Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ADALAT CC vs ACTAHIST
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Nifedipine, a dihydropyridine calcium channel blocker, inhibits calcium ion influx across cardiac and smooth muscle cell membranes, leading to vasodilation and decreased myocardial contractility.
Antihistamine; binds to histamine H1 receptors, blocking the effects of histamine; also exhibits anticholinergic and mild sedative properties.
Hypertension,Chronic stable angina,Vasospastic angina (Prinzmetal's angina)
Symptomatic relief of allergic rhinitis,Urticaria,Off-label: motion sickness,Off-label: insomnia
30 mg orally once daily; may titrate to 60 mg or 90 mg once daily based on response and tolerability.
1.34 mg (one capsule) orally twice daily.
Terminal elimination half-life: 7-10 hours; clinical context: sustained-release formulation provides therapeutic concentrations over 24 hours with once-daily dosing, but half-life does not directly reflect drug effect duration due to slow absorption.
6.9 ± 1.7 hours in adults; prolonged to 12-18 hours in elderly or patients with hepatic impairment, requiring dosing interval adjustment.
Hepatic metabolism via CYP3A4; nifedipine is converted to inactive metabolites.
Hepatic metabolism via CYP450 enzymes (primarily CYP3A4 and CYP2D6); major metabolite is inactive.
Renal: 70-80% as metabolites, fecal: 15-20% as metabolites, biliary: minimal (<5% unchanged).
Primarily renal (approximately 85% as unchanged drug and metabolites) and fecal (15%) via biliary elimination.
92-98% bound primarily to albumin.
92% bound to albumin.
1.2-1.6 L/kg; clinical meaning: indicates extensive tissue distribution, with higher concentrations in organs such as liver and kidney, and lower in brain due to P-glycoprotein efflux.
0.9 ± 0.3 L/kg, indicating extensive extravascular distribution.
65-90% after oral administration; absolute bioavailability of nifedipine in ADALAT CC: approximately 65% due to first-pass metabolism in liver and gut wall.
Oral: 68% ± 12% due to first-pass metabolism.
No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (Cr Cl <30 m L/min), start at 30 mg once daily and titrate cautiously.
No dose adjustment required for mild to moderate renal impairment. Safety not established for severe impairment (GFR <30 m L/min).
For mild to moderate hepatic impairment (Child-Pugh A or B), reduce initial dose to 30 mg once daily; for severe impairment (Child-Pugh C), contraindicated or use with extreme caution.
No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not recommended for severe hepatic impairment (Child-Pugh C).
Safety and efficacy not established; use is not recommended in pediatric patients.
Not indicated for pediatric patients under 12 years of age. Safety and efficacy not established.
Initiate at 30 mg once daily; titrate slowly due to increased risk of hypotension and higher drug exposure. Monitor closely.
No specific dose adjustment recommended; monitor for increased anticholinergic effects and cognitive impairment.
No FDA black box warning.
None.
Beta-blocker withdrawal: taper if discontinuing; exacerbation of angina,Heart failure: use caution in patients with severe left ventricular dysfunction,Hepatic impairment: reduce dose,Peripheral edema: may occur; differentiate from worsening heart failure,Monitor blood pressure during initiation and titration
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.
Hypersensitivity to nifedipine or any component,Cardiogenic shock,Concurrent use with strong CYP3A4 inducers (e.g., rifampin)
Hypersensitivity to any component. Newborns or premature infants. Breastfeeding (contraindicated due to risk of adverse effects in infants). Concomitant use with MAOIs.
Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 metabolism, raising nifedipine levels and risk of toxicity. High-fat meals may increase absorption; take consistently with respect to meals. Avoid alcohol as it may exacerbate hypotension.
Avoid high-tyramine foods (aged cheese, cured meats, fermented products) if taking MAOIs. Grapefruit juice may increase phenylephrine absorption; limit intake.
Adalat CC (nifedipine) is an extended-release formulation of nifedipine, a dihydropyridine calcium channel blocker. In animal studies, nifedipine has been associated with embryotoxicity, fetotoxicity, and teratogenicity (e.g., digital anomalies, cleft palate) at doses several times the maximum recommended human dose. In humans, data are limited but there is no clear evidence of a significant increase in major congenital malformations. First trimester exposure is not strongly associated with major defects; however, some studies suggest a possible small increase in oral clefts. Second and third trimester use may cause maternal hypotension and subsequent fetal distress (e.g., reduced uteroplacental perfusion). Use near term may theoretically inhibit labor, but nifedipine is used as a tocolytic for preterm labor. Overall, the risk is considered low; however, fetal monitoring is recommended if used in pregnancy. FDA Pregnancy Category C (prior to 2015 categorization).
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.
Nifedipine is excreted into human breast milk in small amounts. The milk-to-plasma (M/P) ratio is approximately 0.56 to 1.0 based on limited data. The estimated daily infant dose via milk is less than 5% of the maternal weight-adjusted dose, which is considered clinically insignificant. No adverse effects have been reported in breastfed infants. However, caution is advised, especially with high maternal doses or prolonged use. The American Academy of Pediatrics considers nifedipine compatible with breastfeeding.
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.
Pregnancy may alter the pharmacokinetics of nifedipine due to increased plasma volume and altered hepatic metabolism. However, specific dosing adjustments for Adalat CC in pregnancy are not well established. In clinical practice, dosing for hypertension in pregnancy (e.g., preeclampsia) often uses immediate-release nifedipine, not extended-release. For Adalat CC, the same dosing as in non-pregnant adults (30-90 mg once daily) is typically used, but titration should be cautious to avoid maternal hypotension. No formal dose adjustment is recommended, but careful monitoring and individualized titration are advised.
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.
Adalat CC (nifedipine extended-release) is a dihydropyridine calcium channel blocker used primarily for hypertension. Avoid in patients with unstable angina or within 4 weeks of myocardial infarction due to reflex tachycardia risk. May cause peripheral edema, especially in higher doses; consider adding an ACE inhibitor if edema is problematic. CYP3A4 inhibitors (e.g., grapefruit juice, macrolides, azole antifungals) significantly increase nifedipine levels; avoid coadministration. Tablet shell may appear intact in stool; this is normal.
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.
Swallow the tablet whole; do not crush or chew.,Do not consume grapefruit or grapefruit juice while taking this medication.,May cause dizziness or lightheadedness; avoid driving if affected.,Notify your doctor if you experience rapid heartbeat, swelling in the ankles or feet, or prolonged erections.,Take exactly as prescribed; do not skip doses or stop abruptly without consulting your doctor.
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.
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 ADALAT CC vs ACTAHIST, answered by our medical review team.
ADALAT CC is a Calcium Channel Blocker that works by Nifedipine, a dihydropyridine calcium channel blocker, inhibits calcium ion influx across cardiac and smooth muscle cell membranes, leading to vasodilation and decreased myocardial contractility.. 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ADALAT CC and ACTAHIST 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 ADALAT CC is: 30 mg orally once daily; may titrate to 60 mg or 90 mg once daily based on response and tolerability.. The standard adult dose of ACTAHIST is: 1.34 mg (one capsule) orally twice daily.. 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 ADALAT CC and ACTAHIST 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. ADALAT CC is classified as Category C. Adalat CC (nifedipine) is an extended-release formulation of nifedipine, a dihydropyridine calcium channel blocker. In animal studies, nifedipine has been associated with embryotox. 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. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.