Sweet Wormwood

Artemisinin and Artemisia annua extract induce CYP2B6 and CYP3A4 expression via activation of PXR and CAR nuclear receptors. Efavirenz is primarily metabolized by CYP2B6 and CYP3A4; induction leads to accelerated efavirenz clearance and subtherapeutic plasma levels. Lopinavir/ritonavir are substrates and inhibitors of CYP3A4 — artemisinin induction could overcome ritonavir boosting and reduce lopinavir exposure. Subtherapeutic antiretroviral levels risk HIV viral rebound and resistance development. Artemisinin itself undergoes auto-induction, explaining its diminishing efficacy with repeated oral dosing.

Do not combine Artemisia annua preparations with efavirenz or lopinavir/ritonavir-based regimens without virological monitoring. If malaria treatment with artemisinin is required in HIV patients, use ACT preparations under expert guidance and monitor HIV viral load. Allow 2 weeks after artemisinin course before resuming standard ARV dosing assessment.

Artemisinin induces CYP3A4 and CYP2B6 via PXR/CAR activation. Ethinyl estradiol and synthetic progestogens (levonorgestrel, norethisterone, etonogestrel) are primarily metabolized by CYP3A4. Repeated artemisinin dosing accelerates their hepatic metabolism, reducing plasma contraceptive steroid levels. This is analogous to the well-established rifampicin-contraceptive interaction. During malaria treatment courses with Artemisia annua and for several weeks after, contraceptive efficacy may be significantly reduced.

Advise patients using Artemisia annua (therapeutic doses for malaria or other indications) that combined oral contraceptives and progestogen-only implants may become unreliable during use and for at least 4 weeks afterward. Recommend barrier contraception during this period. Document and discuss with prescriber before treatment course.

Artemisia annua extracts irreversibly inhibit CYP3A4 activity (IC50 = 4.93 µM for the methanolic extract) and also induce CYP3A4 via PXR activation with repeated dosing. This dual inhibitory/inductive effect creates complex, unpredictable alterations in tacrolimus and cyclosporine plasma levels — initially potentially inhibitory (raising levels and toxicity risk), then inductive with chronic use (lowering levels and rejection risk). Immune-mediated liver injury studies also suggest worsened hepatotoxicity with compromised immunosuppression.

Contraindicated in solid organ transplant patients without intensive drug level monitoring. Tacrolimus and cyclosporine have extremely narrow therapeutic indices. Any Artemisia annua use must trigger immediate trough level measurements at Days 3, 7, and 14. Dose adjustment is almost certainly required. Inform transplant teams before any artemisia product use.

Artemisinin and related sesquiterpene lactones from Artemisia annua have demonstrated mild antiplatelet properties in preclinical studies. Additionally, CYP3A4 induction by artemisinin could accelerate S-warfarin metabolism (CYP2C9) and R-warfarin metabolism (CYP3A4), potentially reducing anticoagulant effect. However, the complexity of enzyme induction timing (initial inhibition followed by induction) makes the net effect unpredictable, warranting INR monitoring throughout any artemisinin treatment course.

Monitor INR at baseline and at weekly intervals if Artemisia annua is used concurrently with warfarin. Expect possible early increase then subsequent decrease in INR. Counsel patients not to alter warfarin dose independently. Direct oral anticoagulants (DOACs) metabolized by CYP3A4 (rivaroxaban, apixaban) may also be affected.

Artemisinin and artemisinin derivatives have demonstrated blood glucose-lowering activity in preclinical models, including beta-cell regeneration effects in diabetic animal models and insulin secretion promotion. When combined with antidiabetic drugs, additive hypoglycemic effects are theoretically possible. The CYP induction by artemisinin may also alter metabolism of some sulfonylureas (CYP2C9 substrates), potentially reducing their plasma levels.

Monitor blood glucose if patients with diabetes use Artemisia annua for malaria prophylaxis or other conditions alongside antidiabetics. Hypoglycemia risk is low but present. Adjust antidiabetic doses as guided by blood glucose monitoring. Note that sulfonylurea levels may be reduced by CYP2C9 induction.