| Medicinal products by therapeutic area | Interaction | Recommendations concerning co-administration |
| ANTI-RETROVIRALS |
| Protease inhibitors:
The co-administration of REYATAZ/ritonavir and other protease inhibitors has not been studied but would be expected to increase exposure to other protease inhibitors. Therefore, such co-administration is not recommended.
|
| Ritonavir 100 mg once daily(atazanavir 300 mg once daily)
Studies conducted in HIV-infected patients.
| Atazanavir AUC: ↑250% (↑144% ↑403%)*
Atazanavir Cmax: ↑120% (↑56% ↑211%)*
Atazanavir Cmin: ↑713% (↑359% ↑1339%)*
* In a combined analysis, atazanavir 300 mg and ritonavir 100 mg (n=33) was compared to atazanavir 400 mg without ritonavir (n=28).
The mechanism of interaction between atazanavir and ritonavir is CYP3A4 inhibition.
| Ritonavir 100 mg once daily is used as a booster of atazanavir pharmacokinetics.
|
| Indinavir | Indinavir is associated with indirect unconjugated hyperbilirubinaemia due to inhibition of UGT.
| Co-administration of REYATAZ/ritonavir and indinavir is not recommended (see section 4.4).
|
| Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) |
| Lamivudine 150 mg twice daily + zidovudine 300 mg twice daily(atazanavir 400 mg once daily)
| No significant effect on lamivudine and zidovudine concentrations was observed.
| Based on these data and because ritonavir is not expected to have a significant impact on the pharmacokinetics of NRTIs, the co-administration of REYATAZ/ritonavir with these medicinal products is not expected to significantly alter the exposure of the co-administered drugs.
|
| Abacavir | The co-administration of REYATAZ/ ritonavir with abacavir is not expected to significantly alter the exposure of abacavir.
| |
| Didanosine (buffered tablets) 200 mg/stavudine 40 mg, both single dose(atazanavir 400 mg single dose)
| Atazanavir, simultaneous administration with ddI+d4T (fasted)
Atazanavir AUC 87% ( 92% 79%)
Atazanavir Cmax 89% ( 94% 82%)
Atazanavir Cmin 84% ( 90% 73%)
Atazanavir, dosed 1 hr after ddI+d4T (fasted)
Atazanavir AUC ↔3% ( 36% ↑67%)
Atazanavir Cmax↑12% ( 33% ↑18%)
Atazanavir Cmin ↔3% ( 39% ↑73%)
Atazanavir concentrations were greatly decreased when co-administered with didanosine (buffered tablets) and stavudine. The mechanism of interaction is a reduced solubility of atazanavir with increasing pH related to the presence of anti-acid agent in didanosine buffered tablets.
No significant effect on didanosine and stavudine concentrations was observed.
| Didanosine should be taken at the fasted state 2 hours after REYATAZ/ritonavir taken with food. The co-administration of REYATAZ/ritonavir with stavudine is not expected to significantly alter the exposure of stavudine.
|
| Didanosine (enteric coated capsules) 400 mg single dose(atazanavir 300 mg once daily with ritonavir 100 mg once daily)
| Didanosine (with food)
Didanosine AUC 34% ( 41% 27%)
Didanosine Cmax 38% ( 48% 26%)
Didanosine Cmin↑25% ( 8% ↑69%)
No significant effect on atazanavir concentrations was observed when administered with enteric-coated didanosine, but administration with food decreased didanosine concentrations.
|
| Tenofovir disoproxil fumarate 300 mg once daily(atazanavir 300 mg once daily with ritonavir 100 mg once daily)
Studies conducted in HIV-infected patients
| Atazanavir AUC 22% ( 35% 6%) *
Atazanavir Cmax 16% ( 30% ↔0%) *
Atazanavir Cmin 23% ( 43% ↑2%) *
* In a combined analysis from several clinical studies, atazanavir/ritonavir 300/100 mg co-administered with tenofovir disoproxil fumarate 300 mg (n=39) was compared to atazanavir/ritonavir 300/100 mg (n=33).
