Radiotherapy
Contraindicated
Textbook
Significant potentiation of radiotherapy effects, leading to severe toxicity.
Should not be used with radiotherapy.
Source: G&G 14e · p1360
Drug reference
Gemcitabine
Pyrimidine nucleoside analog antimetabolite · Antineoplastic
START
Confirm ANC ≥1500, platelets ≥100,000. Baseline CBC, LFTs, creatinine. Verify adequate hydration. Assess performance status.
TYPICAL MAX
1250mg/m² per dose. Dose-limiting toxicity is myelosuppression (especially thrombocytopenia).
STOP IF
ANC <500, platelets <25,000, grade ≥3 non-hematologic toxicity, HUS/TTP signs (anemia, thrombocytopenia, renal dysfunction, schistocytes).
WATCH
CBC before each dose (days 1 and 8 of each cycle). Renal function (HUS risk—rare but life-threatening). Pulmonary symptoms (interstitial pneumonitis). Infusion must be over 30 minutes (longer infusions increase toxicity without improving efficacy).
CDSCO approvedSchedule HATC L01BC05
KDIGO 2024 + manufacturer label
- ONSET
- 18min · Onset ~18 min
- PEAK
- 30min · Cmax at end of infusion
- t½
- 30min · Plasma t½ 8-17 min
- DURATION
- 1d · Intracellular effect 12-24h
EXCRETION
Renal as metabolite dFdU (~95%)
route + CYP
INTERACTIONS
12 major
incl. contraindicated
PREGNANCY
Contraindicated in pregnancy—embryotoxic and fetotoxic. Effective contraception required during and for 6 months after treatment (both sexes).
FDA category + note
Top interactionssee all 12 →
- RadiotherapyContraindicatedTextbookG&G 14e · p1360
- AdalimumabSevereDatabaseDDInter
- BaricitinibSevereDatabaseDDInter
- CertolizumabSevereDatabaseDDInter
Available in India
100 branded formulations. Look up specific brands in the Drugs workspace.
Mechanism
Deoxycytidine analog that is phosphorylated intracellularly to gemcitabine diphosphate (inhibits ribonucleotide reductase) and gemcitabine triphosphate (competes with dCTP for incorporation into DNA, causing chain termination and masked chain termination). Self-potentiating mechanism of action.
Indications
Non-small cell lung cancer (NSCLC)Pancreatic cancer (first-line, with nab-paclitaxel or as monotherapy)Breast cancer (with paclitaxel)Ovarian cancer (with carboplatin)Bladder cancer (with cisplatin)Biliary tract cancer (with cisplatin)Soft tissue sarcoma (off-label)
Dosing
- Adult
- Pancreatic: 1000mg/m² IV weekly x 7 weeks, then 1 week rest, then weekly x 3 of 4 weeks; OR 1250mg/m² days 1,8 q21 days with nab-paclitaxel. NSCLC: 1000-1250mg/m² days 1,8 q21 days (with cisplatin). Breast: 1250mg/m² days 1,8 q21 days (with paclitaxel). Ovarian: 1000mg/m² days 1,8 q21 days (with carboplatin).
- Pediatric
- Not routinely used in children.
- Renal adjustment
- CrCl ≥30: no adjustment. CrCl <30: limited data—use caution and reduce dose.
- Hepatic adjustment
- Bilirubin >1.6x ULN: limited data; use caution.
- Geriatric
- No specific adjustment; monitor closely for myelosuppression and renal toxicity.
- Max dose
- 1250mg/m² per dose (most indications); 2200mg/m² weekly (investigational)
Pharmacokinetics
Onset
Cell-cycle specific (S-phase); cytotoxic effect requires DNA synthesis
Peak effect
Cmax at end of 30-minute infusion; intracellular triphosphate peaks at ~1 hour post-infusion
Duration
Short plasma half-life; intracellular triphosphate persists 12-24 hours
Half-life
~8-17 minutes (plasma α-phase); ~30-90 minutes (β-phase); intracellular triphosphate t½ ~12-24h
Bioavailability
N/A (IV only)
Protein binding
<10%
Metabolism
Extensive intracellular phosphorylation; deamination by cytidine deaminase to inactive metabolite dFdU
Excretion
~92-98% renal (primarily as dFdU); <10% unchanged in urine
Contraindications
- Hypersensitivity to gemcitabine
- Severe myelosuppression
- Pregnancy
- Breastfeeding
Side effects
Common
Myelosuppression (neutropenia—dose-limiting, thrombocytopenia, anemia)Nausea and vomiting (mild-moderate)Fatigue / astheniaAlopeciaFeverRashElevated transaminases
Serious
- Febrile neutropenia
- Hemolytic uremic syndrome (HUS—rare but serious)
- Thrombotic microangiopathy / TTP-like syndrome
- Severe hepatotoxicity
- Pulmonary toxicity (interstitial pneumonitis)
- Capillary leak syndrome
- Posterior reversible encephalopathy syndrome (PRES—rare)
Pregnancy & lactation
Pregnancy
Contraindicated in pregnancy—embryotoxic and fetotoxic. Effective contraception required during and for 6 months after treatment (both sexes).
Lactation
Excretion in breast milk unknown; discontinue breastfeeding during treatment.
Drug interactions
Adalimumab
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Baricitinib
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Certolizumab
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Cladribine
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Clozapine
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Deferiprone
Severe
Database
Clinical effect not specified
Source: DDInter
Etanercept
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Fingolimod
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Golimumab
Severe
Database
Clinical effect not specified
Source: DDInter
Infliximab
Severe
Database
Clinical effect not specified
Source: DDInter
Leflunomide
Severe
Database
Clinical effect not specified
Source: DDInter
Related guidelines
Ask House about Gemcitabine
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Sources: Goodman & Gilman 14e, BNF·Verified: 2026-05-19 · House clinical team·Cockpit curated: 2026-05-19