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Drugs Jun 1998Amprenavir is a viral protease inhibitor with specificity for the HIV protease enzyme. The resistance profile of amprenavir appears to differ from that of other protease... (Comparative Study)
Comparative Study Review
Amprenavir is a viral protease inhibitor with specificity for the HIV protease enzyme. The resistance profile of amprenavir appears to differ from that of other protease inhibitors such as saquinavir and indinavir. Twelve hours after single-dose administration of amprenavir 1200mg to HIV-infected individuals, the mean plasma concentration of the drug was more than 10-fold greater than the 50% inhibitory concentration for HIV-1IIIB in peripheral blood lymphocytes. In a small nonblind study, amprenavir monotherapy increased CD4+ cell count and decreased viral load in 37 patients with HIV infection and no previous exposure to protease inhibitor therapy. Combination therapy comprising amprenavir and other antiretroviral agents (abacavir, zidovudine, lamivudine, indinavir, saquinavir or nelfinavir) decreased viral load and increased CD4+ cell counts in patients with HIV infection. Antiviral efficacy was maintained during up to 24 weeks' follow-up. Available data suggest that rash, headache and diarrhoea or loose stools are the most frequent adverse events associated with amprenavir therapy.
Topics: Animals; Anti-HIV Agents; CD4 Lymphocyte Count; Carbamates; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; In Vitro Techniques; RNA, Viral; Rats; Sulfonamides
PubMed: 9617598
DOI: 10.2165/00003495-199855060-00015 -
Drugs Dec 2000The virological/immunological efficacy of amprenavir-containing combination regimens has been evaluated in a small number of clinical trials in patients with HIV... (Review)
Review
UNLABELLED
The virological/immunological efficacy of amprenavir-containing combination regimens has been evaluated in a small number of clinical trials in patients with HIV infection. Amprenavir plus 2 nucleoside reverse transcriptase inhibitors (NRTIs) was more effective than 2 NRTIs (in treatment-naive patients) or amprenavir monotherapy (in treatment-naive or -experienced patients) in double-blind trials. In the only direct comparison with another protease inhibitor as part of triple therapy, amprenavir was less effective than indinavir in treatment-experienced (protease inhibitor-naive) patients. Amprenavir was as effective as other protease inhibitors when given with abacavir in a small nonblind trial. Amprenavir is generally well tolerated (most events are mild or moderate). GI disturbance and rash are the principal treatment-limiting effects. Preclinical data suggest that amprenavir may have a low potential for metabolic disturbances (e.g. lipodystrophy, fat redistribution); such effects have been infrequent in patients treated to date, but longer term experience is needed. 150V is the major HIV protease substitution associated with amprenavir resistance; this mutation is not seen in isolates from patients receiving other available protease inhibitors. Amprenavir-resistant isolates evaluated to date showed no significant cross-resistance to most other protease inhibitors, although some cross-resistance to ritonavir was noted. Many isolates from patients previously treated with other protease inhibitors are susceptible to amprenavir. Amprenavir offers the convenience of twice-daily administration with no food-timing or fluid restrictions, but this may be offset by the large number and size of the capsules. However, pharmacokinetic data support the use of co-administration of amprenavir and ritonavir at reduced dosages, thereby allowing a reduction in the number of amprenavir capsules.
CONCLUSIONS
Amprenavir-containing combination regimens have shown virological efficacy, and have generally been well tolerated, in patients with HIV infection (primarily treatment-naive or protease inhibitor-naive). The limited number of studies available and the absence of well controlled comparisons with other triple therapies limits the conclusions that can be drawn at present. The clinical value of amprenavir for patients with isolates which are resistant to other protease inhibitors but sensitive to amprenavir, and in treatment-experienced patients in general, requires further investigation. Further evaluation of the amprenavir/ritonavir combination is awaited with interest. Like other members of its class, amprenavir has a particular profile of tolerability, resistance and administration characteristics which should be carefully considered in relation to the needs of individual patients.
