Abacavir
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Drug reference
Leflunomide
Disease-modifying antirheumatic drug (DMARD) — pyrimidine synthesis inhibitor · Antirheumatic, Immunomodulator
Also known as Arava, Leflunomide Sodium
START
Baseline LFTs, CBC, BP, pregnancy test (women), TB screening. Verify contraception in women of childbearing potential. 100mg x 3 days loading OR start 20mg without loading (less GI toxicity).
TYPICAL MAX
20mg/day. Hepatotoxicity is the main safety concern—ALT must be monitored. If ALT >2x ULN: reduce to 10mg; if >3x ULN: discontinue and begin accelerated elimination.
STOP IF
ALT >3x ULN, severe rash (SJS/TEN), pancytopenia, interstitial pneumonitis, severe infection, pregnancy.
WATCH
LFTs monthly for first 6 months, then every 6-8 weeks. CBC periodically. BP (can cause hypertension). Weight loss. Hair loss (reversible). Drug elimination is very slow—cholestyramine 8g TID x 11 days is needed for rapid elimination if severe toxicity or pregnancy occurs.
CDSCO approvedSchedule HATC L04AA13
KDIGO 2024 + manufacturer label
- ONSET
- 1h · Onset ~1 hour
- PEAK
- 9h · Tmax parent 6-12h; metabolite 1-4 days
- t½
- 2.3w · t½ teriflunomide ~14-18 days
- DURATION
- 1d · 24 hours (QD); effects persist weeks
EXCRETION
Fecal as metabolites (~48%)
route + CYP
INTERACTIONS
12 major
SEVERE in our sources
PREGNANCY
CONTRAINDICATED in pregnancy—teratogenic. Women of childbearing potential must use reliable contraception during and until drug levels are undetectable (can take up to 2 years; accelerated elimination with cholestyramine 8g TID x 11 days reduces to <0.02 mg/L). Men should also use contraception during and until elimination confirmed.
FDA category + note
Top interactionssee all 12 →
- AbacavirSevereDatabaseDDInter
- AbemaciclibSevereDatabaseDDInter
- AbirateroneSevereDatabaseDDInter
- AcalabrutinibSevereDatabaseDDInter
Available in India
67 branded formulations. Look up specific brands in the Drugs workspace.
Mechanism
Inhibits dihydroorotate dehydrogenase (DHODH), the rate-limiting enzyme in de novo pyrimidine synthesis in rapidly dividing lymphocytes. Reduces T-cell proliferation and autoantibody production. Also inhibits tyrosine kinases and NF-κB activation.
Indications
Rheumatoid arthritis (moderate to severe)Psoriatic arthritisSystemic lupus erythematosus (off-label, refractory disease)
Dosing
- Adult
- RA loading: 100mg PO daily x 3 days, then 10-20mg PO daily. Maintenance: 10-20mg daily. Some start 20mg without loading. Arava also available in 10mg and 20mg tablets.
- Pediatric
- Not established in children for RA. Juvenile idiopathic arthritis: limited data.
- Renal adjustment
- No adjustment needed (hepatically metabolized).
- Hepatic adjustment
- Avoid in severe hepatic impairment; use caution in chronic liver disease.
- Geriatric
- No specific adjustment; monitor LFTs and BP closely.
- Max dose
- 20mg/day
Pharmacokinetics
Onset
Clinical improvement 4-8 weeks; maximal effect 3-6 months
Peak effect
Tmax leflunomide 6-12 hours; Tmax teriflunomide (active metabolite) 1-4 days; steady-state in ~2 months
Duration
24 hours (QD dosing); effects persist weeks after discontinuation due to long half-life
Half-life
~14-18 days (teriflunomide, active metabolite); very long elimination
Bioavailability
~80%
Protein binding
~99% (teriflunomide; albumin)
Metabolism
Rapidly converted in GI wall and plasma to teriflunomide (active metabolite) by first-pass metabolism; further hepatic metabolism; enterohepatic recirculation
Excretion
~48% fecal (mainly metabolites); ~28% renal (metabolites)
Contraindications
- Pregnancy or planning pregnancy (teratogenic)
- Severe hepatic impairment
- Severe immunodeficiency (e.g., AIDS)
- Bone marrow dysplasia
- Hypersensitivity to leflunomide or teriflunomide
- Concomitant live vaccines
Side effects
Common
DiarrheaElevated LFTsAlopecia (usually reversible)RashNauseaHypertensionHeadacheRespiratory infection
Serious
- Severe hepatotoxicity (can be fatal—requires monitoring)
- Severe myelosuppression (pancytopenia, agranulocytosis)
- Interstitial lung disease / pneumonitis
- Severe skin reactions (SJS/TEN, DRESS)
- Peripheral neuropathy
- Tuberculosis reactivation
- Malignancy (theoretical with immunosuppression)
Pregnancy & lactation
Pregnancy
CONTRAINDICATED in pregnancy—teratogenic. Women of childbearing potential must use reliable contraception during and until drug levels are undetectable (can take up to 2 years; accelerated elimination with cholestyramine 8g TID x 11 days reduces to <0.02 mg/L). Men should also use contraception during and until elimination confirmed.
Lactation
Contraindicated during breastfeeding—teriflunomide excreted in breast milk.
Drug interactions
Abemaciclib
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Abiraterone
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Acalabrutinib
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Acarbose
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Acitretin
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Adalimumab
Severe
Database
Drug interaction classified as: others.
Source: DDInter
Afatinib
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Aflibercept
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Aldesleukin
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Alectinib
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Alefacept
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Related guidelines
Ask House about Leflunomide
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, Katzung, BNF·Verified: 2026-05-19 · House clinical team·Cockpit curated: 2026-05-19