Epclusa requires no dosage adjustment in most special populations, but some populations require careful evaluation. The following explains three situations separately.

I. Populations with Abnormal Liver or Kidney Function

1. Hepatic impairment

Patients with mild, moderate, or severe hepatic impairment (Child-Pugh A, B, or C) do not require dosage adjustment of Epclusa. Patients with decompensated cirrhosis receiving combination therapy with ribavirin require enhanced clinical and hepatic laboratory monitoring.

2. Mild to moderate renal impairment

Patients with mild or moderate renal impairment do not require dosage adjustment and can take it according to the conventional regimen.

3. Severe renal impairment and dialysis patients

For patients with severe renal impairment or end-stage renal disease requiring hemodialysis, no recommended dosage can be given. The main reason is that exposure to the predominant metabolite of sofosbuvir is significantly increased, and safety has not been established.

4. Precautions when combined with ribavirin

If the regimen contains ribavirin, patients with renal impairment should also refer to the ribavirin prescribing information and adjust its dosage if necessary.

II. Pregnant, Postpartum, and Breastfeeding Populations

1. Epclusa alone

Currently, there are insufficient human data to confirm the effect of Epclusa on pregnancy outcomes. Animal studies have not found evidence of adverse development, but the benefits and risks of medication during pregnancy still need to be weighed.

2. Combined with ribavirin

Epclusa combined with ribavirin is contraindicated in pregnant women and in men whose female partners are pregnant. Pregnancy should be avoided during treatment and for 6 months after stopping treatment; see the ribavirin prescribing information for details.

3. Breastfeeding

It is not known whether the components of Epclusa enter human breast milk. In animal studies, sofosbuvir metabolites and velpatasvir can enter breast milk, but no adverse effects on offspring were observed. During breastfeeding, the benefits to mother and infant and potential risks should be weighed.

4. Fertility

If combined with ribavirin, the information regarding pregnancy testing, contraception, and infertility also applies, and the ribavirin prescribing information should be consulted.

III. Pediatric and Elderly Populations

1. Pediatric patients

The safety and effectiveness of Epclusa in children under 18 years of age have not been established, and it is not recommended for pediatric patients for the time being.

2. Elderly patients

Clinical trials included a certain number of patients aged 65 and over, and no overall differences in safety or effectiveness were observed compared with younger patients. Dosage adjustment is not required solely because of age, but sensitivity in the elderly may be increased, and individualized observation is still needed.

3. Elderly patients taking multiple medications

Elderly patients often take multiple medications at the same time. Before medication, they should inform the doctor of all medications and avoid concomitant use with interacting drugs such as amiodarone, rifampin, and St. John's wort.