Topics: Animals; Carbamates; Clinical Trials, Phase III as Topic; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Molecular Structure; Randomized Controlled Trials as Topic; Sulfonamides; Treatment Outcome
PubMed: 11152018
DOI: 10.2165/00003495-200060060-00012 -
Drugs 2005Amprenavir is an HIV-1 protease inhibitor, the first in vitro activity studies of which were published in 1995. During in vivo development, it became clear that the... (Review)
Review
Amprenavir is an HIV-1 protease inhibitor, the first in vitro activity studies of which were published in 1995. During in vivo development, it became clear that the pharmacokinetics of the drug would result in patients taking a large number of pills daily. The first comparative studies of amprenavir versus other protease inhibitors showed it had comparatively weak activity. Thus, studies using low doses of ritonavir to enhance the pharmacokinetic profile of amprenavir were first communicated in 2000. Only a small number of clinical trials in HIV-1-infected patients have been published. The pharmacokinetics of amprenavir have been documented in both healthy individuals and in HIV-1-infected patients. Amprenavir trough plasma concentrations increase 3- to 10-fold and the area under the concentration-time curve (AUC) increases 2- to 3-fold when using amprenavir 450 or 600 mg combined with ritonavir 100mg twice daily. Peak concentrations of amprenavir are less influenced by ritonavir coadministration, with a 1- to 2-fold increase. As there is no pharmacokinetic advantage to increasing ritonavir doses, the combination has only been used with low doses of ritonavir (100mg twice daily or 200 mg once or twice daily). Concomitant use of currently available non-nucleoside reverse transcriptase inhibitors (NNRTIs)--efavirenz or nevirapine--is possible when amprenavir is coadministered with ritonavir, despite the pharmacokinetic interactions described when they are used with amprenavir alone. Fosamprenavir (GW 433908) is a prodrug of amprenavir primarily metabolised to amprenavir in the epithelial cells of the intestine. At steady state, plasma trough concentrations and AUC are slightly greater with fosamprenavir (two pills of 700 mg twice daily) than amprenavir (eight soft gel capsules of 150 mg twice daily). The clinical adverse effects of amprenavir are similar whether administered unboosted or in combination with ritonavir. Skin rashes do not appear to be more frequent. With regard to lipid profiles, the addition of ritonavir to amprenavir induces an increase in cholesterol and triglyceride levels; however, prospective comparative studies are lacking. In short-term prospective trials in antiretroviral-naive individuals, virological suppression with highly active antiretroviral therapy containing amprenavir plus ritonavir is similar to or higher than with unboosted amprenavir, with a smaller pill intake. Few comparative data are available in treatment-experienced patients. In several small studies, different salvage regimens which included amprenavir plus ritonavir achieved undetectable viral levels in half of the patients. Although the I50V amino acid substitution is the key mutation conferring resistance to amprenavir, the accumulation of several mutations is needed to increase the IC50 (concentration that produces 50% inhibition) of amprenavir. When used with ritonavir, the accumulation of six or more mutations among L10F/I/V, K20M/R, E35D, R41K, I54V, L63P, V82A/F/T/S and I84V leads to clear decrease in viral response to treatment. In salvage regimens, coadministration of amprenavir with lopinavir/ritonavir induces variations in lopinavir and amprenavir concentrations (decrease or increase in both drug concentrations) compared with the combination with ritonavir alone. Currently, close pharmacokinetic follow-up is mandatory when such combinations are used. There are sufficient data available today to support coadministration of reduced doses of amprenavir with low doses of ritonavir. Compared with amprenavir alone, this results in the administration of fewer pills with equivalent or higher efficacy, but without new clinical adverse effects. The concentrations of amprenavir achieved are high enough for use in treatment-experienced patients who have an accumulation of amino acid substitutions in the HIV-1 protease gene. It also allows combinations with NNRTIs. The pharmacokinetic properties of fosamprenavir and the first clinical trials in treatment-naive and treatment-experienced patients should allow it to be considered as a better alternative to amprenavir in countries where fosamprenavir is already available.
Topics: Anti-HIV Agents; Carbamates; Drug Resistance; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Organophosphates; Ritonavir; Sulfonamides
PubMed: 15748098
DOI: 10.2165/00003495-200565050-00005 -
Clinical Therapeutics May 2000This paper reviews the pharmacologic properties and clinical usefulness of amprenavir, a new human immunodeficiency virus type 1 (HIV-1) protease inhibitor. (Review)
Review
OBJECTIVE
This paper reviews the pharmacologic properties and clinical usefulness of amprenavir, a new human immunodeficiency virus type 1 (HIV-1) protease inhibitor.
BACKGROUND
Amprenavir, the most recent HIV-1 protease inhibitor to receive marketing approval from the US Food and Drug Administration, is a potent competitive inhibitor of HIV-1 protease and a relatively weak inhibitor of HIV-2 protease. Inhibition of the HIV-1 protease enzyme results in immature and noninfectious viral particles. Amprenavir is rapidly absorbed following oral administration. The time to peak concentration (Tmax) in adults is between 1 and 2 hours, the area under the plasma concentration versus time curve is roughly proportional to the dose, the half-life is approximately 8 hours, and the volume of distribution is approximately 430 L. The Tmax in children 4 to 12 years of age is between 1.1 and 1.4 hours. The bioavailability of the solution is 86% relative to the capsule formulation. It is metabolized by the cytochrome P-450 isozyme CYP3A4 and to a lesser extent by CYP2D6 and CYP2C9.