The efficacy of REYATAZ/ritonavir in combination with tenofovir in treatment-experienced patients has been demonstrated in clinical study 045 and in treatment naive patients in clinical study 138 (see sections 4.8 and 5.1). The mechanism of interaction between atazanavir and tenofovir is unknown.
| |
| Tenofovir disoproxil fumarate 300 mg once daily(atazanavir 300 mg once daily with ritonavir 100 mg once daily)
| Tenofovir disoproxil fumarate AUC ↑37% (↑30% ↑45%)
Tenofovir disoproxil fumarate Cmax↑34% (↑20% ↑51%)
Tenofovir disoproxil fumarate Cmin↑29% (↑21% ↑36%)
| Patients should be closely monitored for tenofovir-associated adverse events, including renal disorders.
|
| Non-nucleoside reverse transcriptase inhibitors (NNRTIs) |
| Efavirenz 600 mg once daily(atazanavir 400 mg once daily with ritonavir 100 mg once daily)
| Atazanavir (pm): all administered with food
Atazanavir AUC ↔0%( 9% ↑10%)*
Atazanavir Cmax↑17%(↑8% ↑27%)*
Atazanavir Cmin 42%( 51% 31%)*
| Co-administration of efavirenz with REYATAZ/ritonavir is not recommended (see section 4.4)
|
| Efavirenz 600 mg once daily(atazanavir 400 mg once daily with ritonavir 200 mg once daily)
| Atazanavir (pm): all administered with food
Atazanavir AUC ↔6% ( 10% ↑26%) */**
Atazanavir Cmax ↔9% ( 5% ↑26%) */**
Atazanavir Cmin ↔12% ( 16% ↑49%) */**
* When compared to REYATAZ 300 mg/ritonavir 100 mg once daily in the evening without efavirenz. This decrease in atazanavir Cmin, might negatively impact the efficacy of atazanavir. The mechanism of efavirenz/atazanavir interaction is CYP3A4 induction.
** Based on historical comparison.
|
| Nevirapine 200 mg twice daily(atazanavir 400 mg once daily with ritonavir 100 mg once daily)
Study conducted in HIV infected patients
| Nevirapine AUC ↑26% (↑17% ↑36%)
Nevirapine Cmax↑21% (↑11% ↑32%)
Nevirapine Cmin↑35% (↑25% ↑47%)
Atazanavir AUC 19% ( 35% ↑2%) *
Atazanavir Cmax ↔2% ( 15% ↑24%) *
Atazanavir Cmin 59% ( 73% 40%) *
* When compared to REYATAZ 300 mg and ritonavir 100 mg without nevirapine. This decrease in atazanavir Cmin, might negatively impact the efficacy of atazanavir. The mechanism of nevirapine/atazanavir interaction is CYP3A4 induction.
| Co-administration of nevirapine with REYATAZ/ritonavir is not recommended (see section 4.4)
|
| Integrase Inhibitors |
| Raltegravir 400 mg twice daily(atazanavir/ritonavir)
| Raltegravir AUC↑ 41%
Raltegravir Cmax ↑ 24%
Raltegravir C12hr ↑ 77%
The mechanism is UGT1A1 inhibition.
| No dose adjustment required for Isentress.
|
| ANTIBIOTICS |
| Clarithromycin 500 mg twice daily(atazanavir 400 mg once daily)
| Clarithromycin AUC ↑94% (↑75% ↑116%)
Clarithromycin Cmax↑50% (↑32% ↑71%)
Clarithromycin Cmin↑160% (↑135% ↑188%)
14-OH clarithromycin
14-OH clarithromycin AUC 70% ( 74% 66%)
14-OH clarithromycin Cmax 72% ( 76% 67%)
14-OH clarithromycin Cmin 62% ( 66% 58%)
Atazanavir AUC ↑28% (↑16% ↑43%)
Atazanavir Cmax ↔6% ( 7% ↑20%)
Atazanavir Cmin↑91% (↑66% ↑121%)
A dose reduction of clarithromycin may result in subtherapeutic concentrations of 14-OH clarithromycin. The mechanism of the clarithromycin/atazanavir interaction is CYP3A4 inhibition.
