Andrographis

Andrographolide, the major diterpenoid of Andrographis paniculata, significantly increases systemic warfarin exposure in rats when co-administered (30 mg/kg/day andrographolide for 7 days prior to warfarin 0.5 mg/kg). The mechanism involves inhibition of CYP2C9 and CYP3A4-mediated warfarin metabolism in hepatic microsomes, resulting in elevated warfarin AUC and Cmax. Additionally, andrographolide and A. paniculata extract exert antiplatelet activity by inhibiting platelet-activating factor (PAF)-induced platelet aggregation (IC50 ~5 µM), providing a pharmacodynamic additive risk on top of the pharmacokinetic enhancement of warfarin levels.

Avoid concurrent use of andrographis with warfarin unless INR can be closely and frequently monitored. If combination is clinically unavoidable, check INR every 3-5 days initially and watch for signs of bleeding (epistaxis, ecchymosis, hematuria, melena). Andrographolide is co-administered with warfarin in some Chinese clinical settings - practitioners worldwide should be aware this combination carries a clinically significant interaction risk requiring active monitoring.

Andrographis paniculata extract and its diterpenoid constituent 14-deoxy-11,12-didehydroandrographolide (AP3) produce dose-dependent vasorelaxation and significant hypotensive effects in vivo. AP3 acts via calcium channel blockade in vascular smooth muscle, exhibiting greater Ca2+ channel blocking capacity than verapamil in some models. Aqueous A. paniculata extract (2 g/kg/day) in high-fat diet mice also decreased myocardial inflammation. In healthy subjects at standard therapeutic doses, A. paniculata has produced transient but meaningful reductions in systolic and diastolic blood pressure. Combined use with antihypertensive drugs carries additive hypotensive pharmacodynamic risk.

Advise patients on antihypertensive therapy to monitor blood pressure when starting andrographis supplementation. Symptomatic hypotension (dizziness, lightheadedness, syncope) may require temporary dose reduction of antihypertensive medications. Exercise particular caution in elderly patients, those on multiple antihypertensives, or volume-depleted individuals. Blood pressure monitoring should be increased in the first 2 weeks after andrographis initiation.

Andrographis paniculata is a well-documented immunostimulant that activates both innate and adaptive immune responses. Andrographolide increases NK cell activity, lymphocyte proliferation, macrophage activation, and cytokine production (TNF-alpha, IL-2, IFN-gamma). This immunostimulatory pharmacodynamic mechanism is directly antagonistic to calcineurin inhibitors (cyclosporine, tacrolimus), antimetabolites (azathioprine, mycophenolate), and corticosteroids used in solid-organ transplant recipients and autoimmune disease patients. By restoring immune competency that these drugs suppress, andrographis may precipitate acute organ rejection or exacerbation of autoimmune conditions.

Andrographis is contraindicated in solid-organ transplant recipients and patients with autoimmune conditions requiring immunosuppression (lupus, rheumatoid arthritis, inflammatory bowel disease). Advise patients to disclose andrographis use during medication reconciliation. Discontinue andrographis at least 2-3 weeks before any planned transplant surgery or when initiating immunosuppressive therapy. Transplant clinicians should specifically ask about herbal medicine use.

Andrographolide and A. paniculata extract exhibit antidiabetic activity via multiple mechanisms: upregulation of GLUT-4 transporter expression, enhancement of pancreatic beta-cell insulin secretion (demonstrated in vitro), inhibition of alpha-glucosidase, and modulation of hepatic gluconeogenic enzymes. Andrographolide also inhibits CYP2C9, CYP3A4, and CYP2C19, the primary enzymes metabolizing most sulfonylureas (tolbutamide, glipizide, glyburide, repaglinide). Pre-clinical systematic review found that co-administration with sulfonylureas generally increased drug exposure (Cmax and AUC) and enhanced glucose-lowering, with repaglinide showing higher Cmax/AUC and augmented hypoglycemia.

Monitor blood glucose closely when andrographis is co-administered with antidiabetic medications, particularly insulin and sulfonylureas, due to additive hypoglycemia risk. Dose adjustments of antidiabetic drugs may be needed. Educate patients on hypoglycemia signs and symptoms (sweating, tremor, confusion). Hold andrographis 24-48 hours before elective fasting procedures or surgeries.

A. paniculata and andrographolide exert dose-dependent and bidirectional effects on CYP1A2. Low-dose A. paniculata extract induces CYP1A2, increasing theophylline clearance and potentially reducing its efficacy. At higher doses, andrographolide inhibits CYP1A2, reducing theophylline clearance and significantly elevating theophylline AUC (P<0.05 in rat studies). Separately, andrographolide was shown to inhibit CYP1A2 in vitro and raised theophylline AUC when co-administered as aminophylline. Theophylline has a narrow therapeutic index (therapeutic range 5-15 mcg/mL), and levels above 20 mcg/mL can cause nausea, arrhythmias, and seizures.

