WHAT IS THIS MEDICINE AND WHAT IS IT USED FOR?
Pirfenex contains pirfenidone, one of only two medicines approved to
treat idiopathic pulmonary fibrosis (IPF) — a serious, progressive lung
condition in which the lung tissue gradually becomes scarred and stiffened (a
process called fibrosis). 'Idiopathic' means the cause is unknown.
As the scarring worsens, the lungs become less and less able to transfer
oxygen into the blood, causing increasingly severe breathlessness and,
ultimately, respiratory failure.
Pirfenidone works by reducing the activity of multiple pathways that
drive the scarring process — including transforming growth factor-beta
(TGF-beta), a key driver of fibrosis. It does not reverse existing scarring,
but it significantly slows the rate at which new scarring develops — preserving
lung function for longer and improving survival. Pirfenex is used in adults
with mild to moderate IPF.
3. HOW TO TAKE THIS MEDICINE
Pirfenidone treatment is started gradually to allow the body to adjust
and minimise side effects: the dose is increased over the first 3 weeks. Week
1: one 200mg tablet three times daily (600mg/day). Week 2: two 200mg tablets
three times daily (1200mg/day). Week 3 onwards (maintenance): three 200mg
tablets three times daily (1800mg/day — the full target dose).
Each dose must be taken with food — at the time of a meal or snack. Take
three doses evenly spaced throughout the day — for example, with breakfast,
lunch, and dinner.
Taking pirfenidone with food is not a preference — it is essential. Food
significantly reduces the rate of absorption and substantially lowers the risk
of the most common side effects, particularly nausea and dizziness. Never take
pirfenidone on an empty stomach.
⚠ PATIENT TIP: Pirfenidone makes your skin much
more sensitive to sunlight (photosensitivity). Wear SPF 50+ sunscreen every day
— even on overcast or cloudy days — and cover up exposed skin when going
outdoors. Do not use sunbeds. This applies year-round, not just in summer.
4. POSSIBLE SIDE EFFECTS
|
How Common? |
Side Effects |
|
Very Common |
Nausea (most common —
usually manageable with food and dose titration), photosensitivity (sun
sensitivity — skin burns or rashes much more easily than usual), fatigue,
skin rash (particularly on sun-exposed areas), loss of appetite, diarrhoea,
indigestion |
|
Common |
Dizziness, headache,
weight loss, raised liver enzymes on blood tests, stomach pain, insomnia,
sinusitis |
|
Serious — Tell Your
Doctor |
Significant liver
toxicity (hepatotoxicity): jaundice (yellow skin or eyes), dark urine, severe
nausea, right upper tummy pain — pirfenidone requires regular liver function
monitoring. Severe skin reactions on sun-exposed areas (photosensitivity
reactions — from blistering to sunburn-like lesions). Severe nausea,
vomiting, or diarrhoea that prevents eating or requires hospitalisation. |
5. WHO SHOULD NOT TAKE THIS MEDICINE
Pirfenidone should not be taken alongside fluvoxamine (an antidepressant
and OCD medication) — this combination dramatically raises pirfenidone blood
levels. It must not be used in patients with severe liver disease (Child-Pugh
C) or end-stage kidney disease requiring dialysis.
Use with caution in mild to moderate hepatic impairment — liver function
monitoring is essential. Pirfenidone is not recommended during pregnancy.
⚠
PHOTOSENSITIVITY — YEAR-ROUND SUN PROTECTION: Almost all patients on
pirfenidone have increased sensitivity to sunlight. This is not limited to
summer or sunny days — UV exposure through cloud cover and glass can still
cause reactions. SPF 50+ sunscreen on all exposed skin, protective clothing,
and avoidance of direct sunlight during peak hours are essential throughout
treatment.
⚠
LIVER FUNCTION MONITORING: Liver function tests (ALT, AST) must be performed
before starting treatment, monthly for the first 6 months, and then every 3
months thereafter. If liver enzymes rise significantly, pirfenidone may need to
be paused or stopped.
⚠
DOSE TITRATION IS IMPORTANT: The gradual 3-week dose increase is designed to
reduce side effects. If you miss several days of doses or need to restart after
a break, the dose escalation should be repeated from the beginning. Never jump
straight to the full 1800mg/day dose without the titration period.
