable conditions can react directly to form thalidomide. In the procedure, phthalic anhydride andL-glutamine are grounded and added intotoluene solvent. The solution, along withtriethylamine andacetic anhydride, is refluxed at ~110°C for 9 hours; after that the solution goes through a simplevacuum filtration procedure to obtain the product.[39]
In 1952, thalidomide was synthesised byChemical Industry Basel, but was found "to have no effect on animals" and was discarded on that basis.[40] In 1957, it was acquired byChemie Grünenthal in Germany.[40] The German company had been established as a soap maker after World War II ended, to address the urgent market need for antibiotics.[41]Heinrich Mückter[42] was appointed to head the discovery program based on his experience working with the German army's antiviral research. While preparingreagents for the work, Mueckter's assistant Wilhelm Kunz isolated a by-product that was recognized by pharmacologist Herbert Keller as an analog ofglutethimide, asedative. The medicinal chemistry work turned to improving the lead compound into a suitable drug: the result was thalidomide. The toxicity was examined in several animals, and the drug was introduced in 1956 as a sedative, but it was never tested on pregnant women.[43]
Researchers at Chemie Grünenthal found that thalidomide was a particularly effectiveantiemetic that had an inhibitory effect onmorning sickness.[44] On 1 October 1957, the company launched thalidomide and began marketing it under the trade name Contergan.[45][46] It was proclaimed a "wonder drug" forinsomnia, coughs, colds and headaches.[47]
During that period, the use of medications during pregnancy was not strictly controlled, and drugs were not thoroughly tested for potential harm to thefetus.[44] Thousands of pregnant women took the drug to relieve their symptoms. At the time of the drug's development, scientists did not believe any drug taken by a pregnant woman could pass across theplacental barrier and harm the developing fetus.[48] There soon appeared reports of abnormalities in children being born to mothers using thalidomide. In late 1959, it was noticed thatperipheral neuritis developed in patients who took the drug over a period of time, and it was only after this point that thalidomide ceased to be provided over the counter.[49]
While initially considered safe, the drug was responsible forteratogenic deformities in children born after their mothers used it during pregnancies, prior to the third trimester. In November 1961, thalidomide was taken off the market due to massive pressure from the press and public.[50] Experts estimate that thalidomide led to the death of approximately 2,000 children and serious birth defects in more than 10,000 children, with over half of them in West Germany.[51] The regulatory authorities inEast Germany never approved thalidomide.[52] One reason for the initially unobserved side effects of the drug and the subsequent approval in West Germany was that at that time drugs did not have to be tested for teratogenic effects. They were tested for toxicity on rodents only, as was usual at the time.[53]
In the UK, the British pharmaceutical companyThe Distillers Company (Biochemicals) Ltd, a subsidiary of Distillers Co. Ltd (now part ofDiageo plc), marketed thalidomide throughout the UK, Australia, and New Zealand, under the brand name Distaval, as a remedy formorning sickness. Their advertisement claimed that "Distaval can be given with complete safety to pregnant women and nursing mothers without adverse effect on mother or child ... Outstandingly safe Distaval has been prescribed for nearly three years in this country."[52] Globally, more pharmaceutical companies started to produce and market the drug under license from Chemie Grünenthal. Thalidomide was available in 46 countries under many different brand names.[54]
In the US, representatives from Chemie Grünenthal approachedSmith, Kline & French (SKF), nowGlaxoSmithKline, with a request to market and distribute the drug in North America. A memorandum, rediscovered in 2010 in the archives of the FDA, shows that in 1956–57, as part of its in-licensing approach, Smith, Kline and French conducted animal tests and ran a clinical trial of the drug in the US involving 875 people, including pregnant women.[55] In 1956, researchers involved in clinical trials at SKF noted that, even when used in very high doses, thalidomide could not induce sleep in mice.[56] When administered at doses 50 to 650 times larger than that claimed by Chemie Grünenthal to be "sleep-inducing", the researchers could still not achieve the hypnotic effect in animals that it had on humans.[citation needed] After completion of the trial, and based on reasons kept hidden for decades, SKF declined to commercialize the drug. In 1958, Chemie Grünenthal reached an agreement with the William S. Merrell Company in Cincinnati, Ohio (later Richardson-Merrell, now part ofSanofi), to market and distribute thalidomide throughout the US.[52]
