Thiocolchicoside (Muscoril, Myoril, Neoflax) is a

muscle relaxant A muscle relaxant is a drug that affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeu ...

with

anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as o ...

and

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

effects. How it works is unknown, but it is believed to be via antagonism of

nicotinic acetylcholine receptor Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral ne ...

s. However, it is also appears to be a

competitive Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

antagonist of GABA_A and

glycine receptors The glycine receptor (abbreviated as GlyR or GLR) is the receptor of the amino acid neurotransmitter glycine. GlyR is an ionotropic receptor that produces its effects through chloride current. It is one of the most widely distributed inhibitory ...

. As such, it has powerful

convulsant A convulsant is a drug which induces convulsions and/or epileptic seizures, the opposite of an anticonvulsant. These drugs generally act as stimulants at low doses, but are not used for this purpose due to the risk of convulsions and consequent exc ...

activity and should not be used in

seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with los ...

-prone individuals.

Side effects

Side effects of thiocolchicoside can include nausea, allergy and

vasovagal Reflex syncope is a brief loss of consciousness due to a neurologically induced drop in blood pressure and/or a decrease in heart rate. Before an affected person passes out, there may be sweating, a decreased ability to see, or ringing in ...

reactions. Liver injury,

pancreatitis Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types: acute pancreatitis, and chronic pancr ...

, seizures, blood cell disorders, severe cutaneous disorders,

rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of th ...

, and reproductive disorders have all been recorded in the French and European

pharmacovigilance Term Given By Tushar Sharma (UPES Batch 2025) Pharmacovigilance (PV, or PhV), also known as drug safety, is the pharmaceutical science relating to the "collection, detection, assessment, monitoring, and prevention" of adverse effects with pharma ...

databases and in the periodic updates that the companies concerned submit to regulatory agencies. These data do not specify the frequency of the disorders nor do they identify the most susceptible patient populations. Thiocolchicoside is

teratogenic Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology. The related t ...

in experimental animals and also damages chromosomes. Human data are limited to a follow-up of about 30 pregnant women (no major malformations) and reports of altered spermatogenesis, including cases of

azoospermia Azoospermia is the medical condition of a man whose semen contains no sperm. It is associated with male infertility, but many forms are amenable to medical treatment. In humans, azoospermia affects about 1% of the male population and may be seen ...

. In practice, there is no justification for exposing patients to the adverse effects of thiocolchicoside. It is better to use an effective, well-known analgesic for patients complaining of muscle pain, starting with

paracetamol Paracetamol, also known as acetaminophen, is a medication used to treat fever and mild to moderate pain. Common brand names include Tylenol and Panadol. At a standard dose, paracetamol only slightly decreases body temperature; it is inferior ...

. Although muscle relaxants may have the major side effect of sedation, thiocolchicoside is free from sedation effects, likely due to its lack of potentiation of GABA_A receptors.

Pharmacokinetics

Thiocolchicoside is broken down in the body to a

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

called 3-demethylthiocolchicine (also known as SL59.0955 or M2) that could damage dividing cells therefore inducing toxicity in the embryo, neoplastic changes and fertility reduction in males. Therefore, recommended oral dose should not exceed 7 days and intramuscular dose duration should not exceed 5 days.http://www.aifa.gov.it/en/content/thiocolchicoside-containing-products-systemic-use-important-information-regarding-indication Local skin preparations are less toxic.

References

{{Navboxes , title =

Pharmacodynamics Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms (fo ...

, list1 = {{Nicotinic acetylcholine receptor modulators Glucosides Phenol ethers Acetamides Tropones Heptalenes Thioethers Glycine receptor agonists GABAA receptor agonists Nicotinic antagonists Convulsants