Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACHROMYCIN vs ACTICLATE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Tetracycline antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-t RNA from binding to the A site.
Inhibits P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), thereby increasing intestinal absorption and decreasing clearance of substrates; also inhibits CYP3A4 isoenzymes, reducing metabolism of CYP3A4 substrates.
Infections caused by susceptible strains of bacteria (e.g., Mycoplasma pneumoniae, Chlamydia trachomatis, Rickettsia species),Acne vulgaris,Periodontitis (as adjunctive therapy),Off-label: Chronic obstructive pulmonary disease exacerbations, malaria prophylaxis
Adjuvant therapy to antibiotics for treatment of refractory infections caused by multidrug-resistant organisms,Off-label: Treatment of hyperuricemia in gout (as a urate-lowering agent when combined with allopurinol),Investigationally: Reversal of P-gp-mediated resistance in certain malignancies
250-500 mg orally every 6 hours or 500 mg intravenously every 12 hours.
100 mg orally twice daily (12 hours apart) on an empty stomach (1 hour before or 2 hours after meals). Avoid milk, antacids, iron, calcium, magnesium, and zinc within 2 hours of administration.
6-12 hours; prolonged to 48-72 hours in severe renal impairment
Terminal elimination half-life is approximately 18-22 hours in patients with normal renal function; prolonged to 30-50 hours in moderate renal impairment (Cr Cl 30-50 m L/min).
Primarily renally excreted unchanged; minimal hepatic metabolism.
Primarily hepatic via CYP3A4 and CYP2D6; also undergoes glucuronidation and renal excretion.
Renal (60-80% unchanged via glomerular filtration); biliary/fecal (10-20%)
Renal excretion of unchanged drug accounts for approximately 60% of the dose; fecal elimination via biliary secretion contributes about 30%; minor metabolism (<10%) produces inactive metabolites.
50-60% bound to serum proteins
Approximately 75-80% bound primarily to serum albumin and to a lesser extent to alpha-1-acid glycoprotein.
1.5-2.0 L/kg; indicates extensive tissue penetration
Volume of distribution is 1.5-2.5 L/kg, indicating extensive tissue distribution; penetrates well into lung, skin, and soft tissues.
Oral: 75-80%; Topical: minimal systemic absorption
Oral bioavailability is approximately 95% with minimal first-pass metabolism; food reduces absorption by 20-30%.
GFR 50-80 m L/min: no adjustment; GFR 10-50 m L/min: administer every 12-24 hours; GFR <10 m L/min: administer every 24 hours or avoid.
e GFR 30-60 m L/min/1.73m²: No adjustment needed; e GFR <30 m L/min: Avoid use (contraindicated due to tetracycline accumulation).
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
Child-Pugh Class A or B: No adjustment; Child-Pugh Class C: Avoid use (insufficient data, potential hepatotoxicity).
25-50 mg/kg/day orally divided every 6 hours; maximum 2 g/day.
Weight ≥45 kg and age ≥12 years: 100 mg every 12 hours for 10 days. Weight <45 kg or age <12 years: Not recommended (risk of permanent tooth discoloration and bone growth inhibition).
Initiate at lower end of dosing range due to age-related renal function decline; monitor renal function.
Use with caution due to increased risk of intracranial hypertension and photosensitivity. Consider renal function; no specific dose adjustment beyond renal dosing.
No FDA boxed warning
None.
Photosensitivity reactions,Esophageal ulceration if taken with insufficient fluids,Pseudotumor cerebri in adults,Pancreatitis,Hepatotoxicity,Renal impairment (accumulation may worsen renal function),Superinfection with resistant organisms
May cause significant drug interactions due to inhibition of P-gp, BCRP, and CYP3A4; monitor for increased toxicity of coadministered drugs (e.g., digoxin, methotrexate, anticancer agents). Use with caution in patients with hepatic impairment.
Hypersensitivity to tetracyclines,Pregnancy (second and third trimesters) due to fetal harm,Children under 8 years due to permanent tooth discoloration and enamel hypoplasia,Severe hepatic or renal impairment
Hypersensitivity to active ingredient; concurrent use with narrow therapeutic index drugs that are P-gp or CYP3A4 substrates (e.g., digoxin, colchicine, cyclosporine) unless benefit outweighs risk.
Avoid dairy products (milk, cheese, yogurt) within 2-3 hours of taking Achromycin, as calcium binds tetracycline and reduces absorption. Also avoid iron-fortified foods, calcium-fortified juices, and high-calcium meals. Take on an empty stomach with a full glass of water; food, especially dairy, decreases absorption by up to 50%.
Dairy products (milk, yogurt, cheese), calcium-fortified foods, and high-calcium meals reduce doxycycline absorption. Take doxycycline at least 1-2 hours before or after consuming these foods. Avoid concurrent use with antacids, iron supplements, bismuth subsalicylate, and magnesium-containing laxatives. Alcohol is not known to interact but may increase gastrointestinal irritation.
ACHROMYCIN (tetracycline) is classified as FDA Pregnancy Category D. First trimester: Associated with minor malformations, but risk is low. Second and third trimesters: Exposure can cause permanent discoloration of deciduous teeth (yellow-gray-brown) due to deposition during calcification, and reversible inhibition of bone growth. Avoid use after the fourth month of pregnancy. Risk of maternal hepatotoxicity if used intravenously in pregnancy.
