Terbinafine is a synthetic allylamine derivative with antifungal activity. Terbinafine exerts its effect through inhibition of squalene epoxidase, thereby blocking the biosynthesis of ergosterol, an important component of fungal cell membranes. As a result, this agent disrupts fungal cell membrane synthesis and inhibits fungal growth. Terbinafine is an Allylamine Antifungal. The chemical classification of terbinafine is Allylamine.
Terbinafine is an orally and topically active allylamine fungicidal agent which is used to treat superficial fungal infections of the skin and nails. Terbinafine has been clearly linked to rare instances of acute liver injury that can be severe and sometimes fatal.
Mechanism of Action of Terbinafine
Terbinafine is hypothesized to act by inhibiting squalene monooxygenase, thus blocking the biosynthesis of ergosterol, an essential component of fungal cell membranes. This inhibition also results in an accumulation of squalene, which is a substrate catalyzed to 2,3-oxy do squalene by squalene monooxygenase. The resultant high concentration of squalene and decreased amount of ergosterol are both thought to contribute to terbinafine’s antifungal activity.
Terbinafine hydrochloride (Lamisil) is a synthetic allylamine antifungal. It is highly lipophilic in nature and tends to accumulate in the skin, nails, and fatty tissues. Like other allylamines, terbinafine inhibits ergosterol synthesis by inhibiting the fungal squalene monooxygenase (squalene 2, 3-epoxidase), an enzyme that is part of the fungal cell wall synthesis pathway.
Indications of Terbinafine
- For the treatment of dermatophyte infections of the toenail or fingernail caused by susceptible fungi. Also for the treatment of tinea capitis (scalp ringworm) and tinea corporis (body ringworm) or tinea cruris (jock itch).
- Treatment of onychomycosis
- Terbinafine hydrochloride is indicated to treat fungal skin and nail infections caused by Trichophyton species, Microsporum canis, Epidermophyton floccosum,[rx] and Tinea species.[rx] Terbinafine hydrochloride also treats yeast infections of the skin caused by Candida species and Malassezia furfur.12
- Onychomycosis, Toenail
- Tinea Capitis
- Cutaneous Candidiasis
- Onychomycosis, Fingernail
- Tinea Corporis
- Tinea Cruris
- Tinea Pedis
Associated Conditions
- Candidiasis, Cutaneous
- Onychomycosis
- Pityriasis Versicolor
- Sporotrichosis
- Tinea Capitis
- Tinea Corporis
- Tinea Cruris
- Tinea Pedis
- Severe Tinea Corporis
- Severe Tinea Cruris
- Severe Tinea Pedis
Contraindication of Terbinafine
- Depression
- Liver problems
- Systemic lupus erythematosus
- An autoimmune disease
- Abnormal liver function tests
- A significant drop in a certain type of white blood cell called a neutrophil
- Allergies to Terbinafine Terbinafine/Butenafine
Dosage of Terbinafine
Strengths: 250 mg; 125 mg; 187.5 mg
Onychomycosis – Fingernail
- Tablets: 250 mg orally once a day
Duration of therapy
- Fingernail onychomycosis: 6 weeks
- Toenail onychomycosis: 12 weeks
Onychomycosis – Toenail
- Tablets: 250 mg orally once a day
Duration of therapy
- Fingernail onychomycosis: 6 weeks
- Toenail onychomycosis: 12 weeks
Tinea Capitis
- Oral granules: 250 mg orally once a day for 6 weeks
Tinea Corporis
- Tablets: 250 mg orally once a day for 2 to 4 weeks
Tinea Cruris
- Some experts recommend: Tablets: 250 mg orally once a day for 2 to 4 weeks
Tinea Pedis
- Some experts recommend: Tablets: 250 mg orally once a day for 2 to 6 weeks
Pediatric Dose for Tinea Capitis
4 years or older: Oral granules:
- Less than 25 kg: 125 mg orally once a day
- 25 to 35 kg: 187.5 mg orally once a day
- Greater than 35 kg: 250 mg orally once a day
- Duration of therapy: 6 weeks
For Children, Some Experts Recommend:
- Tablets: 5 mg/kg/day orally
Based on weight
- 10 to 20 kg: 62.5 mg orally once a day
- 21 to 40 kg: 125 mg orally once a day
- 41 kg or more: 250 mg orally once a day
Duration of therapy
- Trichophyton tonsurans infection: 2 to 4 weeks
- Microsporum canis infection: Longer duration needed.S
