Doxycycline Barbiturates

On the other hand, the analgesic phenylbutazone, the antidepressant paroxetine, tetracycline antibiotics doxycycline and chlorotetracycline, the antibiotics tilmico-sin, danofloxacin, enoxacin, nifuroxazide, the (3-blockers betaxolol, carazolol, pindolol, the (3-agonist clenbuterol, barbiturates, the antihypertensive lisinopril, and the drug to treat cancer tamoxifen were never detected. 

Drugs that may affect barbiturates include alcohol, charcoal, chloramphenicol, MAO inhibitors, rifampin, and valproic acid. Drugs that may be affected by barbiturates include acetaminophen, anticoagulants, beta blockers, carbamazepine, chloramphenicol, clonazepam, oral contraceptives, corticosteroids, digitoxin, doxorubicin, doxycycline, felodipine, fenoprofen, griseofulvin, hydantoins, methoxyflurane, metronidazole, narcotics, phenmetrazine, phenylbutazone, quinidine, theophylline, and verapamil. 

Rifampin is known to induce the hepatic microsomal enzymes that metabolize various drugs such as acetaminophen, oral anticoagulants, barbiturates, benzodiazepines, beta blockers, chloramphenicol, clofibrate, oral contraceptives, corticosteroids, cyclosporine, disopyramide, estrogens, hydantoins, mexiletine, quinidine, sulfones, sulfonylureas, theophyllines, tocainide, verapamil, digoxin, enalapril, morphine, nifedipine, ondansetron, progestins, protease inhibitors, buspirone, delavirdine, doxycycline, fluoroquinolones, losartan, macrolides, sulfonylureas, tacrolimus, thyroid hormones, TCAs, zolpidem, zidovudine, and ketoconazole. The therapeutic effects of these drugs may be decreased. 

HA, mild pain Action Nonnarco tic analgesic w/ barbiturate Dose 1—2 tabs or caps PO q4-6h PRN i in renal/hepatic impair 4 g/24 h APAP max Caution [C, D, +] Alcoholic liver Dz Contra G6PD deficiency Disp Caps, Liq, tabs SE Drowsiness, dizziness, hangover effect Interactions T Effects OF benzodiazepines, opiate analgesics, sedatives/hypnotics, EtOH, methylphenidate hydrochloride i effects OF MAOIs, TCAs, corticosteroids, theophylline, OCPs, BBs, doxycycline EMS See Acetaminophen may impair coordination, monitor for depression concurrent EtOH use T CNS depression butalbital is habit forming... 

DOXYCYCLINE ANTIEPILEPTICS -BARBITURATES, CARBAMAZEPINE, PHENYTOIN i doxycydine levels, with risk of therapeutic failure Induction of hepatic metabolism Monitor for i clinical efficacy and t dose as required... 

Doxycycline at recommended doses does not accumulate significantly in patients with renal failure and thus is one of the safest of the tetracyclines for use in patients with renal impairment. The drug is excreted in the feces. Its half-life may be significantly shortened by concurrent therapy with barbiturates, phenytoin, rifampin, or other inducers of hepatic microsomal enzymes. 

The serum levels of doxycycline are reduced and may fall below the accepted minimum inhibitory concentration in patients receiving long-term treatment with barbiturates, phenytoin or car-bamazepine. Other tetracyclines do not appear to be affected. 

Similar results were found in 16 other patients taking various combinations of phenytoin, carbamazepine, primidone or phenobarbital. The serum doxycycline levels of almost all of them fell below 0.5 micrograms/mL during the 12 to 24 hour period following their last dose of doxycycline 100 mg. Tetracycline, methacycline, oxytetracycline, demeclocycline and chlortetracycline levels were not significantly affected by these antiepilepties. Other studies confirm this interaction between some barbiturates (amobarbital, pentobarbital, phenobarbital) and doxycycline. ... 

Uncertain. These antiepileptics and barbiturates are known enzyme inducers and it seems probable that they increase the metabolism of the doxycycline by the liver, thereby increasing its clearance from the body. 

NeuvCTien PJ, Penttila O. Interaction between doxycycline and barbiturates. BMJ (1974) 1, 535-6. 

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