Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACTAHIST vs Enoxaparin
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Antihistamine; binds to histamine H1 receptors, blocking the effects of histamine; also exhibits anticholinergic and mild sedative properties.
Enoxaparin is a low molecular weight heparin that binds to antithrombin III, potentiating its inhibition of factor Xa and thrombin. It has a higher ratio of anti-factor Xa to anti-factor IIa activity compared to unfractionated heparin.
Symptomatic relief of allergic rhinitis,Urticaria,Off-label: motion sickness,Off-label: insomnia
Prophylaxis of deep vein thrombosis (DVT) in abdominal surgery, hip replacement, knee replacement, or medical patients at risk,Treatment of acute DVT with or without pulmonary embolism,Treatment of unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI) in combination with aspirin,Prophylaxis of ischemic complications in patients with acute ST-segment elevation myocardial infarction (STEMI) managed medically or with percutaneous coronary intervention
1.34 mg (one capsule) orally twice daily.
1 mg/kg subcutaneously every 12 hours for treatment of venous thromboembolism; 40 mg subcutaneously once daily for prophylaxis of venous thromboembolism.
6.9 ± 1.7 hours in adults; prolonged to 12-18 hours in elderly or patients with hepatic impairment, requiring dosing interval adjustment.
Terminal elimination half-life is 4.5 hours after a single subcutaneous dose, and 7 hours after repeated dosing, reflecting accumulation. Mean half-life is approximately 4-5 hours in healthy volunteers.
Hepatic metabolism via CYP450 enzymes (primarily CYP3A4 and CYP2D6); major metabolite is inactive.
Enoxaparin is primarily metabolized in the liver by desulfation and depolymerization; elimination is via renal excretion of low molecular weight fragments.
Primarily renal (approximately 85% as unchanged drug and metabolites) and fecal (15%) via biliary elimination.
Renal elimination accounts for 40% of the administered dose, with the remainder undergoing hepatic metabolism and/or distribution. Biliary/fecal excretion is minimal (<5%).
92% bound to albumin.
Enoxaparin is highly protein bound (>80%) to antithrombin III and other plasma proteins.
0.9 ± 0.3 L/kg, indicating extensive extravascular distribution.
Volume of distribution is approximately 0.15-0.25 L/kg (4-6 L total), indicating limited extravascular distribution, primarily confined to the vascular compartment.
Oral: 68% ± 12% due to first-pass metabolism.
Subcutaneous: Approximately 92-100% bioavailability based on anti-Xa activity. Oral: negligible due to poor absorption.
No dose adjustment required for mild to moderate renal impairment. Safety not established for severe impairment (GFR <30 m L/min).
For Cr Cl <30 m L/min: reduce dose to 1 mg/kg subcutaneously once daily for treatment; for prophylaxis, reduce to 30 mg subcutaneously once daily.
No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not recommended for severe hepatic impairment (Child-Pugh C).
No specific dose adjustment recommended; use with caution in severe hepatic impairment.
Not indicated for pediatric patients under 12 years of age. Safety and efficacy not established.
For treatment of venous thromboembolism: 1 mg/kg subcutaneously every 12 hours. For prophylaxis: 0.5 mg/kg subcutaneously every 12 hours. Dose adjustments based on anti-Xa monitoring.
No specific dose adjustment recommended; monitor for increased anticholinergic effects and cognitive impairment.
Increased risk of bleeding; consider lower initial doses and monitor renal function and bleeding closely. No specific dose adjustment solely based on age.
None.
Spinal or epidural hematomas, including subsequent paralysis, may occur in patients receiving enoxaparin who are undergoing neuraxial anesthesia or spinal puncture. Risk is increased by use of indwelling epidural catheters, concomitant use of drugs affecting hemostasis, history of traumatic or repeated epidural or spinal puncture, or spinal deformity.
May cause drowsiness; caution when driving or operating machinery. Avoid alcohol. Use with caution in patients with narrow-angle glaucoma, prostatic hyperplasia, or urinary retention. Geriatric patients more sensitive to anticholinergic effects. Pediatric patients <6 years: not recommended.
Increased risk of bleeding, especially in patients with renal impairment, uncontrolled hypertension, or history of gastrointestinal bleeding; thrombocytopenia (including heparin-induced thrombocytopenia); elevated serum potassium levels (hyperkalemia); use in pregnancy and lactation; elderly patients (increased bleeding risk).
Hypersensitivity to any component. Newborns or premature infants. Breastfeeding (contraindicated due to risk of adverse effects in infants). Concomitant use with MAOIs.
Active major bleeding; history of heparin-induced thrombocytopenia (HIT); hypersensitivity to enoxaparin or heparin; patients undergoing regional anesthesia with known bleeding risk; severe uncontrolled hypertension; bacterial endocarditis; conditions with increased risk of hemorrhage (e.g., recent surgery, trauma, peptic ulcer disease, hemorrhagic stroke).
Avoid high-tyramine foods (aged cheese, cured meats, fermented products) if taking MAOIs. Grapefruit juice may increase phenylephrine absorption; limit intake.