The US FDA refused to approve thalidomide for marketing and distribution. However, the drug was distributed in large quantities for testing purposes, after the American distributor and manufacturerRichardson-Merrell had applied for its approval in September 1960.[57] The official in charge of the FDA review,Frances Oldham Kelsey, did not rely on information from the company, which did not include any test results. Richardson-Merrell was called on to perform tests and report the results. The company demanded approval six times and was refused each time. The distribution for "testing" resulted in 17 children born in the US with thalidomide-induced malformations. Oldham Kelsey was awarded thePresident's Award for Distinguished Federal Civilian Service by President Kennedy in 1962 for not allowing thalidomide to be approved for sale in the US. She was also inducted into theNational Women's Hall of Fame in 2000.[58]
Canada's Food and Drug Directorate approved the sale of thalidomide by prescription in November 1960.[59] There were many different forms sold: Kevadon, produced by the William S. Merrell Company seeking approval for its thalidomide product, was released on the market in April 1961, and the most common variant (Horner's Talimol) was put on the market on October 23 of the same year.[60] Two months after Talimol went on sale, pharmaceutical companies sent physicians letters warning about the risk of birth defects.[60] It was not until March 1962 that both drugs were banned from the Canadian market by the directorate, and soon afterward physicians were warned to destroy their supplies.[60]
In 1964, Israeli physicianJacob Sheskin administered thalidomide to a patient critically ill withleprosy. The patient exhibitederythema nodosum leprosum (ENL), a painful skin condition, one of the complications of leprosy. The treatment was attempted despite the ban on thalidomide's use, and the results were favourable: the patient slept for hours and was able to get out of bed without aid upon awakening. A clinical trial studying the use of thalidomide in leprosy soon followed.[61]
Thalidomide has been used by Brazilian physicians as the drug of choice for the treatment of severe ENL since 1965, and by 1996, at least 33 cases of thalidomide embryopathy were recorded in people born in Brazil after 1965.[62] Since 1994, the production, dispensing, and prescription of thalidomide have been strictly controlled, requiring women to use two forms of birth control and submit to regular pregnancy tests. Despite this, cases of thalidomide embryopathy continue,[63][64] with at least 100 cases identified in Brazil between 2005 and 2010.[65] Nearly 6 million thalidomide pills were distributed throughout Brazil in this time period, and these cases have occurred despite the controls.[66]
In 1998, the FDA approved the drug's use in the treatment of ENL.[67] Because of thalidomide's potential for causing birth defects, the drug may be distributed only under tightly controlled conditions. The FDA required thatCelgene Corporation, which planned to market thalidomide under the brand nameThalomid, establish a system for thalidomide education and prescribing safety (STEPS) oversight program. The conditions required under the program include limiting prescription and dispensing rights to authorized prescribers and pharmacies only, keeping a registry of all patients prescribed thalidomide, providing extensive patient education about the risks associated with the drug, and providing periodic pregnancy tests for women who take the drug.[67]
In 2010, theWorld Health Organization stated that it did not recommend thalidomide for leprosy due to the difficulty of adequately controlling its use, and due to the availability ofclofazimine.[68]
Shortly after the teratogenic properties of thalidomide were recognized in the mid-1960s, its anti-cancer potential was explored and two clinical trials were conducted in people with advanced cancer, including some people with multiple myeloma; the trials were inconclusive.[69]
Little further work was done with thalidomide in cancer until the 1990s.[69]
Judah Folkman pioneered studies into the role ofangiogenesis (the proliferation and growth of blood vessels) in the development of cancer, and in the early 1970s had shown thatsolid tumors could not expand without it.[70][71] In 1993 he surprised the scientific world by hypothesizing the same was true ofblood cancers,[72] and the next year he published work showing that abiomarker of angiogenesis was higher in all people with cancer, but especially high in people with blood cancers, and other evidence emerged as well.[73] Meanwhile, a member of his lab, Robert D'Amato, who was looking forangiogenesis inhibitors, discovered in 1994 that thalidomide inhibited angiogenesis[74] and was effective in suppressing tumor growth in rabbits.[75] Around that time, the wife of a man who was dying of multiple myeloma and whom standard treatments had failed, called Folkman asking him about his anti-angiogenesis ideas.[71] Folkman persuaded the patient's doctor to try thalidomide, and that doctor conducted a clinical trial of thalidomide for people with multiple myeloma in which about a third of the subjects responded to the treatment.[71] The results of that trial were published in the New England Journal of Medicine in 1999.[71][76]
After further work was done by Celgene and others, in 2006 the US Food and Drug Administration granted accelerated approval for thalidomide in combination with dexamethasone for the treatment of newly diagnosedmultiple myeloma patients.[71][77]
It was also evaluated whether thalidomide can be combined with melphalan and prednisone for patients with multiple myeloma. This combination of drugs probably increases the overall survival.[78]
