Derfin
Derfin Uses, Dosage, Side Effects, Food Interaction and all others data.
Derfin is an allylamine with a range of antifungal activity. It is fungicidal against dermatophytes, moulds and certain dimorphic fungi. Derfin is either fungicidal or fungistatic against yeasts, depending on the species. Derfin interferes with fungal ergosterol biosynthesis by inhibiting squalene epoxidase in the fungal cell membrane at an early stage. This leads to a deficiency in ergosterol and to intracellular accumulation of squalene, resulting in fungal cell death. Derfin is highly effective in fungal infections of the skin, hair and nails caused by Trichophyton spp., Microsporum spp. and Epidermophyton floccosum. It is also effective against yeast infections of the skin, principally those caused by the genus candida. Topical terbinafine appears to be effective in pityriasis versicolor due to Pityrosporum arbiculare.
Derfin is an allylamine antifungal that inhibits squalene epoxidase (also known as squalene monooxygenase) to prevent the formation of ergosterol and cause an accumulation of squalene, weakening the cell wall of fungal cells. Derfin distributes into tissues and has a long terminal elimination half life, so the duration of action is long. Overdose with terbinafine is rare, even above the therapeutic dose, so the therapeutic index is wide. Patients taking oral terbinafine should have liver function tests performed prior to treatment to reduce the risk of liver injury.
| Trade Name | Derfin |
| Availability | Prescription only |
| Generic | Terbinafine |
| Terbinafine Other Names | Terbinafina, Terbinafine, Terbinafinum |
| Related Drugs | nystatin topical, clotrimazole topical, ketoconazole topical, itraconazole, miconazole topical, Lamisil, Lotrisone, ciclopirox topical, griseofulvin, Jublia |
| Weight | 250mg, 1% |
| Type | Tablet, Cream |
| Formula | C21H25N |
| Weight | Average: 291.4299 Monoisotopic: 291.198699805 |
| Protein binding | Terbinafine is >99% bound to proteins in plasma, mostly to serum albumin, high and low density lipoproteins, and alpha-1-acid glycoprotein to a lesser extent. |
| Groups | Approved, Investigational, Vet approved |
| Therapeutic Class | Drugs for subcutaneous and systemic mycoses, Topical Antifungal preparations |
| Manufacturer | Alco Pharma Ltd |
| Available Country | Bangladesh |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
Derfin cream is used for the treatment of the following dermatological infections: interdigital tinea pedis (Athlete’s foot), tinea cruris (jock itch) or tinea corporis (ring worm) due to susceptible organisms and planter tinea pedis (mocasin type) due to Trichophyton spp.
Derfin tablet is used for the treatment of onychomycosis of the toe nail or finger nail due to dermatophytes and also by non-dermatophyte fungi.
Derfin is also used to associated treatment for these conditions: Onychomycosis, Pityriasis versicolor, Sporotrichosis, Tinea Capitis, Tinea Corporis, Tinea Cruris, Tinea Pedis, Cutaneous candidiasis, Severe Tinea Corporis, Severe Tinea Cruris, Severe Tinea Pedis
How Derfin works
Derfin inhibits the enzyme squalene monooxygenase (also called squalene epoxidase), preventing the conversion of squalene to 2,3-oxydosqualene, a step in the synthesis of ergosterol. This inhibition leads to decreased ergosterol, which would normally be incorporated into the cell wall, and accumulation of squalene.
Generation of a large number of squalene containing vesicles in the cytoplasm may leach other lipids away from, and further weaken, the cell wall.
Dosage
Derfin dosage
Topical application:
Derfin cream to affected areas once or twice daily for 1-2 weeks may be adequate for fungal infections of the skin but certain infections may require oral Derfin tablet therapy.Usual duration of treatment of Derfin cream:
- In Tinea corporis and Tinea cruris: 1-2 weeks.
- In Tinea pedis: 2-4 weeks (One week of treatment will normally suffice if the cream is applied twice daily.).
- In Cutaneous candidiasis: 1-2 weeks
- In Pityriasis (tinea) versicolor: 2 weeks.