Side Effects of Terbinafine
The Most Common
- signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
- signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
- signs of muscle breakdown (e.g., discolored urine, unexpected muscle pain, aches)
- skin rash or itching
- symptoms of blood disorders (such as sore throat, fever, chills, mouth sores, or unusual bleeding or bruising)
- symptoms of liver problems (such as unusual fatigue, yellow eyes or skin, abdominal pain, dark urine, pale stools, itching, or loss of appetite)
- vision changes
- weight loss
- signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
- symptoms of a serious allergic reaction (such as hives, difficulty breathing, or swelling of the face or throat)
- symptoms of a serious skin rash (such as redness, blistering, peeling, or loosening of skin)
- bloating or feeling of fullness in the stomach
- diarrhea
- headache
- heartburn
- increased sensitivity to the sun
- loss of appetite
- nausea
- stomach pain (mild)
Common
- indigestion
- inflammation of the joints
- large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
- light-colored stools
- lower back or side pain
- muscle aches
- painful or difficult urination
- pains in the stomach, side, or abdomen, possibly radiating to the back
- persistent loss of appetite
- pinpoint red spots on the skin
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- red skin lesions, often with a purple center
- red, irritated eyes
- red, scaling, or crusted skin
- sores, ulcers, or white spots on the lips or in the mouth
- sores, welting, or blisters
- stomach pain, continuing
- swollen glands
- swollen lymph glands
- tightness in the chest
- troubled breathing with exertion
- ulcers, sores, or white spots in the mouth
- unexplained bleeding or bruising
Rare
- burning
- dryness
- flaking or peeling skin
- itching
- other signs of skin irritation not present before use of this medication
- peeling
- rash
- redness
- scabs
- skin discoloration
- skin lesions
- stinging
- tingling
- Body aches or pain
- diarrhea
- difficulty with breathing
- ear congestion
- a general feeling of discomfort or illness
- headache
- joint pain
- loss of appetite
- loss of voice
- nasal congestion
- nausea
- runny nose
- shivering
- skin rash or itching
- sneezing
- sore throat
- sweating
- trouble with sleeping
- Drug
Drug Interactions of Terbinafine
There may be an interaction between terbinafine and any of the following:
- amiodarone
- antipsychotic medications (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
- atomoxetine
- azole antifungals (e.g., fluconazole, itraconazole, ketoconazole)
- beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
- birth control pills
- caffeine and products that contain caffeine
- captopril
- carbamazepine
- carvedilol
- chloroquine
- chlorpheniramine
- cimetidine
- codeine
- cyclosporine
- dextromethorphan
- doxepin
- doxorubicin
- fesoterodine
- flecainide
- MAO inhibitors type B (e.g., maprotiline, selegiline)
- mercaptopurine
- methamphetamine
- mexiletine
- mirtazapine
- nefazodone
- oxycodone
- phenobarbital
- phenytoin
- pimozide
- primaquine
- primidone
- procainamide
- propafenone
- rifabutin
- rifampin
- Saccharomyces boulardii
- selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
- tamoxifen
- tamsulosin
- tetrabenazine
- theophylline
- tolbutamide
- tolterodine
- tramadol
- triazolam
- tricyclic antidepressants (e.g., amitriptyline, desipramine)
- venlafaxine
- warfarin
Pregnancy Category of Terbinafine
FDA Pregnancy Category B
Pregnancy
This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding
This medication passes into breast milk. If you are a breast-feeding mother and are taking terbinafine, it may affect your baby. Women taking terbinafine tablets should not breast-feed. If you are using the cream or spray, talk to your doctor about whether you should continue breast-feeding. The safety and effectiveness of using this medication have not been established for children.