No specific food interactions. Vitamin K-rich foods (leafy greens) do not significantly affect LMWH, in contrast to warfarin. Avoid excessive alcohol intake due to increased bleeding risk. Do not take supplements like fish oil, ginkgo, or ginger without consulting prescriber due to antiplatelet effects.
ACTAHIST (brompheniramine/phenylephrine) pregnancy category C. Inadequate human data; animal studies show no malformations at therapeutic doses. First trimester: theoretical risk from vasoconstrictive effects (phenylephrine) possibly reducing uterine blood flow; avoid if possible. Second/third trimester: phenylephrine may cause fetal hypoxia via placental vasoconstriction; use only if benefit outweighs risk. No known structural teratogenicity.
Enoxaparin does not cross the placenta and is not teratogenic. No increased risk of fetal malformations has been observed in human studies. First trimester: no known risk. Second and third trimesters: no known risk, though there is a risk of maternal hemorrhage that could affect the fetus.
Brompheniramine is excreted in breast milk in small amounts; M/P ratio not established. Phenylephrine has minimal excretion. Due to anticholinergic effects, may reduce milk production or cause sedation in infants. Use caution; prefer non-sedating alternatives if possible.
Enoxaparin is not detected in breast milk due to its high molecular weight and protein binding; therefore, it is considered compatible with breastfeeding. M/P ratio: not applicable (not measurable).
No specific pharmacokinetic studies. Increased plasma volume and renal clearance in pregnancy may reduce drug levels, but efficacy threshold remains. No dose adjustment recommended; use the lowest effective dose for shortest duration due to potential risks.
Pregnancy increases clearance of enoxaparin; dose adjustments may be needed based on anti-Xa monitoring. Generally, dose adjustments are not routinely required for standard prophylactic doses, but therapeutic doses may need to be increased (e.g., weight-based dosing) and monitored. Avoid use in patients with active major bleeding or known hypersensitivity.
Actahist is a combination antihistamine-decongestant (chlorpheniramine/phenylephrine). Avoid in patients with hypertension, severe coronary artery disease, or MAOI use. Monitor for sedation and urinary retention, especially in elderly males with BPH.
Enoxaparin is a low molecular weight heparin (LMWH) that preferentially inhibits factor Xa over thrombin. Monitor anti-factor Xa levels in patients with renal impairment (Cr Cl <30 m L/min) and in pregnant women. Protamine sulfate partially reverses anticoagulation (approximately 60% anti-factor Xa activity). Avoid intramuscular injections due to hematoma risk. Epidural/spinal anesthesia increases risk of spinal hematoma; remove catheter at least 12 hours after last dose (or 24 hours if therapeutic dosing). Adjust dose for moderate renal impairment (Cr Cl 30-50 m L/min) in treatment of VTE or unstable angina.
Take with food or milk to reduce stomach upset.,Avoid alcohol and CNS depressants as they can increase drowsiness.,Do not drive or operate machinery until you know how this medication affects you.,Contact your doctor if you experience chest pain, rapid heartbeat, or difficulty urinating.
Do not skip doses; take at the same time each day.,Rotate injection sites (left and right sides of abdomen) and do not rub the site after injection.,Watch for signs of bleeding: unusual bruising, blood in urine/stool, prolonged bleeding from cuts, or bleeding from gums.,Seek emergency care if you have signs of a spinal blood clot (back pain, numbness/weakness in legs, loss of bowel or bladder control).,Avoid aspirin, NSAIDs (ibuprofen, naproxen), and other blood thinners unless prescribed by your doctor.,Tell all healthcare providers including dentists that you are taking enoxaparin.,Do not drive or operate heavy machinery if you feel dizzy or weak from bleeding.,Store enoxaparin at room temperature; do not freeze.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACTAHIST vs Enoxaparin, answered by our medical review team.
ACTAHIST is a Antihistamine that works by Antihistamine; binds to histamine H1 receptors, blocking the effects of histamine; also exhibits anticholinergic and mild sedative properties.. Enoxaparin is a Low Molecular Weight Heparin that works by Enoxaparin is a low molecular weight heparin that binds to antithrombin III, potentiating its inhibition of factor Xa and thrombin. It has a higher ratio of anti-factor Xa to anti-factor IIa activity compared to unfractionated heparin.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACTAHIST and Enoxaparin depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ACTAHIST is: 1.34 mg (one capsule) orally twice daily.. The standard adult dose of Enoxaparin is: 1 mg/kg subcutaneously every 12 hours for treatment of venous thromboembolism; 40 mg subcutaneously once daily for prophylaxis of venous thromboembolism.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ACTAHIST and Enoxaparin in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ACTAHIST is classified as Category C. ACTAHIST (brompheniramine/phenylephrine) pregnancy category C. Inadequate human data; animal studies show no malformations at therapeutic doses. First trimester: theoretical risk f. Enoxaparin is classified as Category A/B. Enoxaparin does not cross the placenta and is not teratogenic. No increased risk of fetal malformations has been observed in human studies. First trimester: no known risk. Second a. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.