Nelfinavir dosage

Calcium supplements had no effect on plasma levels of nelfinavir or its M8 metabolite in 15 patients receiving nelfinavir 1.25 g twice daily as part of a HAART regimen. Calcium was given as calcium carbonate 1350 mg twice daily to 9 patients, and calcium gluconate/calcium carbonate 2950/300 mg twice daily to 6 patients, both for 14 days. Plasma levels of nelfinavir were measured before a dose and 3 hours after a dose. Similar results were reported in another study. No nelfinavir dosage adjustments appear necessary if calcium supplements are given. 

HIV infection in combination with other antiretrovirals PO (Fortovase) 1,200 mg 3 times a day or 1,000 mg twice a day in combination with ritonavir 100 mg twice a day. PO (Invirase) 1,000 mg (5X200 mg or 2X500 mg) twice a day in combination with ritonavir 100 mg twice a day. Dosage adjustments when given in combination therapy Delavirdine Fortovase 800 mg 3 times a day Lopinavir/ritonavir-. Fortovase 800 mg twice a day Nelfinavir. Fortovase 800 mg 3 times a day or 1,200 mg twice a day. Ritonavir. Fortovase or Invirase 1,000 mg twice a day... 

The most common adverse effects associated with nelfinavir are diarrhea and flatulence. Diarrhea often responds to antidiarrheal medications but can be dose-limiting. Nelfinavir is an inhibitor of the CYP3A system, and multiple drug interactions may occur (Tables 49-3 and 49-4). An increased dosage of nelfinavir is recommended when co-administered with rifabutin (with a decreased dose of rifabutin), whereas a decrease in saquinavir dose is suggested with concurrent nelfinavir. Co-administration with efavirenz should be avoided due to decreased indinavir levels. Nelfinavir has a favorable safety and pharmacokinetic profile for pregnant women compared with that of other Pis (Table 49-5) there is no evidence of human teratogenicity. 

Healthy volunteers were given protease inhibitors and statins, and the authors concluded that simvastatin should be avoided and that atorvastatin could be used with caution in people taking ritonavir and saquinavir (111). Dosage adjustment of pravastatin may be necessary with co-administration of ritonavir and saquinavir. Pravastatin does not alter the pharmacokinetics of nelfinavir, and thus appears to be safe for co-administration. 

Viracept (nelfinavir, AG-1343) of Agouron (La Jolla/CA, USA) in collaboration with Japan Tobacco (Tokyo, Japan) began only in July 1995 with phase II investigations. Dosages in phase II are set between 770 and 1030 mg daily. The viral count decreased between 15- and 75-fold in comparison with the base case. 

Withdrawal symptoms in a 40-year-old man maintained on methadone, necessitating an increase in dosage, were attributed to nelfinavir (14). 

The use of rifampicin with the protease inhibitors indinavir, nelfinavir, and amprenavir is contraindicated. However, these agents can be used with rifabutin after appropriate dosage reduction. Failure to reduce the dosage of rifabutin can result in toxic manifestations, such arthralgia and uveitis. 

It appears that nelfinavir does not have a clinically significant effect on the pharmacokinetics of caspofungin, and no dosage adjustment of caspofungin is required on combined use. 

Dosage decrease of nelfinavir to 1 g twice daily recommended. Avoid once daily regimens. A dose increase of lopinavir/ritonavir oral solution to 533/133 mg twice daily or lopinavir/ritonavir tablets to 600/150 mg twice daily may be needed. ... 

Rifabutin bioavailability is increased by amprenavir, atazanavir, fosamprenavir/ritonavir, indinavir, lopinavir/ritonavir, nelfinavir, tipranavir/ritonavir, and especially ritonavir, with an increased risk of toxicity. Rifabutin modestiy decreases the bioavailability of indinavir, neifinavir, and particuiarly saquinavir (with an increased risk of therapeutic faiiure), but has no effect on amprenavir, atazanavir, and ritonavir-boosted fosamprenavir. The combination of rifabutin with protease inhibitors may be used, but dosage adjustments of rifabutin or both drugs are often necessary. 

A man needed to have his levothyroxine dosage doubled when he took ritonavir/saquinavir, and another woman possibly had a similar reaction when given indinavir then nelfinavir. Conversely, another woman needed a markedly reduced dose of levothyroxine when given indinavir. 

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