The green, round pill stamped with the imprint “C 17” is a generic formulation of Teriflunomide (7 mg). Manufactured by companies such as Concord Biotech Limited, this prescription-only medication is an immunomodulatory agent primarily indicated for the treatment of relapsing forms of multiple sclerosis (MS).
Pill Identification
To accurately identify this specific medication and minimize the risk of dispensing or consumption errors, check the following physical descriptors:
- Imprint: Stamped with “C 17” on one side.
- Color: Light green to green.
- Shape: Round, biconvex (curved outward on both sides), and film-coated.
- Strength: Each tablet contains exactly 7 mg of Teriflunomide.
- Classification: It is a non-controlled, prescription-only selective immunosuppressant.
Mechanism of Action
Teriflunomide is a pyrimidine synthesis inhibitor that targets the underlying autoimmune response driving Multiple Sclerosis.
- Inhibition of DHODH: Teriflunomide works by selectively and reversibly inhibiting a mitochondrial enzyme called dihydroorotate dehydrogenase (DHODH).
- Halting Pyrimidine Synthesis: DHODH is required for de novo pyrimidine synthesis. Pyrimidines are essential building blocks that cells use to replicate DNA and RNA.
- Suppressing Overactive Immune Cells: While normal, resting body cells can recycle existing pyrimidines through a separate “salvage pathway,” rapidly dividing T and B lymphocytes (white blood cells) rely heavily on the de novo pathway to multiply. By blocking this pathway, Teriflunomide selectively halts the rapid proliferation of the overactive, auto-reactive lymphocytes responsible for attacking the myelin sheath around nerves in the central nervous system.
- The Result: It significantly decreases the frequency and severity of inflammatory relapses and slows the accumulation of physical disability in patients with MS without causing broad, total bone marrow suppression.
Indications and Dosage
The C 17 pill is indicated for the treatment of adults with relapsing forms of Multiple Sclerosis (MS), which includes clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease.
Standard Dosing Guidelines
- Typical Dose: Either 7 mg (one C 17 tablet) or 14 mg taken orally once daily.
- Administration: It can be taken at any time of day, with or without food.
- Routine Lab Tests: Before initiating a prescription, a physician must test the patient for latent tuberculosis (TB), evaluate a complete blood count (CBC), and record baseline blood pressure and liver function.
Side Effects
Because teriflunomide alters cell replication rates and is cleared heavily through the liver, patients should be actively monitored for side effects.
Common Side Effects
- Alopecia (Hair Thinning): Temporary hair loss or thinning is common during the first 6 months of treatment but usually resolves without stopping the medication.
- Diarrhea & Nausea
- Alanine Aminotransferase (ALT) Elevation: Asymptomatic rises in liver enzymes.
- Paresthesia: Tingling, burning, or “pins and needles” sensations in the hands or feet.
- Influenza or Upper Respiratory Tract Infections: Due to the drug’s mild immunomodulatory effect.
Serious Side Effects (Require Prompt Medical Evaluation)
- Severe Neutropenia/Lymphopenia: A dangerous drop in white blood cell counts, increasing the risk of life-threatening infections.
- Peripheral Neuropathy: Persistent numbness or progressive weakness in the extremities.
- Interstitial Lung Disease (ILD): New or worsening pulmonary symptoms, such as an unexplained dry cough and shortness of breath.
- Severe Skin Reactions: Rare instances of Stevens-Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN).
Warnings and Precautions
Teriflunomide carries major clinical warnings, including two severe box warnings regarding liver health and fetal development.
Boxed Warning: Severe Hepatotoxicity
- Liver Injury Risk: Teriflunomide can cause clinically significant, potentially fatal drug-induced liver injury.
- Monitoring: Serum transaminases (ALT and AST) must be checked at baseline and then monitored at least monthly for the first 6 months of treatment.
- Contraindication: It should never be started in patients with pre-existing, severe hepatic impairment.
Boxed Warning: Embryofetal Toxicity (Pregnancy Category X)
- Severe Risk to Fetuses: Teriflunomide causes severe birth defects and fetal death based on animal data. It is strictly contraindicated in pregnant individuals or those of childbearing potential who are not using reliable, highly effective contraception.
- The Male-Mediated Risk: Because the drug is present in human semen, male patients taking the C 17 pill who wish to father a child with a partner must also factor in this safety warning.
The Accelerated Elimination Procedure
Teriflunomide has an exceptionally long half-life, remaining in the body’s tissues for an average of 8 months to up to 2 years after taking the final pill. If a patient experiences severe toxicity or wishes to become pregnant, waiting for the drug to clear naturally is unsafe.
To bypass this, physicians use an accelerated elimination procedure. This involves administering either Cholestyramine (8 g every 8 hours) or Activated Charcoal Powder (50 g every 12 hours) for 11 consecutive days. This rapidly binds the drug in the digestive tract, clearing it from the bloodstream within weeks.
Critical Drug Interactions
- Live Vaccines: Patients must avoid receiving live attenuated vaccines (such as the MMR or shingles vaccine) during treatment and for at least 6 months post-discontinuation, as the drug’s immunosuppressive effect could allow the vaccine strain to cause active infection.
- CYP2C8 Substrates: Teriflunomide can increase systemic levels of drugs processed by the CYP2C8 pathway, such as Repaglinide (a diabetes medication).
- Warfarin: Teriflunomide can cause up to a 25% decrease in the international normalized ratio (INR), requiring highly frequent blood-clotting checks when co-administered with blood thinners.