Adult Antiretroviral Guidelines

US DHHS Guidelines with Australian Commentary

HIV-1 gp120-Directed Attachment Inhibitors

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HIV-1 gp120-Directed Attachment Inhibitors

DHHS Last Updated: May 2023

Table 24f. Drug Interactions Between HIV-1 gp120-Directed Attachment Inhibitors and Other Drugs (Including Antiretroviral Agents)

Fostemsavir (FTR), an HIV-1 gp120-directed attachment inhibitor, is a prodrug of temsavir (TMR). In this table, the effect on gp120-directed attachment inhibitor refers to TMR concentrations. Recommendations for managing a particular drug interaction may differ depending on whether a new antiretroviral (ARV) drug is being initiated in a patient on a stable concomitant medication or whether a new concomitant medication is being initiated in a patient on a stable ARV regimen. The magnitude and significance of drug interactions are difficult to predict when several drugs with competing metabolic pathways are prescribed concomitantly. Providers should exercise their clinical judgement to select the most appropriate alternative medication to use in cases where an interacting drug needs to be replaced with an alternative.

Concomitant Drug Class/ Name
Effect on gp120-Directed Attachment Inhibitor and/or Concomitant Drug Concentrations
Dosing Recommendations and Clinical Comments
Acid Reducers
H2 Receptor Antagonists↔ TMRNo dose adjustment needed.
Anticonvulsants
Carbamazepine, Phenobarbital, Phenytoin↓ TMR expectedContraindicated.
Antibacterials—Antimycobacterials
RifabutinWith Rifabutin 300 mg Once Daily and Without RTV

  • TMR AUC ↓ 30%

If Used without PI/r

  • No dosage adjustment needed.


If Used with PI/r

  • Recommended dose is rifabutin 150 mg once daily.

  • No dosage adjustment of FTR.

RifampinTMR AUC ↓ 72%Contraindicated.
Rifapentine↓ TMR expectedDo not coadminister.
Antivirals - Orthopoxviruses (Smallpox, Mpox)
Brincidofovir↑ brincidofovir possibleGive FTR dose at least 3 hours after administering brincidofovir, and monitor for brincidofovir-related adverse events (i.e., elevations in ALT/AST and bilirubin and GI adverse events).
Cidofovir↔ TMR expectedNo dose adjustment needed.
Tecovirimat↔ TMR expectedNo dose adjustment needed.
Hepatitis C Direct-Acting Antivirals
Elbasvir/Grazoprevir↑ grazoprevir expectedIncreased grazoprevir exposures may increase the risk of ALT elevations. Use an alternative HCV regimen.
Ledipasvir/Sofosbuvir↔ expectedNo dose adjustment needed.
Glecaprevir/Pibrentasvir↔ expectedNo dose adjustment needed.
Sofosbuvir↔ expectedNo dose adjustment needed.
Sofosbuvir/Velpatasvir↔ expectedNo dose adjustment needed.
Sofosbuvir/Velpatasvir/Voxilaprevir↑ voxilaprevir expectedUse an alternative HCV regimen if possible.
Herbal Products
St. John’s Wort↓ TMR expectedContraindicated.
Hormonal Therapies
Contraceptives: Oralethinyl estradiol AUC ↑ 40%
↔ norethindrone
Prescribe oral contraceptive that contains no more than 30 mcg of ethinyl estradiola or use alternative ARV or contraceptive methods.
Gender-Affirming Hormone TherapiesNo dataNo data available to make dose recommendation.
Menopausal Hormone Replacement TherapyNo dataNo data available to make dose recommendation.
Lipid-Modifying Agents
Atorvastatin, Fluvastatin, Pitavastatin, Simvastatin↑ statin possible
↔ expected
Increased statin concentration may not be clinically relevant. Follow clinical guidelines. Administer the lowest effective statin dose while monitoring for adverse events.
RosuvastatinRosuvastatin AUC ↑ 69%Increased rosuvastatin concentration may not be clinically relevant. Follow clinical guidelines. Administer the lowest effective dose while monitoring for adverse events.
Narcotics and Treatment for Opioid Dependence
Buprenorphine/NaloxoneBuprenorphine AUC ↑ 30%
Norbuprenorphine (active metabolite) AUC ↑ 39%
No dose adjustment needed.
Methadone↔ Total methadone
↔ R(−) methadone (active metabolite)
↔ S(+) methadone
No dose adjustment needed.
Antiretroviral Drugs
Capsid Inhibitor
LEN (IM and PO)↔ TMR expected
↔ LEN expected
No dose adjustment needed.
CCR5 Antagonist
MVC↔ TMR
MVC AUC ↑ 25%
No dose adjustment needed.
CD4 Post Attachment Inhibitor
IBA↔ expectedNo dose adjustment needed.
INSTIs
BIC, CAB (IM and PO), DTG, EVG/c↔ TMR expectedNo dose adjustment needed.
RAL plus TDF↔ TMRNo dose adjustment needed.
NRTIs
TDF↔ TMR
↔ TDF
No dose adjustment needed.
NNRTIs
DOR, RPV (IM and PO)↔ TMR expectedNo dose adjustment needed.
EFV↓ TMR possible
↔ EFV expected
No dose adjustment needed.
ETRTMR AUC ↓ 50%
↔ ETR
No dose adjustment needed.
ETR plus DRV/rTMR Cmax and AUC ↑ 34% to 53%
↔ DRV, RTV
ETR AUC ↑ 28%
No dose adjustment needed.
PIs
ATV Unboosted, ATV/c↑ TMR possible
↔ ATV expected
No dose adjustment needed.
AATV/rTMR Cmax and AUC ↑ 54% to 58%
↔ ATV, RTV
No dose adjustment needed.
DRV/cTMR Cmax and AUC ↑ 79% to 97%
↔ DRV, RTV expected
No dose adjustment needed.
DRV/rTMR Cmax and AUC ↑ 52% to 63%
↔ DRV, RTV
No dose adjustment needed.
LPV/r↑ TMR possible
↔ LPV expected
No dose adjustment needed.
a The following products contain no more than 30 mcg of ethinyl estradiol combined with norethindrone or norgestimate: Lo Minastrin Fe; Lo Loestrin Fe; Loestrin 1/20, 1.5/30; Loestrin Fe 1/20, 1.5/30; Loestrin 24 Fe; Minastrin 24 Fe; Ortho Tri-Cyclen Lo. Generic formulations also may be available.

Key to Symbols:
↑ = increase
↓ = decrease
↔ = no change

Key: ALT = alanine aminotransferase; ARV = antiretroviral; AST = aspartate aminotransferase; ATV = atazanavir; ATV/c = atazanavir/cobicistat; ATV/r = atazanavir/ritonavir; AUC = area under the curve; BIC = bictegravir; Cmax = maximum plasma concentration; CAB = cabotegravir; DOR = doravirine; DRV = darunavir; DRV/c = darunavir/cobicistat; DRV/r = darunavir/ritonavir; DTG = dolutegravir; EFV = efavirenz; ETR = etravirine; EVG/c = elvitegravir/cobicistat; FTR = fostemsavir; GI = gastrointestinal; INSTI = integrase strand transfer inhibitor; HCV = hepatitis C virus; IM = intramuscular; LEN = lenacapavir; LPV = lopinavir; LPV/r = lopinavir/ritonavir; MVC = maraviroc; NNRTI = non-nucleoside reverse transcriptase inhibitor; NRTI = nucleoside reverse transcriptase inhibitor; PI = protease
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