METHODS
We searched MEDLINE (1966 to January 2000), AIDSLINE (1980 to January 2000), International Pharmaceutical Abstracts (1970 to January 2000), PharmaProjects (January 2000 version), and Web sites of major HIV/acquired immunodeficiency syndrome conferences for appropriate published references (1996 to February 2000).
RESULTS
Data reported to date indicate that amprenavir is efficacious in the treatment of HIV disease in patients with primary HIV infection, antiretroviral-naïve patients, protease inhibitor-naïve patients, protease inhibitor-experienced patients, and pediatric patients. Adverse effects were usually of early onset (range, 2 to 21 days) and transient (range, 3 to 46 days), although the incidence of metabolic abnormalities such as lipodystrophy, hyperlipidemia, and diabetes mellitus has not yet been defined. Amprenavir should be avoided in patients with a known sulfonamide allergy. Concomitant use of other medications that are CYP3A4 inducers or inhibitors should be done cautiously and only if the potential benefit clearly outweighs potential risk. The dose should be reduced in patients with significant hepatic impairment (Child-Pugh score, > or = 5). Amprenavir probably should not be administered with rifabutin, rifampin, astemizole, midazolam , triazolam, bepridil, dihydroergotamine, ergotamine, or cisapride. The recommended adult dose is 1200 mg twice daily. For patients between 4 and 12 years of age or between 13 and 16 years of age who weigh < 50 kg, the recommended dosage of the capsule form is 20 mg/kg (22.5 mg/kg for oral solution) twice daily or 15 mg/kg (17 mg/kg for oral solution) 3 times a day to a maximum dose of 2400 mg (2800 mg for oral solution). Patients should not take vitamin E supplements because amprenavir is formulated with a large amount of vitamin E (109 IU/capsule and 46 IU/mL oral solution) to improve oral absorption. Amprenavir may be administered with or without food, but a high-fat meal (> 67 g fat) should be avoided.
CONCLUSIONS
Published clinical data are limited, but amprenavir appears to be efficacious and generally well tolerated in patients with HIV infection. Pharmacoeconomic data are not yet available. The introduction of amprenavir appears to be important, since it provides an additional treatment option as a component of both initial and salvage combination therapies for patients with HIV.
Topics: Anti-HIV Agents; Carbamates; Clinical Trials as Topic; Furans; HIV Protease Inhibitors; Humans; Sulfonamides
PubMed: 10868554
DOI: 10.1016/S0149-2918(00)80044-2 -
Laryngoscope Investigative... Aug 2023Laryngopharyngeal reflux (LPR) causes chronic cough, throat clearing, hoarseness, and dysphagia and can promote laryngeal carcinogenesis. More than 20% of the US...
BACKGROUND
Laryngopharyngeal reflux (LPR) causes chronic cough, throat clearing, hoarseness, and dysphagia and can promote laryngeal carcinogenesis. More than 20% of the US population suffers from LPR and there is no effective medical therapy. Pepsin is a predominant source of damage during LPR which disrupts laryngeal barrier function potentially via E-cadherin cleavage proteolysis and downstream matrix metalloproteinase (MMP) dysregulation. Fosamprenavir (FDA-approved HIV therapeutic and prodrug of amprenavir) is a pepsin-inhibiting LPR therapeutic candidate shown to rescue damage in an LPR mouse model. This study aimed to examine amprenavir protection against laryngeal monolayer disruption and related E-cadherin proteolysis and MMP dysregulation in vitro.
METHODS
Laryngeal (TVC HPV) cells were exposed to buffered saline, pH 7.4 or pH 4 ± 1 mg/mL pepsin ± amprenavir (10-60 min). Analysis was performed by microscopy, Western blot, and real time polymerase chain reaction (qPCR).
RESULTS
Amprenavir (1 μM) rescued pepsin acid-mediated cell dissociation ( < .05). Pepsin acid caused E-cadherin cleavage indicative of regulated intramembrane proteolysis (RIP) and increased 24-h postexposure ( < .05). Acid alone did not cause cell dissociation or E-cadherin cleavage. Amprenavir (10 μM) protected against E-cadherin cleavage and induction ( < .05).