Avoid combining andrographis with theophylline or aminophylline without close therapeutic drug monitoring. If patients on theophylline for asthma or COPD wish to use andrographis, measure theophylline serum levels before and 5-7 days after initiating andrographis and monitor for signs of toxicity (nausea, tachycardia, agitation, tremor). The pharmacokinetic direction of the interaction is dose-dependent and unpredictable in individual patients.

A. paniculata extract and andrographolide alter NSAID pharmacokinetics in animal models by modulating CYP-mediated drug metabolism. Co-administration with aceclofenac and celecoxib significantly changed systemic exposure parameters in Wistar rats. Separately, A. paniculata extract has inherent anti-inflammatory properties via COX-2 inhibition and NF-kappaB suppression, potentially creating synergistic or additive anti-inflammatory effects that may mask pain signals. Both andrographolide and NSAIDs also have antiplatelet properties (andrographolide inhibits PAF-induced platelet aggregation), increasing cumulative bleeding risk when combined.

Monitor patients who use andrographis concurrently with NSAIDs for altered NSAID efficacy and additive bleeding risk. For anti-inflammatory conditions managed with NSAIDs, be aware that andrographis may provide synergistic benefit but also increase GI or systemic bleeding risk. Advise patients to report unusual bleeding, bruising, or black stools. Human pharmacokinetic confirmation of this interaction is still needed.

Andrographolide inhibits platelet aggregation by activating the eNOS-NO-cyclic GMP pathway and inhibiting the PLCgamma2-DAG-PKC and PI3 kinase/Akt cascades, resulting in reduced collagen-induced and ADP-induced platelet aggregation. Combined with antiplatelet drugs, additive inhibition of platelet function increases bleeding risk.

Monitor for excessive bleeding in patients combining Andrographis with antiplatelet therapy. Discontinue Andrographis at least 2 weeks before any surgical procedure. Advise patients to report unusual bruising, prolonged bleeding from cuts, or blood in urine or stool.

A systematic review of herb-drug interactions (Herbmed Pharmacology 2022) found that Andrographis paniculata extract and andrographolide cause complex pharmacokinetic and pharmacodynamic interactions with oral antidiabetics: repaglinide shows higher Cmax and AUC with augmented glucose-lowering effects; metformin shows increased exposure with enhanced glycemic control; glipizide may show synergistic or antagonistic effects depending on preparation type. CYP2C9 inhibitory and induction potential by andrographolide mediates some of these effects.

Monitor blood glucose closely when combining Andrographis with any oral antidiabetic drug; interaction direction and magnitude are preparation-dependent. Risk of hypoglycemia with repaglinide and glimepiride combinations. Dose reduction of antidiabetic agent may be required.

Andrographis paniculata is an immunostimulant that enhances T-cell, NK cell, and macrophage activity. This pharmacodynamic antagonism counteracts the intended immunosuppressive effects of cyclosporine, tacrolimus, and azathioprine used in organ transplantation and autoimmune diseases. Concurrent use risks graft rejection and autoimmune disease flare.

Contraindicated in organ transplant patients receiving immunosuppressive therapy. Avoid use in patients with autoimmune diseases on immunosuppressants. If used, monitor graft function and immunosuppressant trough levels closely.

Multiple animal studies demonstrate that Andrographis paniculata has antifertility effects in both male and female animals: antifertility in male mice, 100% pregnancy inhibition at 2g/kg in female mice, abortion in rabbits, and suppression of human placental chorionic trophoblastic cell growth in vitro. Concurrent use with fertility medications may counteract their intended effects and risk miscarriage.

Andrographis is contraindicated in patients trying to conceive and in pregnancy. Advise patients seeking fertility treatment to discontinue Andrographis completely. Do not use during assisted reproduction cycles.

Systematic review data (Herbmed Pharmacology 2022) indicate that Andrographis paniculata extract and andrographolide significantly alter pharmacokinetic parameters of aminophylline and doxofylline (narrow therapeutic index methylxanthines used in asthma/COPD), primarily via CYP1A2 modulation. Changed Cmax, AUC, and clearance of these drugs increase toxicity or subtherapeutic risk.

Monitor theophylline/aminophylline plasma levels closely in patients using Andrographis concurrently; therapeutic drug monitoring is recommended. Narrow therapeutic window increases risk of toxicity (seizures, cardiac arrhythmia) at elevated drug levels.

Andrographolide and NSAIDs share overlapping anti-inflammatory mechanisms: andrographolide inhibits NF-kB pathway and COX-2 expression, while NSAIDs inhibit COX enzymes directly. A systematic review confirmed pharmacological synergy between andrographolide and meloxicam in animal models of anti-inflammatory activity. Combined use produces enhanced anti-inflammatory and analgesic effect.

Potentially beneficial anti-inflammatory synergy; monitor for GI side effects as both Andrographis and NSAIDs can cause GI irritation. This combination may allow NSAID dose reduction in inflammatory conditions under physician supervision.