FDA Pregnancy Category D. Tetracyclines, including doxycycline (active ingredient in ACTICLATE), can cause fetal harm when administered to a pregnant woman. Use during tooth development (second and third trimesters) may cause permanent discoloration of teeth (yellow-gray-brown) and enamel hypoplasia. Use during skeletal development may cause reversible inhibition of bone growth. Avoid during pregnancy; alternative therapy should be considered.
Tetracycline is excreted into breast milk in low concentrations. Theoretical risk of dental discoloration and bone growth suppression in nursing infants, but levels are usually below therapeutic. M/P ratio is approximately 0.5-0.8. Use with caution, especially in infants with prolonged exposure. American Academy of Pediatrics considers tetracyclines compatible with breastfeeding.
Doxycycline is excreted in human milk at low concentrations. The milk-to-plasma ratio is approximately 0.6-0.9. Theoretical risk of dental discoloration and bone growth inhibition in nursing infants exists due to cumulative effects, although absorption by the infant is limited. Caution is advised; consider temporary discontinuation of breastfeeding during treatment or use alternative agent.
No dosage adjustment is recommended for pregnancy; however, use is contraindicated after the first trimester due to risks to the fetus. If essential, use the lowest effective dose for the shortest duration. Intravenous doses should be cautious due to risk of hepatotoxicity; reduce dose in renal impairment.
Doxycycline is contraindicated in pregnancy; no dose adjustment is applicable. If inadvertent exposure occurs in first trimester, no dose adjustment needed, but drug should be discontinued. No pharmacokinetic data suggesting need for dose adjustment if used for life-threatening conditions (e.g., anthrax), but risk-benefit must be carefully assessed.
Achromycin (tetracycline) should be administered on an empty stomach (1 hour before or 2 hours after meals) to ensure adequate absorption. Avoid concurrent use with dairy products, antacids, iron, calcium, magnesium, or bismuth subsalicylate as they chelate tetracycline and reduce absorption. Tetracycline can cause photosensitivity; advise patients to avoid prolonged sun exposure and use sunscreen. It is contraindicated in pregnancy (risk of hepatotoxicity and fetal bone/teeth discoloration), lactation, and children under 8 years (permanent tooth discoloration and bone growth inhibition). Monitor for signs of superinfection, especially Clostridium difficile-associated diarrhea. Tetracycline may increase the effect of warfarin; monitor INR closely.
ACTICLATE (doxycycline hyclate) is a tetracycline antibiotic. Avoid concomitant use with antacids, dairy products, or iron supplements as they chelate doxycycline, reducing absorption. Administer with a full glass of water and avoid lying down for 30 minutes to reduce esophageal irritation. Photosensitivity is common; advise sun avoidance and sunscreen use. Do not use in children <8 years or during pregnancy/lactation due to tooth discoloration and bone growth inhibition. Monitor for pseudomembranous colitis and superinfection.
Take this medication on an empty stomach, at least 1 hour before or 2 hours after meals.,Do not take with dairy products, antacids, iron supplements, or calcium supplements; separate by at least 2-3 hours.,Avoid excessive sunlight or tanning beds; use sunscreen and wear protective clothing to prevent severe sunburn.,Complete the full course of treatment even if you feel better; do not skip doses.,Notify your doctor immediately if you develop watery or bloody diarrhea, rash, headache, blurred vision, or signs of infection worsening.,Do not use if you are pregnant, planning to become pregnant, or breastfeeding; this medication can harm the unborn baby or nursing infant.,Keep out of reach of children; expired tetracycline can cause kidney damage.
Take doxycycline exactly as prescribed. Do not skip doses or stop early even if you feel better.,Take with a full glass of water. Avoid lying down for at least 30 minutes after taking to prevent esophageal irritation.,Avoid taking with milk, yogurt, cheese, or calcium-fortified foods. Also avoid antacids, iron, and bismuth subsalicylate within 2 hours of doxycycline.,Use sunscreen and protective clothing; doxycycline increases sensitivity to sunlight and can cause severe sunburn.,If you miss a dose, take it as soon as you remember unless it is near the time of the next dose. Do not double the dose.,Report persistent diarrhea, severe headache, vision changes, or allergic reactions (rash, swelling) to your healthcare provider immediately.
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 ACHROMYCIN vs ACTICLATE, answered by our medical review team.
ACHROMYCIN is a Tetracycline Antibiotic that works by Tetracycline antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-t RNA from binding to the A site.. ACTICLATE is a Tetracycline Antibiotic that works by Inhibits P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), thereby increasing intestinal absorption and decreasing clearance of substrates; also inhibits CYP3A4 isoenzymes, reducing metabolism of CYP3A4 substrates.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACHROMYCIN and ACTICLATE depend on the specific clinical indication. These are both Tetracycline Antibiotic agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ACHROMYCIN is: 250-500 mg orally every 6 hours or 500 mg intravenously every 12 hours.. The standard adult dose of ACTICLATE is: 100 mg orally twice daily (12 hours apart) on an empty stomach (1 hour before or 2 hours after meals). Avoid milk, antacids, iron, calcium, magnesium, and zinc within 2 hours of administration.. 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 ACHROMYCIN and ACTICLATE 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. ACHROMYCIN is classified as Category C. ACHROMYCIN (tetracycline) is classified as FDA Pregnancy Category D. First trimester: Associated with minor malformations, but risk is low. Second and third trimesters: Exposure ca. ACTICLATE is classified as Category C. FDA Pregnancy Category D. Tetracyclines, including doxycycline (active ingredient in ACTICLATE), can cause fetal harm when administered to a pregnant woman. Use during tooth develo. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.