Elvitegravir / Cobicistat

Carbamazepine

Contraindicated.

No pharmaceutical opinion available for this interaction.

Mechanism

Carbamazepine can induce the metabolism (CYP 3A4) and decrease the plasma concentration of Elvitegravir / Cobicistat.

Elvitegravir / Cobicistat may possibly inhibit the metabolism (CYP 3A4) and consequently increase the plasma concentration of Carbamazepine.

Elvitegravir / Cobicistat

Pharmacodynamic effects

Risk of a possible development of resistance to antiretroviral class.

Possible decrease of clinical efficacy.

Recommendations

Monitor for signs and symptoms of therapeutic failure.

Alternative solution(s)

Carbamazepine

Pharmacodynamic effects

Possible increase of adverse effects.

Recommendations

Contraindicated. Use alternative.

Alternative solution(s)

As clinically indicated : brivaracetam, gabapentin, lacosamide, lamotrigine, levetiracetam, pregabalin, rufinamide, topiramate, vigabatrin, zonisamide.

Monitor

Carbamazepine adverse effects : disorientation, ataxia, lethargy, drowsiness, nausea, vomiting, headache, diplopia, dizziness, leukopenia and hyponatremia.

Tests

Carbamazepine

Viral Load

CD4+

Elvitegravir plasma level

Pharmacokinetic parameters
Parameters
Reference number
# patients
HIV
Dose
Frequency
Duration (days)
AUC
Cmax
Cmin
Elvitegravir / Cobicistat
3069
12
-
150/150 mg
QD
10
- 69%/- 84%
- 97%/- 90%
- 45%/- 72%
Carbamazepine
3069
12
-
200 mg
BID
10
+ 43% *
+ 51% *
+ 40% *
Comment

Ref #3069 : * Carbamazepine10,11-epoxyde AUC -35%, Cmax -41% and Cmin -27%.
Importantly, elvitegravir Cmin, the parameter best associated with antiviral activity, was below the IC95 (45 ng/mL) in 11 of 12 subjects. These study findings are consistent with the current dosing recommendation that carbamazepin be avoided with elvitegravir and cobicistat containing regimens.

Ref #1304 : Reported case of a 20-year-old patient who developed vomiting, dizziness, elevated liver enzymes, and increased carbamazepine concentration by 87% following the addition of one dose of ritonavir 200 mg. Symptoms started within 12 hours after the first dose of ritonavir. In order to obtain a concentration within the therapeutic index, the dose of carbamazepine was reduced from 750 to 280 mg QD. Several other cases of acute toxicity to carbamazepine 2 to 4 days after the addition of ritonavir have been reported. See ritonavir + carbamazepine.

Ref #2090: Another case reported of a 50 year man who developed excessive drowsiness following the introduction of lopinavir/ritonavir and it was found that his serum carbamazepine concentration had increased by 46%. His antiretroviral therapy was then changed to nelfinavir 1250 mg BID but 3 days later the same symptoms appeared with 53% increase in carbamazepine. The symptoms of carbamazepine toxicity disappeared after a carbamazepine dose reduction of 33%. See lopinavir/ritonavir + carbamazepine.

Reference
  • 2570
    Elvitegravir/cobicistat/emtricitabine/tenofovir (Stribild), Gilead, Ontario, Canada, 17 septembre 2018.
  • 2988
    Carbamazepine (Tegretol), Novartis Pharma, Québec, Canada, 4 mai 2018.
  • 3069
    Custodio JM, Shao Y, Begley R, Graham H, Vesterdahl A et al. Pharmacokinetics and Drug Interaction Profile of Cobicistat Boosted-Elvitegravir with Carbamazepine. 54th Interscience Conference on Antimicrobial Agents & Chemotherapy (ICAAC), Washington DC USA, 5-9 sept 2014. Abstract H-1011.
  • 717
    Mateu-de Antonio J, Grau S, Gimeno-Bayon JL, Carmona A. Ritonavir-induced carbamazepine toxicity. Ann Pharmcother 2001;35:125-126.
  • 1304
    Kato Y, Fujii T, Mizoguchi N, et al. Potential interaction between ritonavir and carbamazepine. Pharmacother 2000;20(7):851-854.
  • 1312
    Garcia AB, Ibarra AL, Etessam JP, et al. Protease inhibitor-induced carbamazepine toxicity. Clin Neuropharmacol 2000;23(4):216-218.
  • 1599
    Liedtke MD, Lockhart SM, and Rathbun RC. Anticonvulsivant and antiretroviral interactions. Ann Pharmacother 2004;38:482-489.
  • 2090
    Bates D and Herman RJ. Carbamazepine Toxicity Induced by Lopinavir/Ritonavir and Nelfinavir. Ann Pharmacother 2006;40:1190-1195.
  • 3281
    Elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (Genvoya), Gilead, Ontario, Canada, 6 août 2021.