Amifostine (ethiofos) is a cytoprotective adjuvant used in cancer

chemotherapy Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs (list of chemotherapeutic agents, chemotherapeutic agents or alkylating agents) in a standard chemotherapy re ...

and

radiotherapy Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle ...

involving

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

-binding chemotherapeutic agents. It is marketed by Clinigen Group under the trade name Ethyol.

Indications

Amifostine is used therapeutically to reduce the incidence of

neutropenia Neutropenia is an abnormally low concentration of neutrophils (a type of white blood cell) in the blood. Neutrophils make up the majority of circulating white blood cells and serve as the primary defense against infections by destroying bacteria ...

-related fever and infection induced by DNA-binding chemotherapeutic agents including

alkylating agent Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...

s (e.g.

cyclophosphamide Cyclophosphamide (CP), also known as cytophosphane among other names, is a medication used as chemotherapy and to suppress the immune system. As chemotherapy it is used to treat lymphoma, multiple myeloma, leukemia, ovarian cancer, breast cancer ...

) and platinum-containing agents (e.g.

cisplatin Cisplatin is a chemical compound with chemical formula, formula ''cis''-. It is a coordination complex of platinum that is used as a chemotherapy medication used to treat a number of cancers. These include testicular cancer, ovarian cancer, c ...

). It is also used to decrease the cumulative

nephrotoxicity Nephrotoxicity is toxicity in the kidneys. It is a poisonous effect of some substances, both toxic chemicals and medications, on kidney function. There are various forms, and some drugs may affect kidney function in more than one way. Nephrotoxin ...

associated with platinum-containing agents. Amifostine is also indicated to reduce the incidence of

xerostomia Xerostomia, also known as dry mouth, is a subjective complaint of dryness in the mouth, which may be associated with a change in the composition of saliva, reduced salivary flow, or have no identifiable cause. This symptom is very common and is o ...

in patients undergoing radiotherapy for head and neck cancer. Amifostine was originally indicated to reduce the cumulative renal toxicity from cisplatin in non-small cell

lung cancer Lung cancer, also known as lung carcinoma, is a malignant tumor that begins in the lung. Lung cancer is caused by genetic damage to the DNA of cells in the airways, often caused by cigarette smoking or inhaling damaging chemicals. Damaged ...

. However, while nephroprotection was observed, the probability that amifostine could protect tumors could not be excluded. Additional data have shown that amifostine-mediated tumor protection, in any clinical scenario, is unlikely.

Pharmacokinetics

Amifostine is an organic thiophosphate

prodrug A prodrug is a pharmacologically inactive medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be ...

which is hydrolysed ''

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, an ...

'' by

alkaline phosphatase The enzyme alkaline phosphatase (ALP, alkaline phenyl phosphatase, also abbreviated PhoA) is a phosphatase with the physiological role of dephosphorylating compounds. The enzyme is found across a multitude of organisms, prokaryotes and eukaryo ...

to the active cytoprotective

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl grou ...

metabolite, WR-1065. The selective protection of non-malignant tissues is believed to be due to higher alkaline phosphatase activity, higher pH, and vascular permeation of normal tissues. Amifostine can be administered intravenously or subcutaneously after reconstitution with

normal saline Saline (also known as saline solution) is a mixture of sodium chloride (salt) and water. It has a number of uses in medicine including cleaning wounds, removal and storage of contact lenses, and help with dry eyes. By intravenous therapy, inje ...

. Infusions lasting less than 15 minutes decrease the risk of adverse effects. The patient should be well-hydrated prior to administration.

Mechanism of action

Inside cells, amifostine detoxifies reactive metabolites of platinum and alkylating agents, as well as scavenges

free radicals In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired electron, unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemical reaction, chemi ...

. Other possible effects include accelerated

DNA repair DNA repair is a collection of processes by which a cell (biology), cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is cons ...

, induction of cellular hypoxia, inhibition of apoptosis, alteration of gene expression and modification of enzyme activity. Amifostine is believed to radioprotect normal tissue via

Warburg Warburg (; Westphalian: ''Warberich'' or ''Warborg'') is a town in eastern North Rhine-Westphalia, central Germany on the river Diemel near the three-state point shared by Hessen, Lower Saxony and North Rhine-Westphalia. It is in Höxter distr ...

-type effects.

Adverse effects

Common

side effect In medicine, a side effect is an effect of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects. A drug or procedure usually use ...

s of amifostine include

hypocalcemia Hypocalcemia is a medical condition characterized by low calcium levels in the blood serum. The normal range of blood calcium is typically between 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), while levels less than 2.1 ...

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

vomiting Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pre ...

, sneezing, somnolence, and

hiccups A hiccup (scientific name singultus, from Latin for "sob, hiccup"; also spelled hiccough) is an involuntary contraction ( myoclonic jerk) of the diaphragm that may repeat several times per minute. The hiccup is an involuntary action involvi ...

. Serious side effects include: hypotension (found in 62% of patients),

erythema multiforme Erythema multiforme (EM) is an immune-mediated inflammatory skin condition associated with several viral infections, that appears with red patches evolving into target lesions, typically on both hands. It is typically associated with infection ...

Stevens–Johnson syndrome Stevens–Johnson syndrome (SJS) is a type of severe skin reaction. Together with toxic epidermal necrolysis (TEN) and #Classification, Stevens–Johnson/toxic epidermal necrolysis (SJS/TEN) overlap, they are considered febrile mucocutaneous d ...

and

toxic epidermal necrolysis Toxic epidermal necrolysis (TEN), also known as Lyell's syndrome, is a type of severe skin reaction. Together with Stevens–Johnson syndrome (SJS) it forms a spectrum of disease, with TEN being more severe. Early symptoms include fever and f ...

, immune

hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) is an abnormal physiological condition in which there is an undesirable and adverse immune response to an antigen. It is an abnormality in the immune system that causes Imm ...

syndrome,

erythroderma Erythroderma is an inflammatory skin disease with erythema, redness and scaling that affects nearly the entire cutaneous surface.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. p. 436. . This te ...

anaphylaxis Anaphylaxis (Greek: 'up' + 'guarding') is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site. It typicall ...

, and loss of consciousness (rare).

Contraindications

Contraindications to receiving amifostine include

to amifostine and aminothiol compounds like WR-1065. Ethyol contains

mannitol Mannitol is a type of sugar alcohol used as a sweetener and medication. It is used as a low calorie sweetener as it is poorly absorbed by the intestines. As a medication, it is used to decrease pressure in the eyes, as in glaucoma, and to l ...

References

{{Detoxifying agents for antineoplastic treatment Chemotherapeutic adjuvants Prodrugs Amines