| No recommendation regarding dose reduction can be made; therefore, caution should be exercised if REYATAZ/ritonavir is co-administered with clarithromycin.
|
| ANTIFUNGALS |
| Ketoconazole 200 mg once daily(atazanavir 400 mg once daily)
| No significant effect on atazanavir concentrations was observed.
| Ketoconazole and itraconazole should be used cautiously with REYATAZ/ritonavir. High doses of ketoconazole and itraconazole (>200 mg/day) are not recommended.
|
| Itraconazole | Itraconazole, like ketoconazole, is a potent inhibitor as well as a substrate of CYP3A4.
|
| | Based on data obtained with other boosted PIs and ketoconazole, where ketoconazole AUC showed a 3-fold increase, REYATAZ/ritonavir is expected to increase ketoconazole or itraconazole concentrations.
|
| Voriconazole | Co-administration of REYATAZ/ritonavir and voriconazole has not been studied.
The effect of co-administration of oral voriconazole and low dose (100 mg) oral ritonavir was investigated in healthy volunteers. Low doses of ritonavir (100 mg twice daily) decreased the Cmax and AUC of voriconazole (90% CI) by an average of 24% ( 9% to 36%) and 39% ( 22% to 52%), respectively. Administration of voriconazole resulted in a minor decrease in steady state Cmax and AUC of ritonavir (90% CI) with an average of 24% ( 6% to 39%) and 14% ( 26% to ↑1%), respectively.
| Co-administration of voriconazole and REYATAZ/ritonavir is not recommended unless an assessment of the benefit/risk to the patient justifies the use of voriconazole (see section 4.4). Patients should be carefully monitored for adverse events and/or loss of efficacy during the co-administration of voriconazole and REYATAZ/ritonavir.
|
| Fluconazole 200 mg once daily(atazanavir 300 mg and ritonavir 100 mg once daily)
| Atazanavir and fluconazole concentrations were not significantly modified when REYATAZ/ritonavir was co-administered with fluconazole.
| No dosage adjustments are needed for REYATAZ/ritonavir and fluconazole.
|
| ANTIMYCOBACTERIAL |
| Rifabutin 150 mg twice weekly(atazanavir 300 mg and ritonavir 100 mg once daily)
| Rifabutin AUC ↑48% (↑19% ↑84%) **
Rifabutin Cmax↑149% (↑103% ↑206%) **
Rifabutin Cmin↑40% (↑5% ↑87%) **
25-O-desacetyl-rifabutin AUC ↑990% (↑714% ↑1361%) **
25-O-desacetyl-rifabutin Cmax↑677% (↑513% ↑883%) **
25-O-desacetyl-rifabutin Cmin↑1045% (↑715% ↑1510%) **
** When compared to rifabutin 150 mg once daily alone. Total rifabutin and 25-O-desacetyl-rifabutin AUC ↑119% (↑78% ↑169%).
In previous studies, the pharmacokinetics of atazanavir was not altered by rifabutin.
| When given with REYATAZ/ritonavir, the recommended dose of rifabutin is 150 mg 3 times per week on set days (for example Monday-Wednesday-Friday). Increased monitoring for rifabutin-associated adverse reactions including neutropenia and uveitis is warranted due to an expected increase in exposure to rifabutin. Further dosage reduction of rifabutin to 150 mg twice weekly on set days is recommended for patients in whom the 150 mg dose 3 times per week is not tolerated. It should be kept in mind that the twice weekly dosage of 150 mg may not provide an optimal exposure to rifabutin thus leading to a risk of rifamycin resistance and a treatment failure. No dose adjustment is needed for REYATAZ/ritonavir.
|
| Rifampicin | Rifampicin is a strong CYP3A4 inducer and has been shown to cause a 72% decrease in atazanavir AUC which can result in virological failure and resistance development. During attempts to overcome the decreased exposure by increasing the dose of REYATAZ or other protease inhibitors with ritonavir, a high frequency of liver reactions was seen.
