Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CAFERGOT vs ACYCLOVIR IN SODIUM CHLORIDE 0.9% PRESERVATIVE FREE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Ergotamine is a serotonin (5-HT1B/1D) receptor agonist that causes vasoconstriction of cranial blood vessels and inhibits neurogenic inflammation. Caffeine is a methylxanthine that enhances ergotamine absorption and may contribute to vasoconstriction.
Acyclovir is a synthetic purine nucleoside analog with inhibitory activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), and varicella-zoster virus (VZV). After intracellular conversion to acyclovir triphosphate, it inhibits viral DNA polymerase, leading to chain termination and viral DNA replication inhibition.
Acute treatment of migraine headaches with or without aura,Acute treatment of cluster headache episodes
Treatment of herpes simplex virus (HSV) infections (genital herpes, herpes labialis, herpes simplex encephalitis),Treatment of varicella-zoster virus (VZV) infections (chickenpox, herpes zoster),Neonatal herpes simplex virus infection,Off-label: Prevention of HSV reactivation in immunocompromised patients, treatment of eczema herpeticum
1 to 2 tablets (each containing ergotamine tartrate 1 mg and caffeine 100 mg) orally at onset of migraine, then 1 tablet every 30 minutes as needed, maximum 6 tablets per attack or 10 tablets per week. Alternatively, 1 rectal suppository (ergotamine tartrate 2 mg and caffeine 100 mg) at onset, repeat once after 1 hour if needed, maximum 2 suppositories per attack or 5 per week.
5 mg/kg IV every 8 hours (or 10 mg/kg IV every 8 hours for varicella-zoster or herpes simplex encephalitis) infused over 1 hour.
2.5-3.9 hours (ergotamine); clinical context: t1/2 may be prolonged in hepatic impairment.
Terminal elimination half-life in adults with normal renal function is 2.5-3.3 hours. In anuric patients, half-life extends to approximately 19.5 hours, necessitating dosage adjustment in renal impairment.
Primarily hepatic via CYP3A4; ergotamine is extensively metabolized, and caffeine is metabolized via CYP1A2.
Acyclovir is partially metabolized by aldehyde oxidase and alcohol dehydrogenase to 9-carboxymethoxymethylguanine and other minor metabolites. The majority (62-90%) is excreted unchanged in urine via glomerular filtration and tubular secretion.
Primarily hepatic metabolism and biliary excretion; less than 5% excreted unchanged in urine. Fecal elimination accounts for most of the administered dose.
Primarily renal excretion via glomerular filtration and tubular secretion; approximately 62-91% of an administered dose is recovered unchanged in urine. Fecal excretion is minimal (<2%).
98-99% bound to plasma proteins, primarily albumin.
9-33% bound to plasma proteins; binding is concentration-independent and predominantly to albumin.
1.1-2.0 L/kg; clinical meaning: extensive tissue distribution, particularly into liver and spleen.
Approximately 0.7 L/kg, indicating distribution into total body water. Penetrates well into tissues, including cerebrospinal fluid (CSF concentrations ~50% of plasma).
Oral: <5% due to extensive first-pass metabolism; Sublingual: approximately 15-20%; Rectal: approximately 20-30%.
Intravenous administration yields 100% bioavailability. Oral bioavailability is 15-30% (not applicable to IV formulation).
Contraindicated in severe renal impairment. In moderate renal impairment (e GFR 30-59 m L/min/1.73 m²): use with caution; dose reduction not specifically defined but monitor for adverse effects. Mild impairment (e GFR ≥60 m L/min/1.73 m²): no adjustment needed.
Cr Cl >50 m L/min: no adjustment; Cr Cl 25-50 m L/min: 5-10 mg/kg every 12 hours; Cr Cl 10-25 m L/min: 5-10 mg/kg every 24 hours; Cr Cl <10 m L/min: 2.5-5 mg/kg every 24 hours; hemodialysis: give dose after dialysis.
Contraindicated in Child-Pugh Class C. Child-Pugh Class A: no adjustment; Class B: use with caution, reduce dose by 50% and monitor. No specific dose recommendations from manufacturer; clinical judgment advised.
No dose adjustment required for hepatic impairment; acyclovir is minimally metabolized by the liver.