6. MEDICINES THAT INTERACT WITH THIS TREATMENT
Fluvoxamine (used for depression and OCD) is contraindicated alongside
pirfenidone — it significantly inhibits the enzyme CYP1A2 that metabolises
pirfenidone, causing dangerous drug build-up. Other CYP1A2 inhibitors
(ciprofloxacin and enoxacin antibiotics) also increase pirfenidone levels — use
with caution and consider dose reduction.
CYP1A2 inducers (tobacco smoking, omeprazole in some people) reduce
pirfenidone levels. Smoking significantly reduces pirfenidone effectiveness —
smoking cessation is strongly encouraged. Antacids (particularly those
containing aluminium/magnesium) do not significantly interact, but always
inform your respiratory specialist and pharmacist of all medicines.
7. HOW TO STORE THIS MEDICINE
Store below 30°C. Keep in original packaging away from moisture. Keep out
of reach of children.
8. PRESCRIPTION REQUIREMENT
|
Field |
Details |
|
Status |
Prescription Only
Medicine (POM) — Specialist (respiratory medicine) prescription required;
usually subject to funding/formulary approval criteria based on lung function
parameters (FVC) |
9. GUIDANCE FOR PATIENTS & CAREGIVERS
Take pirfenidone with food — with each of your three daily meals
(breakfast, lunch, and dinner) — every day. Never take it on an empty stomach.
Protect your skin from the sun every single day — use SPF 50+ sunscreen on all
exposed skin, wear long sleeves and a hat when outdoors, and avoid the midday
sun and sunbeds throughout your treatment. Attend all liver function blood test
appointments.
Start slowly with the dose titration as prescribed — do not skip ahead to
the full dose. If you smoke, stopping will make pirfenidone work better. If you
miss several doses or restart after a gap, go back to the starting dose and
re-titrate. Report severe nausea, yellow skin or eyes, or dark urine to your
respiratory specialist promptly.
10. PHARMACIST & PRESCRIBER NOTES
|
Field |
Details |
|
Clinical Dispensing
Notes |
Three-week dose
titration protocol mandatory: 200mg TDS week 1, 400mg TDS week 2, 600mg TDS
(full 1800mg/day) week 3 onward. Re-titration required after treatment
interruption of more than 14 consecutive days. With-food administration is
essential — not optional — reduces nausea and dizziness. LFT monitoring:
pre-treatment, monthly for first 6 months, then every 3 months — dose
modification or discontinuation for significant elevation. Photosensitivity
counselling: SPF50+, protective clothing, no sunbeds — year-round.
Fluvoxamine is absolutely contraindicated (CYP1A2 inhibitor).
Ciprofloxacin/enoxacin increase pirfenidone exposure — reduce pirfenidone
dose or use alternative antibiotic. Smoking significantly induces CYP1A2 —
smoking cessation is clinically important and should be reinforced at every
dispensing. Eligibility criteria: typically FVC >50% and ≤90% predicted —
confirm current lung function parameters before supplying. Generic Pirfenex
is equivalent to Esbriet — counsel on brand equivalence if switching. |
11. FREQUENTLY ASKED QUESTIONS
Q: Why does the dose start low and increase gradually?
Starting at a low dose and increasing over 3 weeks allows your body to
adjust to the medicine and significantly reduces side effects — particularly
nausea and dizziness. Starting at the full dose straight away would cause many
people to stop because of side effects. If you ever miss more than about 2
weeks of treatment and need to restart, you should begin the titration again
from scratch.
Q: Why is taking it with food so important?
Food slows the absorption of pirfenidone into the bloodstream, preventing
a large sudden spike in drug levels. This dramatically reduces the likelihood
of nausea and dizziness — the most common reasons people stop taking the
medicine. Consistent food intake with each dose is one of the most practical
things you can do to stay on treatment.
Q: How serious is the sun sensitivity?
Very — pirfenidone causes photosensitivity in most patients, which means
your skin is much more likely to burn or develop a rash in response to sunlight
or UV radiation. This applies even on cloudy days. Use SPF 50+ sunscreen every
day, wear long sleeves and a hat outdoors, avoid the midday sun, and never use
sunbeds. Sun-exposed skin reactions can range from mild redness to severe
blistering if precautions are not followed.
Q: Does smoking affect the medicine?
Yes — smoking activates an enzyme (CYP1A2) that breaks down pirfenidone
more quickly, reducing the amount in your bloodstream and making it less
effective. Stopping smoking is strongly recommended — it will improve how well
pirfenidone works, as well as being beneficial for your lung condition overall.