| The combination of rifampicin and REYATAZ with concomitant low-dose ritonavir is contraindicated (see section 4.3).
|
| ACID REDUCING AGENTS |
| H2-Receptor antagonists |
| Without Tenofovir |
| In HIV-infected patients with atazanavir/ritonavir at the recommended dose 300/100 mg once daily | For patients not taking tenofovir,
if REYATAZ 300 mg/ritonavir 100 mg and H2-receptor antagonists are co-administered, a dose equivalent to famotidine 20 mg twice daily should not be exceeded. If a higher dose of an H2-receptor antagonist is required (eg, famotidine 40 mg twice daily or equivalent) an increase of the REYATAZ/ritonavir dose from 300/100 mg to 400/100 mg can be considered. |
| Famotidine 20 mg twice daily | Atazanavir AUC 18% ( 25% ↑1%)
Atazanavir Cmax 20% ( 32% 7%)
Atazanavir Cmin ↔1% ( 16% ↑18%)
|
| Famotidine 40 mg twice daily | Atazanavir AUC 23% ( 32% 14%)
Atazanavir Cmax 23% ( 33% 12%)
Atazanavir Cmin 20% ( 31% 8%)
|
| In Healthy volunteers with atazanavir/ritonavir at an increased dose of 400/100 mg once daily
|
| Famotidine 40 mg twice daily | Atazanavir AUC ↔3% ( 14% ↑22%)
Atazanavir Cmax ↔2% ( 13% ↑8%)
Atazanavir Cmin 14% ( 32% ↑8%)
|
| With Tenofovir 300 mg once daily |
| In HIV-infected patients with atazanavir/ritonavir at the recommended dose of 300/100 mg once daily
| For patients who are taking tenofovir,Co-administration of REYATAZ/ritonavir in combination with tenofovir and an H2-receptor antagonist should be avoided (see section 4.4). If the combination of REYATAZ/ritonavir with both tenofovir and an H2-receptor antagonist is judged unavoidable, close clinical monitoring is recommended. A dose increase of REYATAZ to 400 mg with 100 mg of ritonavir may be considered but is still under evaluation.
|
| Famotidine 20 mg twice daily | Atazanavir AUC 21% ( 34% 4%) *
Atazanavir Cmax 21% ( 36% 4%) *
Atazanavir Cmin 19% ( 37% ↑5%) *
|
| Famotidine 40 mg twice daily | Atazanavir AUC 24% ( 36% 11%) *
Atazanavir Cmax 23% ( 36% 8%) *
Atazanavir Cmin 25% ( 47% ↑7%) *
|
| | * When compared to atazanavir 300 mg once daily with ritonavir 100 mg once daily and tenofovir disoproxil fumarate 300 mg all as a single dose with food. When compared to atazanavir 300 mg with ritonavir 100 mg without tenofovir, atazanavir concentrations are expected to be additionally decreased by about 20%.
The mechanism of interaction is decreased solubility of atazanavir as intra-gastric pH increases with H2
blockers.
|
| Proton pump inhibitors |
| Omeprazole 40 mg once daily(atazanavir 400 mg once daily with ritonavir 100 mg once daily)
| Atazanavir (am): 2 hr after omeprazole
Atazanavir AUC 61% ( 65% 55%)
Atazanavir Cmax 66% ( 62% 49%)
Atazanavir Cmin 65% ( 71% 59%)
| Co-administration of REYATAZ/ritonavir with proton pump inhibitors is not recommended. If the combination of REYATAZ/ritonavir with a proton pump inhibitor is judged unavoidable, close clinical monitoring is recommended in combination with an increase in the dose of REYATAZ to 400 mg with 100 mg of ritonavir; doses of proton pump inhibitors comparable to omeprazole 20 mg should not be exceeded (see section 4.4).
|
| Omeprazole 20 mg once daily(atazanavir 400 mg once daily with ritonavir 100 mg once daily)
| Atazanavir (am): 1 hr after omeprazole
Atazanavir AUC 30% ( 43% 14%) *
Atazanavir Cmax 31% ( 42% 17%) *
Atazanavir Cmin 31% ( 46% 12%) *
* When compared to atazanavir 300 mg once daily with ritonavir 100 mg once daily.