To prevent relapses in fungal infection, treatment should be continued for a adequate length of time. To apply Derfin cream clean and dry the affected areas thoroughly and apply the cream once or twice a day to the affected skin and surrounding area in a thin layer and rub in lightly. In the case of intertriginous infections the application may be covered with a gauze strip, especially at night.
Oral administration:
Derfin tablet is essential for hair or nail infections:
- The usual oral dose: Derfin 250 mg daily for 2 to 12 weeks depending upon the infection.
- Finger nail onychomycosis: Derfin 250 mg once daily for 6 weeks.
- Toe nail onychomycosis: Derfin 250 mg once daily for 12 weeks.
Side Effects
Derfin Tablet: Abdominal discomfort, anorexia, nausea, diarrhoea, headache, rash and urticaria occasionally with arthralgia or myalgia. Less frequently taste disturbance. Rarely liver toxicity, photosensitivity, serious skin reactions etc.
Derfin Cream: Redness, itching, or stinging; rarely allergic reactions.
Toxicity
The subcutaneous LD50 in rats and mice is >2g/kg. The TDLO for women is 210mg/kg/6W.
Overdose data with terbinafine is rare, however symptoms are expected to be nausea, vomiting, abdominal pain, dizziness, rash, frequent urination, and headache. Treat overdose with activated charcoal as well as symptomatic and supportive therapy.
Precaution
Terbifine cream is for external use only. Contact with eyes should be avoided.Good general hygiene is necessary in conjunction with the use of Derfin in order to prevent reinfection (eg. from underwear, socks,shoes etc).
Derfin tablet is not recommended for patients with chronic or active liver disease. Before prescribing terbinafine, pre-existing liver disease should be assessed. Hepatotoxicity may occur in patients with and without pre-existing liver disease. Pretreatment serum transaminase (ALT and AST) tests are advised for all patients before taking terbinafine tablets.
Interaction
In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug classes: tricyclic antidepressants, selective serotonin reuptake inhibitors, beta-blockers, antiarrhythmics class 1C (e.g., flecainide and propafenone) and monoamine oxidase inhibitors Type B. Co-administration of terbinafine should be done with careful monitoring and may require a reduction in dose of the 2D6-metabolized drug.
Food Interaction
- Limit caffeine intake. Derfin may reduce the metabolism of caffeine by approximately 19%, monitor for increased effects of caffeine.
- Take with or without food.
Derfin Drug Interaction
Moderate: amphetamine / dextroamphetamine, duloxetine, metoprololUnknown: aspirin, diphenhydramine, ubiquinone, omega-3 polyunsaturated fatty acids, escitalopram, atorvastatin, pregabalin, esomeprazole, montelukast, levothyroxine, acetaminophen, cyanocobalamin, ascorbic acid, ergocalciferol, cholecalciferol, alprazolam, cetirizine
Derfin Disease Interaction
Major: liver disease, neutropeniaModerate: depression, immunosuppression, lupus, renal dysfunction
Volume of Distribution
A single 250mg oral dose of terbinafine has a volume of distribution at steady state of 947.5L or 16.6L/kg.
Elimination Route
Oral terbinafine is >70% absorbed but only 40% bioavailable after first pass metabolism, reaching a Cmax of 1µg/mL with a Tmax of 2 hours an an AUC of 4.56µg*h/mL. Over the course of a week, 1% topical terbinafine's Cmax increases from 949-1049ng/cm2
Half Life
Oral terbinafine has an effective half life of approximately 36 hours. However, the terminal half life ranges from 200-400 hours as it distributes into skin and adipose tissue. 1% topical terbinafine's half life increases over the first seven days from approximately 10-40 hours.
Clearance
A single 250mg oral dose of terbinafine has a clearance of 76L/h or 1.11L/h/kg.
Elimination Route
Derfin is approximately 80% eliminated in urine, while the remainder is eliminated in feces. The unmetabolized parent drug is not present in urine.
Pregnancy & Breastfeeding use
Derfin tablet: There are no adequate and well controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, and because treatment of onychomycosis can be postponed until after pregnancy is completed, it is recommended that terbinafine not be initiated during pregnancy. After oral administration, terbinafine is present in breast milk of nursing mothers. Treatment with terbinafine in not recommended in nursing mothers.