Not recommended for use in pediatric patients due to risk of ergotism and lack of safety data. No established weight-based dosing.
Neonates (0-3 months): 10 mg/kg IV every 8 hours for HSV; Infants and children (3 months-12 years): 10 mg/kg IV every 8 hours for HSV, 20 mg/kg IV every 8 hours for VZV; maximum dose 500 mg/m² per dose.
Use with caution due to increased risk of ergotism, renal/hepatic impairment, and drug interactions. Lower initial dose (e.g., 1 tablet) and careful monitoring. Avoid in patients over 65 with significant vascular disease.
Elderly patients may have reduced renal function; adjust dose based on Cr Cl and monitor for neurotoxicity (e.g., confusion, hallucinations).
Serious and/or life-threatening peripheral ischemia has been associated with coadministration of ergotamine with potent CYP3A4 inhibitors (including protease inhibitors, macrolide antibiotics, and azole antifungals).
None.
Risk of ergotism (ischemia, gangrene) with prolonged use or overdosage,May cause vasospastic reactions, including coronary artery vasospasm and myocardial infarction,Rebound headache (medication overuse headache) with frequent use,Caffeine withdrawal may exacerbate headaches,Avoid concurrent use with potent CYP3A4 inhibitors
Renal impairment: Dose adjustment required; monitor renal function.,Neurotoxicity: May cause agitation, hallucinations, confusion, seizures (especially in elderly or renally impaired).,Crystalluria: Risk increased with rapid infusion or dehydration; ensure adequate hydration.,Hemolytic uremic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP): Rare but serious, reported in immunocompromised patients.,Pregnancy: Use only if clearly needed (Category B).
Peripheral vascular disease,Coronary artery disease,Hypertension (uncontrolled),Sepsis,Severe hepatic or renal impairment,Pregnancy (Category X),Breastfeeding,Concurrent use of potent CYP3A4 inhibitors
Hypersensitivity to acyclovir, valacyclovir, or any component of the formulation.,Neonates: Use of bacteriostatic water-containing preparations (e.g., benzyl alcohol) is contraindicated.
Avoid excessive caffeine intake (e.g., coffee, tea, cola, energy drinks) as Cafergot contains caffeine and may cause additive stimulation or toxicity. Limit caffeine to no more than 200 mg per day during treatment.
No specific food interactions. Adequate fluid intake is recommended to prevent renal toxicity. Avoid concurrent use of nephrotoxic substances (e.g., certain NSAIDs, aminoglycosides) without medical supervision.
FDA Category X. First trimester: ergotamine is a potent vasoconstrictor and uterine stimulant, associated with increased risk of spontaneous abortion, congenital anomalies (including micrognathia, microphthalmia, cleft palate, and limb defects). Second and third trimesters: continued risk of uteroplacental insufficiency, intrauterine growth restriction, preterm labor, and fetal distress due to vasoconstriction and increased uterine tone.
FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Limited human data: no increased risk of major birth defects or miscarriage. Risk cannot be ruled out; use only if clearly needed.
Contraindicated during breastfeeding. Ergotamine reduces prolactin secretion and may suppress lactation. It is excreted into breast milk; M/P ratio not established. Reported infant adverse effects include vomiting, diarrhea, and seizures. Risk of vasospasm and ergotism in the infant.
Acyclovir excreted in breast milk at low levels; M/P ratio unknown. Typical infant dose ~0.6 mg/kg/day (2-3% of maternal IV dose). No adverse effects reported in breastfeeding infants. Compatible with breastfeeding; caution with high maternal doses.
Contraindicated in pregnancy; no dosing adjustments recommended. Use is not safe; alternative therapy should be sought.
Increased renal clearance and volume of distribution in pregnancy may reduce acyclovir exposure. No dose adjustment routinely recommended; however, higher doses or more frequent dosing may be considered for severe infections. Monitor therapeutic response.
Cafergot is ergotamine-caffeine combination for acute migraine. Avoid in pregnancy, uncontrolled hypertension, CAD, and peripheral vascular disease. Maximum dose: 6 tablets per attack or 10 tablets per week. Use at first sign of migraine. Not for prophylaxis. Can cause ergotism with prolonged use. Monitor for signs of ischemia.
