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Eflornithine

Eflornithine, sold under the brand name Vaniqa among others, is a medication used to treat African trypanosomiasis and excessive hair growth on the face in women.

It is used for the 2nd stage of sleeping sickness caused by T. b. gambiense and may be used with nifurtimox.

It is used intravenously or topically.

Pregnancy category C

Routes of administration

intravenous, topical

Bioavailability

100% (Intravenous)

Negligible (Dermal)

Not metabolised

Elimination half-life 8 hours

Excretion Kidneys

Common side effects when applied as a cream include rash, redness, and burning.

Side effects of the injectable form include bone marrow suppression, vomiting, and seizures.

Use  during pregnancy or breastfeeding is unknown.

It is recommended typically for children over the age of 12.

Sleeping sickness, or trypanosomiasis, is treated with pentamidine or suramin in the first phase of the disease, and with melarsoprol and eflornithine intravenous injection in the second phase of the disease. 

Efornithine is commonly given in combination with nifurtimox, which reduces the treatment time.

Eflornithine is also effective in combination with other drugs, such as melarsoprol and nifurtimox.

Nifurtimox-eflornithine combination treatment (NECT) is an effective regimen for the treatment of second stage gambiense African trypanosomiasis.

The topical cream is indicated for treatment of facial hirsutism in women, and is the only topical prescription treatment that slows the growth of facial hair.

81% percent of women showed clinical improvement after twelve months of treatment, with positive results were seen after eight weeks.

Discontinuation of the cream caused regrowth of hair back to baseline levels within 8 weeks.

Vaniqa reduces the psychological burden of facial hirsutism.

Ornithine decarboxylase (ODC) exhibits high activity in tumor cells, promoting cell growth and division, while absence of ODC activity leads to depletion of putrescine, causing impairment of RNA and DNA synthesis. 

By inhibiting ornithine decarboxylase, eflornithine inhibits cell growth and division of both cancerous and noncancerous cells.[

The  inhibition of ODC by eflornithine does not kill proliferating cells, making it ineffective as a chemotherapeutic agent. 

Eflornithine can aid in chemoprevention by lowering polyamine levels in colorectal mucosa, with additional strong preclinical evidence available for application of eflornithine in colorectal and skin carcinogenesis.

This has made eflornithine a supported chemopreventive therapy specifically for colon cancer in combination with other medications. 

Eflornithine in combination with other compounds decreases the carcinogen concentrations of ethylnitrosourea, dimethylhydrazine, azoxymethane, methylnitrosourea, and hydroxybutylnitrosamine in the brain, spinal cord, intestine, mammary gland, and urinary bladder.

Topical use is contraindicated in people hypersensitive to eflornithine .

There is no clinical evidence that treatment with Vaniqa adversely affects pregnant women or fetuses.

Eflornithine should only be used during pregnancy if the potential benefit outweighs the potential risk to the fetus.

In African trypanosomiasis has a high mortality rate if left untreated, treatment with eflornithine may justify any potential risk to the fetus.

Eflornithine is not genotoxic.

Np tumor-inducing effects have been observed in carcinogenicity studies.

No teratogenic effects have been detected.

The topical form of elflornithine is sold under the brand name Vaniqa,and its most frequently reported side effect is acne (7–14%). 

Other side effects commonly (> 1%) reported are skin problems, such as skin reactions from in-growing hair, hair loss, burning, stinging or tingling sensations, dry skin, itching, redness or rash.

The intravenous form of eflornithine is sold under the brand name Ornidyl. 

Most side effect are transient and reversible by discontinuing the drug or decreasing the dose. 

Hematologic abnormalities occur frequently, ranging from 10 to 55%,

are dose-related and are usually reversible. 

Thrombocytopenia is thought to be due to a production defect.

Seizures were seen in approximately 8% of patients, but may be related to the disease state rather than the drug. 

Reversible hearing loss has occurred in 30–70% of patients receiving long-term therapy.

High-frequency hearing is lost first, followed by middle- and low-frequency hearing loss.

Eflornithine irreversibly binding to ornithine decarboxylase (ODC) and preventing the natural substrate ornithine from accessing its active site of the enzyme.

Eflornithine is ineffective in treating malignancies.

It is highly effective in reducing hair growth,  as well as in the treatment of African trypanosomiasis.

Vaniqa is a cream, which is white to off-white in colour.

Ornidyl, intended for injection, was supplied in the strength of 200 mg eflornithine hydrochloride per ml.

Vaniqa, is currently the only topical prescription treatment that slows the growth of facial hair.

The FDA has approved eflornithine as a treatment to reduce the risk of relapse in adult and pediatric patients with high-risk neuroblastoma who have achieved at least a partial response to prior multi-agent, multimodality therapy including anti-GD2 immunotherapy.

Regarding safety, the most common adverse effects occurring in at least 5% of patients included otitis media, diarrhea, cough, sinusitis, pneumonia, upper respiratory tract infection, conjunctivitis, vomiting, pyrexia, allergic rhinitis, decreased neutrophils, increased alanine aminotransferase, increased aspartate transaminase, hearing loss, skin infection, and urinary tract infection.

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