The decrease in AUC, Cmax, and Cmin was not mitigated when an increased dose of REYATAZ/ritonavir (400/100 mg once daily) was temporally separated from omeprazole by 12 hours. Although not studied, similar results are expected with other proton pump inhibitors. This decrease in atazanavir exposure might negatively impact the efficacy of atazanavir. The mechanism of interaction is decreased solubility of atazanavir as intra-gastric pH increases with proton pump inhibitors.
|
| Antacids |
| Antacids and medicinal products containing buffers | Reduced plasma concentrations of atazanavir may be the consequence of increased gastric pH if antacids, including buffered medicinal products, are administered with REYATAZ/ritonavir.
| REYATAZ/ritonavir should be administered 2 hours before or 1 hour after antacids or buffered medicinal products.
|
| ALPHA 1-ADRENORECEPTOR ANTAGONIST |
| Alfuzosin | Potential for increased alfuzosin concentrations which can result in hypotension. The mechanism of interaction is CYP3A4 inhibition by atazanavir/ritonavir.
| Co-administration of REYATAZ/ritonavir with alfuzosin is contraindicated (see section 4.3)
|
| ANTICOAGULANTS |
| Warfarin | Co-administration with REYATAZ/ritonavir has the potential to produce a decrease or, less often, an increase in INR (International Normalised Ratio).
| It is recommended that the INR be monitored carefully during treatment with REYATAZ/ritonavir, especially when commencing therapy.
|
| ANTINEOPLASTICS AND IMMUNOSUPRESSANTS |
| Antineoplastics |
| Irinotecan | Atazanavir inhibits UGT and may interfere with the metabolism of irinotecan, resulting in increased irinotecan toxicities.
| If REYATAZ/ritonavir is co-administered with irinotecan, patients should be closely monitored for adverse events related to irinotecan.
|
| Immunosuppressants |
| CyclosporinTacrolimusSirolimus | Concentrations of these immunosuppressants may be increased when co-administered with REYATAZ/ritonavir due to CYP3A4 inhibition.
| More frequent therapeutic concentration monitoring of these medicinal products is recommended until plasma levels have been stabilised.
|
| CARDIOVASCULAR AGENTS |
| Antiarrhythmics |
| Amiodarone, Systemic lidocaine, Quinidine | Concentrations of these antiarrhythmics may be increased when co-administered with REYATAZ/ritonavir. The mechanism of amiodarone or systemic lidocaine/atazanavir interaction is CYP3A inhibition. Quinidine has a narrow therapeutic window and is contraindicated due to potential inhibition of CYP3A by REYATAZ/ritonavir.
| Caution is warranted and therapeutic concentration monitoring is recommended when available. The concomitant use of quinidine is contraindicated (see section 4.3).
|
| Calcium channel blockers |
| Bepridil | REYATAZ/ritonavir should not be used in combination with medicinal products that are substrates of CYP3A4 and have a narrow therapeutic index.
| Co-administration with bepridil is contraindicated (see section 4.3)
|
| Diltiazem 180 mg once daily(atazanavir 400 mg once daily)
| Diltiazem AUC ↑125% (↑109% ↑141%)
Diltiazem Cmax↑98% (↑78% ↑119%)
Diltiazem Cmin↑142% (↑114% ↑173%)
Desacetyl-diltiazem AUC ↑165% (↑145% ↑187%)
Desacetyl-diltiazem Cmax↑172% (↑144% ↑203%)
Desacetyl-diltiazem Cmin↑121% (↑102% ↑142%)
No significant effect on atazanavir concentrations was observed. There was an increase in the maximum PR interval compared to atazanavir alone. Co-administration of diltiazem and REYATAZ/ritonavir has not been studied. The mechanism of diltiazem/atazanavir interaction is CYP3A4 inhibition.
| An initial dose reduction of diltiazem by 50% is recommended, with subsequent titration as needed and ECG monitoring.
