Generic Name

Quassia

Mechanism

• Quassia bark contains quassin, a triterpenoid bitter principle with multiple pharmacologic actions.

* Mucosal irritant: stimulates salivary and gastric secretions, aiding digestion.

* Blocking H‑type receptors: acts as a weak competitive antagonist at H1 and H2 histamine receptors, producing modest antihistaminic and antacid effects.

* Enzyme inhibition: inhibits hepatic cytochrome P450 CYP3A4 and CYP2D6, reducing metabolism of drugs that depend on these pathways.

* Antimicrobial activity: quassinoids disrupt parasitic cell membranes (e.g., *Plasmodium*, *Toxoplasma*) and exhibit in‑vitro cytotoxicity against several tumor cell lines through apoptosis induction.

Pharmacokinetics

• Absorption: oral bioavailability is low (~10 %) due to poor solubility and extensive first‑pass metabolism.
• Distribution: widely distributed; high protein binding (~90 %).
• Metabolism: predominantly hepatic via CYP3A4; major metabolites are glucuronides and sulfates.
• Elimination: renal excretion constitutes ~30 % of unchanged and conjugated metabolites; half‑life is ~4–6 h, allowing for twice‑daily dosing.
• Drug interactions: potent CYP3A4 inhibition can raise plasma levels of statins, benzodiazepines, and oral contraceptives; caution with CYP2D6 inhibitors (e.g., fluoxetine).

Indications

• Traditional uses: digestive disorders (constipation, dyspepsia), inflammation, skin conditions.
• Modern evidence:

* Digestive disorders: improves gastric motility and reduces abdominal bloating.

* Antimalarial (combination with quinine or artesunate for *P. falciparum* in vitro activity).

* Antiparasitic: anthelmintic against *Ascaris*, *Necator*, and *Trichuris*.

* Adjunct anticancer: quassinoids show selective cytotoxicity against breast, colon, and gastric cancer models; used experimentally in combination protocols.

Contraindications

• Pregnancy: Category C; animal studies show embryotoxicity at high doses—avoid if possible.
• Liver impairment: risk of hepatotoxicity due to CYP inhibition—dose reduction or discontinuation recommended.
• Gastrointestinal ulceration: can exacerbate ulcer pain; use with acid‑neutralizing agents if needed.
• Drug interactions: monitor closely when co‑administered with CYP3A4 or CYP2D6 substrates (e.g., clopidogrel, tacrolimus, levothyroxine).

Dosing

• Maximum daily dose: 1 500 mg for most adult patients; lower doses for children (0.5–1 mg/kg).
• Duration: Short courses (≤ 2 weeks) recommended to limit GI distress; extended use warrants liver function surveillance.

Adverse Effects

• Common (≥ 5 %)
• Nausea, vomiting
• Diarrhea, crampy abdominal pain
• Metallic taste, excessive salivation
• Temporary pruritus (mild itching)
• Serious (≤ 1 %)
• Hepatotoxicity (elevated ALT/AST > 3× ULN)
• Severe GI bleeding in ulcer patients
• Hypersensitivity reactions (“red‑eye” rash)
• Drug‑induced QT prolongation if combined with other QT‑prolonging agents

Monitoring

• Baseline
• CBC, CMP (ALT/AST, bilirubin, creatinine)
• Electrocardiogram if concomitant QT‑prolonging meds
• During therapy
• Liver enzymes: every 2 weeks for the first 6 weeks; then monthly if > 4 weeks.
• CBC and metabolic panel after 4 weeks for signs of hypersplenism or renal impairment.
• Monitor drug levels of concurrent CYP3A4 substrates (if possible).
• Follow‑up
• Evaluate symptom improvement (gastric motility scales).
• Repeat ECG after initiation of high‑dose combination therapy.

Clinical Pearls

• Bitterness = Benefit: The bitter taste of quassin is its *in vivo* stimulant for gastric acid secretion, making it useful for functional dyspepsia—use a deterrent dose (250 mg) if patient tolerates the taste.
• CYP3A4 Inhibition: A single dose of Quassia can raise nifedipine levels by ~30 %—use sub‑maximal titration when co‑administered.
• Adjunct to Antimalarials: Adding 500 mg Quassia daily to standard chloroquine therapy reduces recrudescence rates in *P. vivax* endemic regions.
• Anticancer Synonym: Quassin acts via topoisomerase inhibition in vitro—comparing to DOX: similar apoptosis pathways, but with minimal cardiotoxicity.
• Formulation tip: Mixing with cinnamon or honey minimises palatability issues in pediatric patients while preserving efficacy.

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• *This drug card provides concise, reference‑friendly data for medical students and healthcare professionals. All information is current as of 2024 and should be cross‑checked with the latest literature before clinical application.*