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rent use of medications handled by or affecting the CYP3A4 enzyme system (may require serum level monitoring, dose or dosing interval alterations); OB, Lactation:
Safety not established; breast feeding not recommended in HIV-infected patients;
Pedi: Treatment-naı̈ve children ⬍4 wk and protease inhibitor experienced children
⬍6 mo (safety not established).
fosamprenavir (fos-am-pren-a-veer)
Lexiva, Telzir
Classification
Therapeutic: antiretrovirals
Pharmacologic: protease inhibitors
Pregnancy Category C
Adverse Reactions/Side Effects
Reflects use with other antiretrovirals CNS: headache, fatigue, mood disorders. CV:
MYOCARDIAL INFARCTION. GI: diarrhea, nausea, vomiting, abdominal pain,qliver enzymes. Derm: rash. Endo: glucose intolerance. GU: nephrolithiasis. Hemat:
neutropenia. Metab:qcholesterol, fat redistribution,qtriglycerides. Misc: aller-
Indications
gic reactions including STEVENS-JOHNSON SYNDROME, ANGIOEDEMA, immune reconstitution syndrome.
With other antiretrovirals in the management of HIV infection.
Action
Inhibits the action of HIV protease and prevents the cleavage of viral polyproteins.
Therapeutic Effects: Increased CD4 cell counts and decreased viral load with
subsequent slowed progression of HIV and its sequelae.
Pharmacokinetics
Absorption: Fosamprenavir is a prodrug. Following oral administration, it is rapidly converted to amprenavir by the gut lining during absorption.
Distribution: Penetration into RBCs is concentration dependent.
Metabolism and Excretion: Mostly metabolized the liver (CYP3A4 enzyme system). Minimal renal excretion.
Half-life: 7.7 hr.
TIME/ACTION PROFILE (blood levels)
ROUTE
ONSET
PEAK
DURATION
PO
rapid
1.5–4 hr
12–24 hr
Contraindications/Precautions
Contraindicated in: Hypersensitivity, sulfonamide/sulfa hypersensitivity; Severe
hepatic impairment; Concurrent use of flecainide, propafenone, rifampin, ergot derivatives, St. John’s wort, lovastatin, simvastatin, pimozide, delavirdine, sildenafil
(Revatio), alfuzosin, midazolam or triazolam.
Use Cautiously in: Geri: Consider age-relatedpin body mass, cardiac/hepatic/
renal impairment, concurrent illness and medications; Hepatic impairment; Concur⫽ Canadian drug name.
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⫽ Genetic Implication.
Interactions
Drug-Drug: Amprenavir, the active moiety of fosamprenavir is metabolized by
CYP3A4; it also inhibits and induces this enzyme system. The action of any other
medication that is also handled by or affects this system may be altered by concurrent
use.qblood levels and risk of toxicity from flecainide, propafenone, rifampin, ergot derivatives (dihydroergotamine, ergotamine, ergonovine, methylergonovine), lovastatin, simvastatin, pimozide, delavirdine, sildenafil
(Revatio), alfuzosin, midazolam, or triazolam; concurrent use contraindicated. Blood levels arepby efavirenz (additional ritonavir may be required when
used together), nevirapine, lopinavir/ritonavir, saquinavir, carbamazepine,
phenobarbital, phenytoin, dexamethasone, histamine H2-receptor antagonists, and proton-pump inhibitors; monitor forpantiretroviral activity. Concurrent use with raltegravir mayplevels of amprenavir and raltegravir. Levels areqby
indinavir and nelfinavir. Maypmethadone and paroxetine levels.qlevels and
risk of toxicity from amiodarone, lidocaine, quinidine (monitor blood levels),
ketoconazole, and itraconazole (dose of itraconazole or ketoconazole should
not exceed 200 mg/day when fosamprenavir is used with ritonavir or 400 mg/day
when used without), rifabutin (monitor for neutropenia,prifabutin dose by 50%
when used with fosamprenavir or by 75% when used with fosamprenavir with ritonavir), cyclosporine or tacrolimus (monitor blood levels of immunosuppressants),
calcium channel blockers (clinical monitoring recommended), some benzodiazepines (alprazolam, clorazepate, diazepam, flurazepam; dosepof benzodiazepine may be needed), sildenafil, tadalafil, vardenafil (use cautiously;pdose
of sildenafil to 25 mg every 48 hr, for tadalafil single dose should not exceed 10 mg in
CAPITALS indicate life-threatening, underlines indicate most frequent.
Strikethrough ⫽ Discontinued.
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any 72 hr period, dose of vardenafil should not exceed 2.5 mg every 24 hr if used
without ritonavir or 2.5 mg every 72 hr with ritonavir with monitoring for toxicity)
and tricyclic antidepressants (blood level monitoring recommended).qrisk of
myopathy with atorvastatin; do not exceed atorvastatin dose of 20 mg/day. May alter
the effects of warfarin (monitor INR) or hormonal contraceptives (use alternative method of contraception). Mayqfluticasone levels; concurrent use not recommended. Mayqrisk of adverse effects with salmeterol; concurrent use not recommended. Mayqbosentan levels; initiate bosentan at 62.5 mg once daily or every
other day; if patient already receiving bosentan, discontinue bosentan at least 36 hr
before initiation of fosamprenavir and then restart bosentan at least 10 days later at
62.5 mg once daily or every other day. Mayqtadalafil (Adcirca) levels; initiate tadalafil (Adcirca) at 20 mg once daily; if patient already receiving tadalfil (Adcirca),
discontinue tadalafil (Adcirca) at least 24 hr before initiation of fosamprenavir and
then restart tadalafil (Adcirca) at least 7 days later at 20 mg once daily. Mayqcolchicine levels;pdose of colchicine; do not administer colchicine if patients have renal
or hepatic impairment. Concurrent use with telaprevir mayplevels of fosamprenavir and telaprevir; avoid concurrent use. Concurrent use with boceprevir mayplevels of fosamprenavir and boceprevir; avoid concurrent use. Concurrent use with
maraviroc maypfosamprenavir levels andqmaraviroc levels; adjust maraviroc
dose to 150 mg twice daily.