CONCLUSIONS
Amprenavir, at serum concentrations achievable provided the manufacturer's recommended dose of fosamprenavir for HIV, protects against pepsin-mediated cell dissociation, E-cadherin cleavage, and MMP dysregulation thought to contribute to barrier dysfunction and related symptoms during LPR. Fosamprenavir to amprenavir conversion by laryngeal epithelia, serum and saliva, and relative drug efficacies in an LPR mouse model are under investigation to inform development of inhaled formulations for LPR.
PubMed: 37621274
DOI: 10.1002/lio2.1102 -
The Annals of Pharmacotherapy Jan 2002To review the pharmacokinetics, pharmacodynamics, drug interactions, and dosage and administration information of amprenavir. (Review)
Review
OBJECTIVE
To review the pharmacokinetics, pharmacodynamics, drug interactions, and dosage and administration information of amprenavir.
DATA SOURCE
An extensive review of the literature (MEDLINE search from 1994 to April 2001) relating to the clinical pharmacology of the HIV protease inhibitors was conducted. Meeting abstracts or full presentations and data submitted to the Food and Drug Administration were also reviewed.
STUDY SELECTION AND DATA EXTRACTION
The data on pharmacokinetics, pharmacodynamics, drug interactions, and drug resistance were obtained from in vitro studies and open-label and controlled clinical trials.
DATA SYNTHESIS
Like all HIV protease inhibitors, amprenavir interrupts the maturation phase of the HIV replicative cycle by forming an inhibitor-enzyme complex, which prevents HIV protease from binding with its normal substrates (biologically inactive viral polyproteins). Amprenavir has an enzyme inhibition constant (Ki = 0.6 nM) that falls within the Ki range of the other protease inhibitors. Amprenavir's in vitro 50% inhibitory concentration (IC50) against wild-type clinical HIV isolates is 14.6 +/- 12.5 ng/mL (mean +/- SD). Pharmacodynamic modeling indicates that, as is the case with other protease inhibitors, the concentration-response curve for amprenavir plateaus at amprenavir trough values above the IC50 for these isolates. This exposure-activity relationship, plus such favorable pharmacokinetic parameters as a long terminal elimination half-life (7-10 h), makes amprenavir an attractive drug of choice when considering potent antiretrovirals. The higher trough exposure obtained with amprenavir coadministered with ritonavir may allow effective treatment of patients with decreased susceptibility viral isolates and once-daily dosing. Amprenavir has been approved for adults and children; the recommended capsule doses are 1200 mg twice daily for adults and 20 mg/kg twice daily or 15 mg/kg 3 times daily for children < 13 years of age or adolescents < 50 kg. The recommended dose for amprenavir oral solution is 1.5 mL/kg twice daily or 1.1 mL/kg 3 times daily.
CONCLUSIONS
The clinical pharmacology, exposure-activity relationship, and drug resistance profile of amprenavir support the use of this potent HIV protease inhibitor in combination antiretroviral regimens, especially for persons who have experienced virologic failure while on protease inhibitor-containing regimens.
Topics: Carbamates; Drug Interactions; Female; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Male; Sulfonamides; Tissue Distribution
PubMed: 11816239
DOI: 10.1345/aph.10423 -
International Journal of Clinical... Jun 1999Amprenavir is a new peptidomimetic inhibitor of the HIV protease enzyme. Amprenavir has a twice daily dosing schedule and can be administered with or without food making... (Review)
Review
Amprenavir is a new peptidomimetic inhibitor of the HIV protease enzyme. Amprenavir has a twice daily dosing schedule and can be administered with or without food making it a convenient dosing regimen among the protease inhibitors (PIs). It is currently being investigated in combination with various nucleoside reverse transcriptase inhibitors (NRTIs) and initial results are promising. Amprenavir may also be useful for salvage therapy in patients failing PI-containing regimens as little cross-resistance has been observed so far with nelfinavir, indinavir or saquinavir. However, amprenavir resistant strains show cross-resistance with ritonavir. Clinical evidence indicates amprenavir is generally well tolerated. However, there is little information to date regarding the ability of amprenavir to cause lipodystrophy or other disturbances of lipid metabolism.
Topics: Anti-HIV Agents; Carbamates; Drug Resistance, Microbial; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Sulfonamides
PubMed: 10622044
DOI: No ID Found -
International Journal of Molecular... Apr 2023Gastroesophageal reflux disease (GERD) significantly impacts patient quality of life and is a major risk factor for the development of Barrett's esophagus (BE) and...
