2 DOSAGE AND ADMINISTRATION The 14-day lead-in period with immediate-release nevirapine tablets (200 mg once daily) must be strictly followed; it has been demonstrated to reduce the frequency of rash. ( 2.5 , 5.2 ) The nevirapine extended-release tablets must be swallowed whole and must not be chewed, crushed, or divided. ( 2.1 ) Adult patients must initiate therapy with one 200 mg tablet of immediate-release nevirapine once daily for the first 14 days, followed by one 400 mg tablet of nevirapine extended-release tablets once daily. ( 2.2 ) Adult patients already on a regimen of immediate-release nevirapine tablets twice daily can be switched to nevirapine extended-release tablets 400 mg once daily without the 14-day lead-in period of immediate-release nevirapine tablets. ( 2.2 ) Pediatric patients (ages 6 to less than 18 years with a BSA of 1.17 m 2 or greater) must initiate therapy with immediate-release nevirapine tablets (as 150 mg/m 2 of nevirapine oral suspension or as nevirapine tablet) at a dose not to exceed 200 mg per day administered once daily for the first 14 days, followed by nevirapine extended-release tablets 400 mg once daily. ( 2.3 ) Pediatric patients with a BSA of 1.17 m 2 or greater already on a regimen of twice daily nevirapine oral suspension or immediate-release nevirapine tablets can be switched to nevirapine extended-release tablets 400 mg once daily without the 14-day lead-in period of nevirapine oral suspension or immediate-release nevirapine tablets. ( 2.3 ) If any patient experiences rash during the 14-day lead-in period with immediate-release nevirapine tablets do not initiate nevirapine extended-release tablets until the rash has resolved. Do not continue the immediate-release nevirapine tablets lead-in dosing regimen beyond 28 days. ( 2.5 ) If dosing is interrupted for greater than 7 days, restart 14-day lead-in dosing. ( 2.5 ) 2.1 General Dosing Considerations Nevirapine extended-release tablets must be swallowed whole and must not be chewed, crushed, or divided. Children should be assessed for their ability to swallow tablets before prescribing nevirapine extended-release tablets. Nevirapine extended-release tablets can be taken with or without food. 2.2 Adult Patients Patients not currently taking immediate-release nevirapine tablets Patients must initiate therapy with one 200 mg tablet of immediate-release nevirapine daily for the first 14 days in combination with other antiretroviral agents. The 14-day lead-in period with nevirapine tablets 200 mg daily dosing must be strictly followed (the lead-in period has been observed to decrease the incidence of rash), followed by one 400 mg tablet of nevirapine extended-release once daily [see Dosage and Administration (2.5) and Warnings and Precautions (5.2) ] . If rash persists beyond the 14-day lead-in period with immediate-release nevirapine tablets, do not begin dosing with nevirapine extended-release tablets. The lead-in dosing with 200 mg once daily immediate-release nevirapine tablets should not be continued beyond 28 days, at which point an alternative regimen should be sought. Switching patients from immediate-release Nevirapine Tablets to Nevirapine Extended-Release Tablets Patients already on a regimen of immediate-release nevirapine tablets twice daily in combination with other antiretroviral agents can be switched to nevirapine extended-release tablets 400 mg once daily without the 14-day lead-in period. Patients already on a regimen of immediate-release nevirapine tablets twice daily who switch to nevirapine extended-release tablets therapy should continue with their ongoing clinical and laboratory monitoring. 2.3 Pediatric Patients Nevirapine extended-release tablets in pediatric patients is dosed based on body surface area (BSA) calculated using the Mosteller formula. All pediatric patients must initiate therapy with immediate-release nevirapine tablets (as 150 mg/m 2 of nevirapine oral suspension or as nevirapine tablets), at a dose not to exceed 200 mg per day, administered once daily for the first 14 days. This lead-in period should be used because it has been demonstrated to reduce the frequency of rash. This lead-in period is not required if the patient is already on a regimen of twice daily immediate-release formulation in combination with other antiretroviral agents. The recommended oral dose of nevirapine extended-release tablets for pediatric patients with a BSA of 1.17 m 2 or greater is 400 mg following the lead-in period with immediate-release nevirapine tablets. The total daily dose should not exceed 400 mg for any patient. fig1 2.4 Monitoring of Patients Intensive clinical and laboratory monitoring, including liver enzyme tests, is essential at baseline and during the first 18 weeks of treatment with nevirapine. The optimal frequency of monitoring during this period has not been established. Some experts recommend clinical and laboratory monitoring more often than once per month, and in particular, would include monitoring of liver enzyme tests prior to beginning the 14-day lead-in period with immediate-release nevirapine tablets, prior to initiation of nevirapine extended-release tablets, and at two weeks after initiation of nevirapine extended-release tablets therapy. After the initial 18-week period, frequent clinical and laboratory monitoring should continue throughout nevirapine extended-release tablets treatment [see Warnings and Precautions (5) ] . In some cases, hepatic injury has progressed despite discontinuation of treatment. Patients already on a regimen of immediate-release nevirapine tablets twice daily who switch to nevirapine extended-release tablets once daily should continue with their ongoing clinical and laboratory monitoring. 2.5 Dosage Adjustment Patients with Rash Discontinue nevirapine if a patient experiences severe rash or any rash accompanied by constitutional findings [see Warnings and Precautions (5.2) ] . Do not initiate therapy with nevirapine extended-release tablets if a patient experiences mild to moderate rash without constitutional symptoms during the 14-day lead-in period of immediate-release nevirapine tablets until the rash has resolved [see Warnings and Precautions (5.2) ] . The total duration of the once daily lead-in dosing period should not exceed 28 days at which point an alternative regimen should be sought. Patients with Hepatic Events If a clinical (symptomatic) hepatic event occurs, permanently discontinue nevirapine. Do not restart nevirapine after recovery [see Warnings and Precautions (5.1) ] . Patients with Dose Interruption For patients who interrupt nevirapine extended-release tablets dosing for more than 7 days, restart the recommended lead-in dosing with immediate-release nevirapine tablets, using one 200 mg tablet daily for the first 14 days. Patients with Renal Impairment Patients with CrCl greater than or equal to 20 mL per min and not requiring dialysis do not require an adjustment in dosing. The pharmacokinetics of nevirapine have not been evaluated in patients with CrCl less than 20 mL per min. An additional 200 mg dose of immediate-release nevirapine tablets following each dialysis treatment is indicated in patients requiring dialysis. Nevirapine metabolites may accumulate in patients receiving dialysis; however, the clinical significance of this accumulation is not known [see Clinical Pharmacology (12.3) ] . Nevirapine extended-release tablets have not been studied in patients with renal dysfunction.