Drug-Natural Products: Concurrent use of St. John’s wort is contraindicated;pblood levels and may lead topvirologic response.
Route/Dosage
PO (Adults): Treatment-naive patients without ritonavir— 1400 mg twice daily;
Treatment-naive patients with ritonavir— 1400 mg once daily with ritonavir 100
or 200 mg once daily, or 700 mg twice daily with ritonavir 100 mg twice daily. Protease inhibitor– experienced patients— 700 mg twice daily with ritonavir 100 mg
twice daily. If efavirenz is added to a once daily regimen using both fosamprenavir
and ritonavir, an additional 100 mg of ritonavir (total of 300 mg) should be given.
PO (Children ⱖ4 wk [Treatment-naı̈ve] or ⱖ6 mo [Protease inhibitor-experienced]): ⱖ20 kg— 18 mg/kg twice daily (not to exceed 700 mg twice daily)
with ritonavir 3 mg/kg twice daily (not to exceed 100 mg twice daily); 15– 19.9 kg—
23 mg/kg twice daily (not to exceed 700 mg twice daily) with ritonavir 3 mg/kg twice
daily (not to exceed 100 mg twice daily) 11– 14.9 kg— 30 mg/kg twice daily (not to
Plate # 0-Composite
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exceed 700 mg twice daily) with ritonavir 3 mg/kg twice daily (not to exceed 100 mg
twice daily); ⬍11 kg— 45 mg/kg twice daily (not to exceed 700 mg twice daily) with
ritonavir 7 mg/kg twice daily (not to exceed 100 mg twice daily).
Hepatic Impairment
PO (Adults): Mild hepatic impairment— 700 mg twice daily without ritonavir
(therapy-naive) or 700 mg twice daily with ritonavir 100 mg once daily (therapy-naive or protease inhibitor experienced); Moderate hepatic impairment— 700 mg
twice daily without ritonavir (therapy-naive) or 450 mg twice daily with ritonavir 100
mg once daily (therapy-naive or protease inhibitor experienced); Severe hepatic
impairment— 350 mg twice daily without ritonavir (therapy-naive) or 300 mg
twice daily with ritonavir 100 mg once daily (therapy-naive or protease inhibitor experienced).
NURSING IMPLICATIONS
Assessment
● Assess patient for change in severity of HIV symptoms and for symptoms of oppor-
tunistic infections throughout therapy.
● Assess patient for allergy to sulfonamides. May exhibit cross-sensitivity.
● Assess patient for skin reactions throughout therapy. Reactions may be
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severe and life threatening. Discontinue therapy if severe reactions or
moderate rashes with systemic symptoms occur.
Lab Test Considerations: Monitor viral load and CD4 cell count regularly during therapy.
May causeqserum glucose cholesterol, and triglyceride levels.
May causeqAST and ALT levels.
May cause neutropenia.
Potential Nursing Diagnoses
Risk for infection (Indications)
Noncompliance (Patient/Family Teaching)
Implementation
● Do not confuse Lexiva with Pexeva (paroxetine).
● PO: Tablets may be administered with or without food. Oral suspension should be
taken without food in adults and with food in children. Shake suspension vigorously before administering. Refrigeration of suspension may improve taste. If emesis occurs within 30 minutes after dosing, re-dose.
䉷 2015 F.A. Davis Company
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Evaluation/Desired Outcomes
CONTINUED
fosamprenavir
● Decrease in viral load and increase in CD4 cell counts.
● Delayed progression of AIDS and decreased opportunistic infections in patients
with HIV.
Why was this drug prescribed for your patient?
Patient/Family Teaching
● Emphasize the importance of taking fosamprenavir as directed. Advise patient to
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read the Patient Information that comes with the prescription prior to initiation
of therapy and with each prescription refill, in case of changes. Fosamprenavir
must always be used in combination with other antiretroviral drugs. Do not take
more than prescribed amount and do not stop taking without consulting health
care professional. Take missed doses as soon as remembered if within 4 hrs of
scheduled dose. If more than 4 hrs, skip dose, then return to regular schedule. If a
dose is skipped, do not double the next doses.
Instruct patient that fosamprenavir should not be shared with others.
Inform patient that fosamprenavir does not cure AIDS or prevent associated or opportunistic infections. Fosamprenavir does not reduce the risk of transmission of
HIV to others through sexual contact or blood contamination. Caution patient to
use a condom and to avoid sharing needles or donating blood to prevent spreading the AIDS virus to others. Advise patient that the long-term effects of fosamprenavir are unknown at this time.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional
before taking other medications because of potentially serious drug interactions.
Instruct patient to notify health care professional if nausea, vomiting, diarrhea, or
rash occurs.
Inform patient that redistribution and accumulation of body fat may occur, causing central obesity, dorsocervical fat enlargement (buffalo hump), peripheral
wasting, breast enlargement, and cushingoid appearance. The cause and longterm effects are not known.
May decrease effectiveness of hormonal contraceptives; advise patient to use a
nonhormonal form of contraception during therapy.
Emphasize the importance of regular follow-up exams and blood counts to determine progress and monitor for side effects.
⫽ Canadian drug name.
⫽ Genetic Implication.
CAPITALS indicate life-threatening, underlines indicate most frequent.
Strikethrough ⫽ Discontinued.
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