Gastroesophageal reflux disease (GERD) significantly impacts patient quality of life and is a major risk factor for the development of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). Proton pump inhibitors (PPIs) are the standard-of-care for GERD and are among the most prescribed drugs in the world, but do not protect against nonacid components of reflux such as pepsin, or prevent reflux-associated carcinogenesis. We recently identified an HIV protease inhibitor amprenavir that inhibits pepsin and demonstrated the antireflux therapeutic potential of its prodrug fosamprenavir in a mouse model of laryngopharyngeal reflux. In this study, we assessed the capacity of amprenavir to protect against esophageal epithelial barrier disruption in vitro and related molecular events, E-cadherin cleavage, and matrix metalloproteinase induction, which are associated with GERD severity and esophageal cancer. Herein, weakly acidified pepsin (though not acid alone) caused cell dissociation accompanied by regulated intramembrane proteolysis of E-cadherin. Soluble E-cadherin responsive matrix metalloproteinases (MMPs) were transcriptionally upregulated 24 h post-treatment. Amprenavir, at serum concentrations achievable given the manufacturer-recommended dose of fosamprenavir, protected against pepsin-induced cell dissociation, E-cadherin cleavage, and MMP induction. These results support a potential therapeutic role for amprenavir in GERD recalcitrant to PPI therapy and for preventing GERD-associated neoplastic changes.
Topics: Animals; Mice; Pepsin A; Protease Inhibitors; Quality of Life; Esophageal Neoplasms; Enzyme Inhibitors; Laryngopharyngeal Reflux; Proton Pump Inhibitors
PubMed: 37047737
DOI: 10.3390/ijms24076765 -
Clinical Pharmacokinetics 2006Fosamprenavir is one of the most recently approved HIV-1 protease inhibitors (PIs) and offers reductions in pill number and pill size, and omits the need for food and... (Review)
Review
Fosamprenavir is one of the most recently approved HIV-1 protease inhibitors (PIs) and offers reductions in pill number and pill size, and omits the need for food and fluid requirements associated with the earlier-approved HIV-1 PIs. Three fosamprenavir dosage regimens are approved by the US FDA for the treatment of HIV-1 PI-naive patients, including fosamprenavir 1,400 mg twice daily, fosamprenavir 1,400 mg once daily plus ritonavir 200mg once daily, and fosamprenavir 700 mg twice daily plus ritonavir 100mg twice daily. Coadministration of fosamprenavir with ritonavir significantly increases plasma amprenavir exposure. The fosamprenavir 700 mg twice daily plus ritonavir 100mg twice daily regimen maintains the highest plasma amprenavir concentrations throughout the dosing interval; this is the only approved regimen for the treatment of HIV-1 PI-experienced patients and is the only regimen approved in the European Union. Fosamprenavir is the phosphate ester prodrug of the HIV-1 PI amprenavir, and is rapidly and extensively converted to amprenavir after oral administration. Plasma amprenavir concentrations are quantifiable within 15 minutes of dosing and peak at 1.5-2 hours after fosamprenavir dosing. Food does not affect the absorption of amprenavir following administration of the fosamprenavir tablet formulation; therefore, fosamprenavir tablets may be administered without regard to food intake. Amprenavir has a large volume of distribution, is 90% bound to plasma proteins and is a substrate of P-glycoprotein. With <1% of a dose excreted in urine, the renal route is not an important elimination pathway, while the principal route of amprenavir elimination is hepatic metabolism by cytochrome P450 (CYP) 3A4. Amprenavir is also an inhibitor and inducer of CYP3A4. Furthermore, fosamprenavir is commonly administered in combination with low-dose ritonavir, which is also extensively metabolised by CYP3A4, and is a more potent CYP3A4 inhibitor than amprenavir. This potent CYP3A4 inhibition contraindicates the coadministration of certain CYP3A4 substrates and requires others to be co-administered with caution. However, fosamprenavir can be co-administered with many other antiretroviral agents, including drugs of the nucleoside/nucleotide reverse transcriptase inhibitor, non-nucleoside reverse transcriptase inhibitor and HIV entry inhibitor classes. Coadministration with other HIV-1 PIs continues to be studied.The extensive fosamprenavir and amprenavir clinical drug interaction information provides guidance on how to co-administer fosamprenavir and fosamprenavir plus ritonavir with many other commonly co-prescribed medications, such as gastric acid suppressants, HMG-CoA reductase inhibitors, antibacterials and antifungal agents.
Topics: Adult; Carbamates; Drug Interactions; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Half-Life; Humans; Intestinal Absorption; Organophosphates; Prodrugs; Reverse Transcriptase Inhibitors; Sulfonamides; Tissue Distribution
PubMed: 16485915
DOI: 10.2165/00003088-200645020-00002