Derfin cream: Foetal toxicity and fertility studies in animals suggest no adverse effects. There is no clinical experience with terbinafine in pregnant women; therefore, unless the potential benefits outweigh any potential risk, terbinafine should not be administered. Derfin is excreted in breast milk and therefore mothers should not receive terbinafine treatment whilst breast-feeding.
Contraindication
Hypersensitivity to Derfin or any of the excipients in thepreparation
Special Warning
Use in Children: Derfin cream appears to be an effective and well-tolerated treatmenr of tinea corposis and tinea cruris in children.
Use in Elderly: Derfin appears to be safe in the elderly. The dose should be reduced by half if significant hepatic or renal impairment is present.
Acute Overdose
Clinical experience regarding overdose with terbinafine tablets is limited. Doses up to 5 grams (20 times the therapeutic daily dose) have been taken without inducing serious adverse reactions. The symptoms of overdose included nausea, vomiting, abdominal pain, dizziness, rash, frequent urination, and headache.
Storage Condition
Store in a cool and dry place, protected from light.
Innovators Monograph
You find simplified version here Derfin
Derfin contains Terbinafine see full prescribing information from innovator Derfin Monograph, Derfin MSDS, Derfin FDA label
FAQ
What is Derfin prescribed for?
Derfin are used to treat fungal infections of the toenails and fingernails. Derfin is in a class of medications called antifungals.
How safe is Derfin?
As with most classes of drugs, Derfin can potentially lead to liver problems.however Derfin is safer than perhaps it is perceived, and minor side effects are far more likely for most patients than serious liver damage.
What are the side effects of Derfin?
Common side effects are include:
- rash.
- headache.
- diarrhoea.
- feeling or being sick (nausea or vomiting)
- a smaller appetite than usual.
- stomach ache.
- indigestion.
- muscle or joint pain
How fast does Derfin work?
Derfin work within 1 week after starting therapy and persist for at least 30 weeks after the completion of treatment.
Is Derfin safe during pregnancy?
Derfin can be used relatively safely in both oral and topical formulations during pregnancy.
Can I take Derfin during breastfeeding?
Derfin tablets are generally not recommended if you're breastfeeding. There are other antifungal medicines that are safer. Your doctor will recommend the best medicine for you.
Can I drink alcohol with Derfin?
Yes, you can drink alcohol while using or taking Derfin.
Can I drive after taking Derfin?
Some people have reported feeling dizzy or giddy while they are taking Derfin. If you feel like this, you should not drive or operate machinery.
What is the best time of day to take Derfin?
Take Derfin tablets at the same time each day, either in the morning OR in the evening.
What is the best time of day to take Derfin?
Take Derfin tablets at the same time each day, either in the morning or in the evening.You can take Derfin with or without food.
Does Derfin affect the heart?
Derfin can affect your blood cells and your liver. You may need blood tests before you start and while you are taking Derfin to check your blood cells and see how well your liver is working.
What happen If I missed Derfin?
If you forget to take your dose, take it as soon as you remember that day. If it's nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Do not take 2 doses at the same time.
Will Derfin affect my fertility?
No effect of Derfin on fertility has been seen in animal studies and there are no data to suggest an effect on fertility in humans.
How long does Derfin stay in my system after stop taking Derfin ?
A terminal half-life of 200-400 hours may represent the slow elimination of Derfin from tissues such as skin and adipose.
What should I avoid while taking Derfin?
Avoid coffee, tea, cola, energy drinks or other sources of caffeine while taking Derfin.
What happens when I stop taking Derfin?
If you stop taking Derfin too soon, your symptoms may return. Derfin works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses.
Does hair grow back after Derfin?
Hair will grow back by itself once a person stops taking Derfin.
Is Derfin bad for my liver?
Some people taking Derfin have developed severe liver damage leading to liver transplant or death.
How fast does Derfin work?
Derfin is rapidly absorbed and widely distributed to body tissues including the poorly perfused nail matrix.
How long do side effects from Derfin last?
Derfin may resolve within several weeks after discontinuation of treatment, but may be prolonged,or may be permanent.
Does Derfin affect periods?
You may have problems, such as bleeding between periods, while you are taking Derfin . You may need to take different amounts of your medicines or you may need to take different medicines.
