Updated Reviewed

Drug-Drug Interactions

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 judgment 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/NameEffect on gp120-Directed Attachment Inhibitor and/or Concomitant Drug ConcentrationsDosing Recommendations and Clinical Comments
Acid Reducers
H2 Receptor Antagonists↔ TMRNo dose adjustment needed
Anticonvulsants
Carbamazepine, Phenobarbital, Phenytoin↓ TMR expectedContraindicated
Antibacterials—Antimycobacterials 
Rifabutin

With Rifabutin 300 mg Once Daily and Without RTV

  • TMR AUC ↓ 30%

With Rifabutin 150 mg Once Daily and With RTV 100 mg Once Daily

  • TMR AUC ↑ 66%

If Used Without PI/r

  • No dose adjustment needed

If Used With PI/r

  • Recommended dose is rifabutin 150 mg once daily.
  • No dose adjustment of FTR
RifampinTMR AUC ↓ 82%Contraindicated
Rifapentine

Daily and Weekly Dosing

↓ TMR expected

Do not coadminister.
Antivirals—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.
Antivirals—Miscellaneous (e.g., for CMV, 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
Antivirals—SARS-CoV-2
Molnupiravir↔ expectedNo dose adjustment needed
Ritonavir-Boosted NirmatrelvirTMR AUC ↑ 45%No dose adjustment needed
Remdesivir↔ expectedNo dose adjustment needed
Herbal Products
St. John’s Wort↓ TMR expectedContraindicated
Hormonal Therapies
Hormonal Contraceptives

Ethinyl 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 Therapies

(e.g., estradiol, 5-alpha reductase inhibitors, testosterone) 

↑ estradiol possibleUse lowest effective dose for estrogen-containing regimens.

Menopausal Hormone Replacement Therapy

(e.g., conjugated estrogens, drospirenone, estradiol, medroxyprogesterone, progesterone)

↑ estrogens, estradiol possibleUse lowest effective dose for estrogen-containing regimens.
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/Naloxone

Buprenorphine 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 (SQ 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
ETR

TMR AUC ↓ 50%

↔ ETR

No dose adjustment needed
ETR plus DRV/r

TMR Cmax and AUC ↑ 34% to 53%

↔ DRV, RTV

ETR AUC ↑ 28%

No dose adjustment needed
PIs 
ATV/c

↑ TMR expected

↔ ATV expected

No dose adjustment needed
ATV/r

TMR Cmax and AUC ↑ 54% to 58%

↔ ATV, RTV

No dose adjustment needed
DRV/c

TMR Cmax and AUC ↑ 79% to 97%

↔ DRV, RTV expected

No dose adjustment needed
DRV/r

TMR Cmax and AUC ↑ 52% to 63%

↔ DRV, RTV

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
↔ = less than 20% change in AUC

Key: ALT = alanine aminotransferase; ARV = antiretroviral; AST = aspartate aminotransferase; ATV/c = atazanavir/cobicistat; ATV/r = atazanavir/ritonavir; AUC = area under the curve; BIC = bictegravir; Cmax = maximum plasma concentration; CAB = cabotegravir; CCR5 = C-C chemokine receptor type 5; CMV = cytomegalovirus; 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; gp120 = glycoprotein 120; HCV = hepatitis C virus; IBA = ibalizumab; IM = intramuscular; INSTI = integrase strand transfer inhibitor; LEN = lenacapavir; MVC = maraviroc; NNRTI = non-‍nucleoside reverse transcriptase inhibitor; NRTI = nucleoside reverse transcriptase inhibitor; PI = protease inhibitor; PI/r = ritonavir-boosted PI; PO = orally; RAL = raltegravir; RPV = rilpivirine; RTV = ritonavir; SQ = subcutaneous; TDF = tenofovir disoproxil fumarate; TMR = temsavir

Drug-Drug Interactions

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

Concomitant Drug Class/NameEffect on gp120-Directed Attachment Inhibitor and/or Concomitant Drug ConcentrationsDosing Recommendations and Clinical Comments
Acid Reducers
H2 Receptor Antagonists↔ TMRNo dose adjustment needed
Anticonvulsants
Carbamazepine, Phenobarbital, Phenytoin↓ TMR expectedContraindicated
Antibacterials—Antimycobacterials 
Rifabutin

With Rifabutin 300 mg Once Daily and Without RTV

  • TMR AUC ↓ 30%

With Rifabutin 150 mg Once Daily and With RTV 100 mg Once Daily

  • TMR AUC ↑ 66%

If Used Without PI/r

  • No dose adjustment needed

If Used With PI/r

  • Recommended dose is rifabutin 150 mg once daily.
  • No dose adjustment of FTR
RifampinTMR AUC ↓ 82%Contraindicated
Rifapentine

Daily and Weekly Dosing

↓ TMR expected

Do not coadminister.
Antivirals—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.
Antivirals—Miscellaneous (e.g., for CMV, 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
Antivirals—SARS-CoV-2
Molnupiravir↔ expectedNo dose adjustment needed
Ritonavir-Boosted NirmatrelvirTMR AUC ↑ 45%No dose adjustment needed
Remdesivir↔ expectedNo dose adjustment needed
Herbal Products
St. John’s Wort↓ TMR expectedContraindicated
Hormonal Therapies
Hormonal Contraceptives

Ethinyl 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 Therapies

(e.g., estradiol, 5-alpha reductase inhibitors, testosterone) 

↑ estradiol possibleUse lowest effective dose for estrogen-containing regimens.

Menopausal Hormone Replacement Therapy

(e.g., conjugated estrogens, drospirenone, estradiol, medroxyprogesterone, progesterone)

↑ estrogens, estradiol possibleUse lowest effective dose for estrogen-containing regimens.
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/Naloxone

Buprenorphine 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 (SQ 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
ETR

TMR AUC ↓ 50%

↔ ETR

No dose adjustment needed
ETR plus DRV/r

TMR Cmax and AUC ↑ 34% to 53%

↔ DRV, RTV

ETR AUC ↑ 28%

No dose adjustment needed
PIs 
ATV/c

↑ TMR expected

↔ ATV expected

No dose adjustment needed
ATV/r

TMR Cmax and AUC ↑ 54% to 58%

↔ ATV, RTV

No dose adjustment needed
DRV/c

TMR Cmax and AUC ↑ 79% to 97%

↔ DRV, RTV expected

No dose adjustment needed
DRV/r

TMR Cmax and AUC ↑ 52% to 63%

↔ DRV, RTV

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
↔ = less than 20% change in AUC

Key: ALT = alanine aminotransferase; ARV = antiretroviral; AST = aspartate aminotransferase; ATV/c = atazanavir/cobicistat; ATV/r = atazanavir/ritonavir; AUC = area under the curve; BIC = bictegravir; Cmax = maximum plasma concentration; CAB = cabotegravir; CCR5 = C-C chemokine receptor type 5; CMV = cytomegalovirus; 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; gp120 = glycoprotein 120; HCV = hepatitis C virus; IBA = ibalizumab; IM = intramuscular; INSTI = integrase strand transfer inhibitor; LEN = lenacapavir; MVC = maraviroc; NNRTI = non-‍nucleoside reverse transcriptase inhibitor; NRTI = nucleoside reverse transcriptase inhibitor; PI = protease inhibitor; PI/r = ritonavir-boosted PI; PO = orally; RAL = raltegravir; RPV = rilpivirine; RTV = ritonavir; SQ = subcutaneous; TDF = tenofovir disoproxil fumarate; TMR = temsavir

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