Source: Health Products and Food Branch (CA) Revision Year: 2022
3TC (lamivudine) in combination with other antiretroviral agents is indicated for the treatment of HIV infection.
Pediatrics (<18 years of age): 3TC is indicated in pediatric patients aged 3 months and older in combination with other antiretroviral agents.
Geriatrics (≥65 years of age): Clinical studies of 3TC did not include sufficient numbers of patients aged 65 and older to determine whether they respond differently from younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal or cardiac function and of concomitant disease or other drug therapy.
3TC therapy should be initiated by a physician experienced in the management of HIV infection.
3TC can be taken with or without food
The recommended oral dose of 3TC for adults and adolescents weighing at least 25 kg is 300 mg daily, administered as either 150 mg twice daily or 300 mg once daily (see 7 WARNINGS AND PRECAUTIONS, 10 CLINICAL PHARMACOLOGY and 14 CLINICAL TRIALS).
The recommended oral dose of 3TC Oral Solution for pediatric patients is 5 mg/kg (0.5 mL/kg) twice daily or 10 mg/kg (1 mL/kg) once daily (see 7.1.3 Pediatrics, Lower Virologic Suppression with Oral Solutions in Pediatrics).
3TC is also available as a scored tablet for HIV-1-infected pediatric patients weighing greater than or equal to 14 kg for whom a solid dosage form is appropriate. Before prescribing 3TC Tablets, children should be assessed for the ability to swallow tablets. If a child is unable to reliably swallow 3TC Tablets, the oral solution formulation should be prescribed. The recommended oral dosage of 3TC Tablets for HIV-1-infected pediatric patients is presented in Table 1. Patients changing between lamivudine oral solution and lamivudine tablets should follow the dosing recommendations that are specific for the formulation.
Table 1. Dosing Recommendations for 3TC Scored (150 mg) Tablets in Pediatric Patients:
| Weight (kg) | Once-Daily Dosing Regimen | Twice-Daily Dosing | Total Daily Dose | |
|---|---|---|---|---|
| AM Dose | PM Dose | |||
| 14 to <20 | 1 tablet (150 mg) | ½ tablet (75 mg) | ½ tablet (75 mg) | 150 mg |
| ≥20 to <25 | 1 ½ tablets (225 mg) | ½ tablet (75 mg) | 1 tablet (150 mg) | 225 mg |
| ≥25 | 2 tablets (300 mg) | 1 tablet (150 mg) | 1 tablet (150 mg) | 300 mg |
The limited data available are insufficient to propose specific dosage recommendations (see 10.3 Pharmacokinetics, Special Populations and Conditions, Pediatrics).
The safety and efficacy have not been established for pediatrics less than 3 month of age. Health Canada has not authorized an indication for pediatric patients less than 3 month of age.
No dose adjustment is necessary in patients with moderate or severe hepatic impairment unless accompanied by renal impairment.
Patients with impaired renal function have increases in Cmax and half-life of lamivudine with diminishing creatinine clearance. In addition, apparent total oral clearance of lamivudine decreases as creatinine clearance decreases. Doses of 3TC should be adjusted, as shown in Table 2 and Table 3 in accordance with creatinine clearance.
Table 2. Adjustment of Dosage of 3TC in Accordance With Creatinine Clearance in Adults, Adolescents and Children weighing ≥25 kg:
| Creatinine clearance (mL/min) | Recommended Dosage of 3TC |
|---|---|
| ≥50 | 150 mg twice daily or 300 mg once daily |
| 30-50 | 150 mg once daily |
| 15-29 | 150 mg first dose, then 100 mg once daily |
| 5-14 | 150 mg first dose, then 50 mg once daily |
| <5 | 50 mg first dose, then 25 mg once daily |
There are no data available on the use of lamivudine in children with renal impairment. A reduction in the dose and/or an increase in the dosing interval should be considered in children aged at least three months and weighing less than 25 kg with a creatinine clearance of less than 50 mL/min. The same percentage reduction in the adult dose is recommended for pediatric patients with renal impairment.
Table 3. Adjustment of Dosage of 3TC in Accordance with Creatinine Clearance in Children aged ≥3 months and weighing less than 25 kg:
| Creatinine clearance (mL/min) | Recommended Dosage of 3TC |
|---|---|
| 30-50 | 5 mg/kg once daily |
| 15-29 | 5 mg/kg first dose then 3.25mg/kg once daily |
| 5-14 | 5 mg/kg first dose then 1.63mg/kg once daily |
| <5 | 1.63mg/kg first dose then 0.88 mg/kg once daily |
If you forget to take your medicine, take it as soon as you remember. Then continue as before.
If overdosage occurs the patient should be monitored, and standard supportive treatment applied as required.
Administration of activated charcoal may be used to aid in the removal of unabsorbed active substance. General supportive measures are recommended.
Since lamivudine is dialyzable, continuous hemodialysis could be used in the treatment of overdose, although this has not been studied.
No specific signs or symptoms have been identified following acute overdose with lamivudine, apart from those listed as adverse reactions.
For management of a suspected drug overdose, contact your regional poison control centre.
3TC tablets should be stored between 2° and 30°C.
3TC oral solution should be stored between 2° and 25°C.
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