Main indications in lupus

Severe forms of lupus, especially with renal or central nervous system involvement

Dosage

Intravenous: 100 mg, 500 mg, 1000 mg:

0.5 to 0.7 mg/m2 of body surface every 2 to 4 weeks (<1200 mg/bolus)

Cyclophosphamide can be taken orally (1 to 2 mg/kg), but it is then more toxic because the total dose administered will be larger than intravenously.

Key Drug Interactions

- Acceleration of the destruction of cyclophosphamide (enzymatic induction): rifampicin, phenobarbital, phenytoin

- The association with drugs that have hepatic metabolism should be done with caution as this may change the effective rate of this drug

- Decrease in the destruction of cyclophosphamide (enzymatic inhibition): morphine, progesterone, quinine...

Main side effects

- Digestion: nausea, vomiting (especially in intravenous administration)

- Hair loss (alopecia): rare

- Absence of menstruation (amenorrhea) due to ovarian failure, particularly in the case of a cumulative dose above 10 g for subjects over 25 years of age

- Reduction in sperm quality (azoospermia): especially in case of cumulative dose higher than 10 g

- Infections

- Marrow toxicity (decrease in blood cells in the marrow)

- Bladder toxicity revealed by the presence of blood in the urine (haematuria) with a risk of cystitis,  predisposing to a bladder tumour

- Other cancers and lymphomas for high cumulative doses

Contraindications

- Pregnancy, lactation

- Bone marrow insufficiency

- Allergy

- Ongoing infection

- Haemorrhagic cystitis

- Severe hepatocellular insufficiency

Precautions for use

- Effective contraception up to 3 months after discontinuation of treatment due to the risk of malformation

- Resting of the ovaries to protect them by using contraception or hormone therapy to block ovulation

- Sperm storage for men treated with cyclophosphamide (in case of prolonged treatment)

- Dose reduction in case of renal or hepatic failure

- Prophylaxis of pneumocystosis: trimethoprime 800mg/sulfamethoxazole 160mg high dose 1 tablet every 2 days or pentamidine aerosols

- Intravenous hydration + uromitexanand and emptying the bladder before bedtime to reduce the risk of bladder toxicity

Monitoring

- Blood count: 2 / month (maximum drop in white blood cells on Day 10 after intravenous bolus)

- Dose reduction if neutropenia <1000/mm³ or lymphocytes <500/mm³

- Liver assessment, creatinine and ionogram: 1/month

- Urine strip with cystoscopy in case of persistent blood in the urine (haematuria)

- Clinical monitoring