|
| Verapamil | Serum concentrations of verapamil may be increased by REYATAZ/ritonavir due to CYP3A4 inhibition.
| Caution should be exercised when verapamil is co-administered with REYATAZ/ritonavir.
|
| CORTICOSTEROIDS |
| Fluticasone propionate intranasal 50 μg 4 times daily for 7 days(ritonavir 100 mg capsules twice daily)
| The fluticasone propionate plasma levels increased significantly, whereas the intrinsic cortisol levels decreased by approximately 86% (90% confidence interval 82%-89%) Greater effects may be expected when fluticasone propionate is inhaled. Systemic corticosteroid effects including Cushing's syndrome and adrenal suppression have been reported in patients receiving ritonavir and inhaled or intranasally administered fluticasone propionate; this could also occur with other corticosteroids metabolized via the P450 3A pathway, e.g., budesonide. The effects of high fluticasone systemic exposure on ritonavir plasma levels are yet unknown. The mechanism of interaction is CYP3A4 inhibition.
| Co-administration of REYATAZ/ritonavir and these glucocorticoids is not recommended unless the potential benefit of treatment outweighs the risk of systemic corticosteroid effects (see section 4.4). A dose reduction of the glucocorticoid should be considered with close monitoring of local and systemic effects or a switch to a glucocorticoid, which is not a substrate for CYP3A4 (e.g., beclomethasone). Moreover, in case of withdrawal of glucocorticoids, progressive dose reduction may have to be performed over a longer period.
|
| ERECTILE DYSFUNCTION |
| PDE5 Inhibitors |
| Sildenafil, tadalafil, vardenafil | Sildenafil, tadalafil, and vardenafil are metabolised by CYP3A4. Co-administration with REYATAZ/ritonavir may result in increased concentrations of the PDE5 inhibitor and an increase in PDE5-associated adverse events, including hypotension, visual changes, and priapism. The mechanism of this interaction is CYP3A4 inhibition.
| Patients should be warned about these possible side effects when using PDE5 inhibitors for erectile dysfunction with REYATAZ/ritonavir (see section 4.4).
Also see PULMONARY ATERIAL HYPERTENSION in this table for futher information regarding co-administration of REYATAZ/ritonavir with sildenafil.
|
| HERBAL PRODUCTS |
| St. John's wort (Hypericum perforatum) | Concomitant use of St. John's wort with REYATAZ/ritonavir may be expected to result in significant reduction in plasma levels of atazanavir. This effect may be due to an induction of CYP3A4. There is a risk of loss of therapeutic effect and development of resistance (see section 4.3).
| Co-administration of REYATAZ/ritonavir with products containing St. John's wort is contraindicated.
|
| HORMONAL CONTRACEPTIVES |
| Ethinyloestradiol 25 μg + norgestimate(atazanavir 300 mg once daily with ritonavir 100 mg once daily)
| Ethinyloestradiol AUC 19% ( 25% 13%)
Ethinyloestradiol Cmax 16% ( 26% 5%)
Ethinyloestradiol Cmin 37% ( 45% 29%)
Norgestimate AUC ↑85% (↑67% ↑105%)
Norgestimate Cmax↑68% (↑51% ↑88%)
Norgestimate Cmin↑102% (↑77% ↑131%)
While the concentration of ethinyloestradiol was increased with atazanavir given alone, due to both UGT and CYP3A4 inhibition by atazanavir, the net effect of atazanavir/ritonavir is a decrease in ethinyloestradiol levels because of the inducing effect of ritonavir.
