Doxycycline

Both acitretin and tetracyclines can cause increased intracranial pressure; concurrent use should be avoided.

Both isotretinoin and tetracyclines can cause increased intracranial pressure and pseudotumor cerebri; concurrent use should be avoided.

Concurrent use of tetracycline and methoxyflurane has been reported to result in fatal renal toxicity.

7 DRUG INTERACTIONS • Patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage ( 7.1 ) • Avoid co-administration of tetracyclines with penicillin ( 7.2 ) • Absorption of tetracyclines, including doxycycline hyclate delayed-release tablets, is impaired by antacids containing aluminum, calcium, or magnesium, bismuth subsalicylate and iron-containing preparations ( 7.3 ) • Concurrent use of tetracyclines, including doxycycline hyclate delayed-release tablets, may render oral contraceptives less effective ( 7.4 ) • Barbiturates, carbamazepine and phenytoin decrease the half-life of doxycycline ( 7.5 ) 7.1 Anticoagulant Drugs Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage. 7.5 Barbiturates and Anti-Epileptics Barbiturates, carbamazepine, and phenytoin decrease the half-life of doxycycline.

Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines in conjunction with penicillin.

Phenobarbital shortens the half-life of doxycycline for up to 2 weeks after discontinuation. Clinical response should be monitored closely.

Phenobarbital shortens the half-life of doxycycline for up to 2 weeks after discontinuation; clinical response should be monitored closely.

Doxycycline Administered with rifampin (10 mg/kg daily) Decrease exposure Irinotecan Administered with an antibiotic regimen including rifampin (450 mg/day), isoniazid (300 mg/day), and streptomycin (0.5 g/day) IM Prevention or Management: Avoid the use of rifampin, a strong CYP3A4 inducer, if possible.

Drug Interactions Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage. Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines in conjunction with penicillin. Absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, and iron-containing preparations.

Absorption of tetracyclines is impaired by antacids containing aluminum.

Antacids containing calcium impair the absorption of tetracyclines.

Antacids impair absorption of tetracyclines.

Absorption of tetracyclines is impaired by antacids containing magnesium.

Ascorbic acid may decrease the activity of doxycycline. Standard monitoring of antibiotic efficacy is warranted.

Thiamine, riboflavin, pyridoxine, niacinamide, and ascorbic acid decrease the antibiotic activity of doxycycline.

Barbiturates shorten the half-life of doxycycline, thereby lowering doxycycline concentration in the body.

Absorption of tetracyclines is impaired by bismuth subsalicylate.

Absorption of tetracyclines is impaired by antacids containing calcium.

Carbamazepine shortens the half-life of doxycycline, thereby lowering doxycycline concentration in the body.

Doxycycline must be taken at least 1 hour before ferric citrate to avoid reduced bioavailability.

Ferric maltol may decrease bioavailability of doxycycline. Separate administration by at least 4 hours and monitor clinical response.

Absorption of tetracyclines is impaired by iron-containing preparations.

Absorption of tetracyclines is impaired by proton pump inhibitors.

Thiamine, riboflavin, pyridoxine, niacinamide, and ascorbic acid decrease doxycycline antibiotic activity.

Tetracyclines depress plasma prothrombin activity; patients on anticoagulant therapy may require downward adjustment of anticoagulant dosage.

Concurrent use of tetracycline may render oral contraceptives less effective.

Barbiturates shorten doxycycline half-life for up to 2 weeks after discontinuation. Clinical response should be monitored closely if given concurrently.

Phenytoin shortens the half-life of doxycycline, thereby lowering doxycycline concentration in the body.

QT interval prolonging drug. Coadministration with VANFLYTA may further increase incidence of QT prolongation. More frequent ECG monitoring recommended.

Rifapentine may increase metabolism and decrease activity. Dosage adjustment may be necessary.

Tetracyclines depress plasma prothrombin activity; patients may require downward adjustment of anticoagulant dosage.

Doxycycline should be taken at least 1 hour before sucroferric oxyhydroxide to avoid reduced bioavailability.

Serum concentrations of etonogestrel and ethinyl estradiol were not affected by concomitant administration in standard dosages.

Serum concentrations of etonogestrel and ethinyl estradiol were not affected by concomitant administration in standard dosages.

Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D Drugs whose level is decreased by phenytoin Anticoagulants Apixaban, dabigatran, edoxaban, rivaroxaban Antiepileptic drugs The effect of phenytoin on phenobarbital, valproic acid and sodium valproate serum levels is unpredictable.

Since both oral retinoids, including isotretinoin and acitretin, and the tetracyclines, primarily minocycline, can cause increased intracranial pressure, the concurrent use of an oral retinoid and a tetracycline should be avoided.

Warfarin Increased and decreased PT/INR responses have been reported when phenytoin is coadministered with warfarin Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D Drugs whose level is decreased by phenytoin Antiepileptic drugs a Carbamazepine, felbamate, lamotrigine, topiramate, oxcarbazepine Antilipidemic agents Atorvastatin, fluvastatin, simvastatin Antiviral agents Efavirenz, lopinavir/ritonavir, indinavir, nelfinavir, ritonavir, saquinavir Fosamprenavir: phenytoin when given with fosamprenavir alone may decrease the concentration of amprenavir, the active metabolite.