In the late 1950s and early 1960s, more than 10,000 children in 46 countries were born with deformities, such asphocomelia, as a consequence of thalidomide use.[79] The severity and location of the deformities depended on how many days into the pregnancy the mother was before beginning treatment, with the time-sensitive window occurring approximately between day 20 and day 36 post-fertilisation.[51] Thalidomide taken on the 20th day of pregnancy caused central brain damage, day 22 the ears and face, day 24 the arms, and leg damage would occur if taken up to day 28.[80]
It is not known exactly how many worldwide victims of the drug there have been, although estimates range from 10,000 to 20,000.[81] Despite the side effects, thalidomide was sold in pharmacies in Canada until 1962.[60][82]
The disaster prompted many countries to introduce tougher rules for the testing and licensing of drugs, such as the 1962Kefauver Harris Amendment[91] (US), 1965Directive 65/65/EEC1 (EU),[92] and theMedicines Act 1968 (UK).[93][94] In the United States, the new regulations strengthened the FDA, among other ways, by requiring applicants to prove efficacy and to disclose all side effects encountered in testing.[79] The FDA subsequently initiated theDrug Efficacy Study Implementation to reclassify drugs already on the market.[95]
In 1977 the US Federal Drug Administration published a clinical trial guideline that excluded women of "childbearing potential" from the early phases of most clinical trials, which in practice led to their exclusion from later trial phases as well.[96] This 1977 FDA guideline was implemented in response to a protectionist climate caused by the thalidomide tragedy.[96] In the 1980s, a US task force on women's health concluded that a lack of women's health research (in part due to the FDA guideline) had compromised the amount and quality of information available about diseases and treatments affecting women.[96] This led to the National Institute of Health policy that women should, when beneficial, be included in clinical trials.[96]
In the 1960s, thalidomide was successfully marketed as a safer alternative tobarbiturates. Due to a successful marketing campaign, thalidomide was widely used by pregnant women during the first trimester of pregnancy. However, thalidomide is ateratogenic substance, and a proportion of children born during the 1960s had thalidomide embryopathy (TE).[97] Of these babies born with TE, "about 40% of them died before their first birthday".[98] The surviving individuals are now middle-aged and they report experiencing challenges (physical, psychological, and socioeconomic) related to TE.[99][100]
Individuals born with TE frequently experience a wide variety of health problems secondary to their TE. These health conditions include both physical and psychological conditions. When compared to individuals of similar demographic profiles, those born with TE report less satisfaction with their quality of life and their overall health.[97] Access to healthcare services can also be a challenge for these people, and women, in particular, have experienced difficulty in locating healthcare professionals who can understand and embrace their needs.[98]
Brand names include Contergan, Thalomid, Talidex, Talizer, Neurosedyn, Distaval, and many others.[7]
Research efforts have been focused on determining how thalidomide causes birth defects and its other activities in the human body, efforts to develop safer analogs, and efforts to find further uses for thalidomide.[101]
The exploration of theantiangiogenic and immunomodulatory activities of thalidomide has led to the study and creation of thalidomideanalogs.[102][103] Celgene has sponsored numerous clinical trials with analogues to thalidomide, such aslenalidomide, that are substantially more powerful and have fewer side effects — except for greatermyelosuppression.[104] In 2005, Celgene received FDA approval forlenalidomide (Revlimid) as the first commercially useful derivative. Revlimid is available only in a restricted distribution setting to avoid its use during pregnancy. Further studies are being conducted to find safer compounds with useful qualities. Another more potent analog,pomalidomide, is now FDA-approved.[105] Additionally,apremilast was approved by the FDA in March 2014. Thesethalidomide analogs can be used to treat different diseases, or used in a regimen to fight two conditions.[106]
Interest turned topomalidomide, aderivative of thalidomide marketed byCelgene. It is a very active anti-angiogenic agent[103] and also acts as animmunomodulator. Pomalidomide was approved in February 2013 by the FDA as a treatment for relapsed and refractorymultiple myeloma.[107] It received a similar approval from theEuropean Commission in August 2013, and is expected to be marketed in Europe under the brand nameImnovid.[108]
There is no conclusive evidence that thalidomide orlenalidomide is useful to bring about or maintain remission in Crohn's disease.[109][110]
Thalidomide was studied in a Phase II trial forKaposi's sarcoma, a rare soft-tissue cancer most commonly seen in the immunocompromised, that is caused by theKaposi's sarcoma-associated herpesvirus (KSHV).[111][44]
As they report in the current issue of Science, a protein known as cereblon latched on tightly to the thalidomide