Acyclovir in sodium chloride 0.9% preservative-free is for IV administration only; do not administer IM or SC. Infuse over at least 1 hour to prevent renal tubular damage. Monitor renal function and adjust dose in renal impairment (Cr Cl <50 m L/min). Ensure adequate hydration (e.g., 500 m L IV fluids per gram acyclovir) to reduce risk of crystalluria. In obese patients, use ideal body weight for dosing. Phlebitis at infusion site is common; rotate sites.
Take at the first sign of migraine headache for best effect.,Do not take more than 6 tablets per attack or 10 tablets per week.,Avoid use if you are pregnant, breastfeeding, or have high blood pressure, heart disease, or circulation problems.,Seek emergency care if you experience severe stomach pain, chest pain, numbness, tingling, or muscle cramps.,Do not take with other ergotamine drugs or strong CYP3A4 inhibitors (e.g., azole antifungals, macrolide antibiotics).,Store at room temperature, away from heat and moisture.
This medication is given intravenously (into a vein) to treat viral infections.,Drink plenty of fluids before and during treatment to prevent kidney problems.,Report any pain, redness, or swelling at the injection site, or any lower back pain.,Tell your healthcare provider if you have kidney disease or are taking other medications that can affect the kidneys.,This drug does not cure herpes infections but helps reduce symptoms and recurrence.
No interactions on record
"Teriflunomide, the active metabolite of leflunomide, inhibits dihydroorotate dehydrogenase (DHODH), a key enzyme in de novo pyrimidine synthesis, exerting immunomodulatory effects. Acyclovir, an antiviral nucleoside analog, may inhibit organic anion transporter 3 (OAT3)-mediated renal tubular secretion of teriflunomide, leading to increased systemic exposure. Elevated teriflunomide concentrations can potentiate hepatotoxicity, myelosuppression, and immunosuppression, increasing the risk of infections and other adverse effects."
"The serum concentration of Acyclovir can be increased when it is combined with Tizanidine."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CAFERGOT vs ACYCLOVIR IN SODIUM CHLORIDE 0.9% PRESERVATIVE FREE, answered by our medical review team.
CAFERGOT is a Antimigraine Agent (Ergot Alkaloid) that works by Ergotamine is a serotonin (5-HT1B/1D) receptor agonist that causes vasoconstriction of cranial blood vessels and inhibits neurogenic inflammation. Caffeine is a methylxanthine that enhances ergotamine absorption and may contribute to vasoconstriction.. ACYCLOVIR IN SODIUM CHLORIDE 0.9% PRESERVATIVE FREE is a Electrolyte that works by Acyclovir is a synthetic purine nucleoside analog with inhibitory activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), and varicella-zoster virus (VZV). After intracellular conversion to acyclovir triphosphate, it inhibits viral DNA polymerase, leading to chain termination and viral DNA replication inhibition.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CAFERGOT and ACYCLOVIR IN SODIUM CHLORIDE 0.9% PRESERVATIVE FREE 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 CAFERGOT is: 1 to 2 tablets (each containing ergotamine tartrate 1 mg and caffeine 100 mg) orally at onset of migraine, then 1 tablet every 30 minutes as needed, maximum 6 tablets per attack or 10 tablets per week. Alternatively, 1 rectal suppository (ergotamine tartrate 2 mg and caffeine 100 mg) at onset, repeat once after 1 hour if needed, maximum 2 suppositories per attack or 5 per week.. The standard adult dose of ACYCLOVIR IN SODIUM CHLORIDE 0.9% PRESERVATIVE FREE is: 5 mg/kg IV every 8 hours (or 10 mg/kg IV every 8 hours for varicella-zoster or herpes simplex encephalitis) infused over 1 hour.. 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 CAFERGOT and ACYCLOVIR IN SODIUM CHLORIDE 0.9% PRESERVATIVE FREE 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. CAFERGOT is classified as Category C. FDA Category X. First trimester: ergotamine is a potent vasoconstrictor and uterine stimulant, associated with increased risk of spontaneous abortion, congenital anomalies (includi. ACYCLOVIR IN SODIUM CHLORIDE 0.9% PRESERVATIVE FREE is classified as Category A/B. FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Limited human data: no increased risk of major birth defects or miscarriage. Risk cannot be ruled out; us. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.