The increase in progestin exposure may lead to related side-effects (e.g. insulin resistance, dyslipidemia, acne and spotting), thus possibly affecting the compliance.
| If an oral contraceptive is administered with REYATAZ/ritonavir, it is recommended that the oral contraceptive contain at least 30 μg of ethinyloestradiol and that the patient be reminded of strict compliance with this contraceptive dosing regimen. Co-administration of REYATAZ/ritonavir with other hormonal contraceptives or oral contraceptives containing progestogens other than norgestimate has not been studied, and therefore should be avoided. An alternate reliable method of contraception is recommended.
|
| LIPID LOWERING AGENTS |
| HMG-CoA reductase inhibitors |
| SimvastatinLovastatin | Simvastatin and lovastatin are highly dependent on CYP3A4 for their metabolism and co-administration with REYATAZ/ritonavir may result in increased concentrations.
| Co-administration of simvastatin or lovastatin with REYATAZ/ritonavir is not recommended due to an increased risk of myopathy including rhabdomyolysis. The use of another HMG-CoA reductase inhibitor which does not undergo metabolism by CYP3A such as pravastatin or fluvastatin is recommended.
|
| Atorvastatin | The risk of myopathy including rhabdomyolysis may also be increased with atorvastatin, which is also metabolised by CYP3A4.
| Caution should be exercised.
|
| INHALED BETA AGONISTS |
| Salmeterol | Co-administration with REYATAZ/ritonavir may result in increased concentrations of salmeterol and an increase in salmeterol-associated adverse events.
The mechanism of interaction is CYP3A4 inhibition by atazanavir/ritonavir.
| Co-administration of salmeterol with REYATAZ/ritonavir is not recommended (see section 4.4).
|
| OPIOIDS |
| Buprenorphine, once daily, stable maintenance dose(atazanavir 300 mg once daily with ritonavir 100 mg once daily)
| Buprenorphine AUC ↑67%
Buprenorphine Cmax↑37%
Buprenorphine Cmin↑69%
Norbuprenorphine AUC ↑105%
Norbuprenorphine Cmax↑61%
Norbuprenorphine Cmin↑101%
The mechanism of interaction is CYP3A4 and UGT1A1 inhibition.
Concentrations of atazanavir were not significantly affected.
| Co-administration warrants clinical monitoring for sedation and cognitive effects. A dose reduction of buprenorphine may be considered
|
| Methadone, stable maintenance dose(atazanavir 400 mg once daily)
| No significant effect on methadone concentrations was observed. Given that low dose ritonavir (100 mg twice daily) has been shown to have no significant effect on methadone concentrations, no interaction is expected if methadone is co-administered with REYATAZ and ritonavir, based on these data..
| No dosage adjustment is necessary if methadone is co-administered with REYATAZ and ritonavir.
|
| PULMONARY ARTERIAL HYPERTENSION |
| PDE5 Inhibitors |
| Sildenafil | Co-administration with REYATAZ/ritonavir may result in increased concentrations of the PDE5 inhibitor and an increase in PDE5-inhibitor-associated adverse events.
The mechanism of interaction is CYP3A4 inhibition by atazanavir/ritonavir.
| A safe and effective dose in combination with REYATAZ/ritonavir has not been established for sildenafil when used to treat pulmonary arterial hypertension. Sildenafil, when used for the treatment of pulmonary arterial hypertension, is contraindicated (see section 4.3).
|
| SEDATIVES |
| Benzodiazepines |
| MidazolamTriazolam | Midazolam and triazolam are extensively metabolized by CYP3A4. Co-administration with REYATAZ/ritonavir may cause a large increase in the concentration of these benzodiazepines. No drug interaction study has been performed for the co-administration of REYATAZ/ritonavir with benzodiazepines. Based on data for other CYP3A4 inhibitors, plasma concentrations of midazolam are expected to be significantly higher when midazolam is given orally. Data from concomitant use of parenteral midazolam with other protease inhibitors suggest a possible 3-4 fold increase in midazolam plasma levels.
| REYATAZ/ritonavir should not be co-administered with triazolam or orally administered midazolam (see section 4.3), whereas caution should be used with co-administration of REYATAZ/ritonavir and parenteral midazolam. If REYATAZ is co-administered with parenteral midazolam, it should be done in an intensive care unit (ICU) or similar setting which ensures close clinical monitoring and appropriate medical management in case of respiratory depression and/or prolonged sedation. Dosage adjustment for midazolam should be considered, especially if more than a single dose of midazolam is administered.
|