Drug Interactions between isoniazid / pyrazinamide / rifampin and quinestrol

Using isoniazid together with rifAMPin can cause serious side effects that may affect your liver. You should avoid or limit the use of alcohol while being treated with these medications. Your doctor may already be aware of the risks but has determined that this is the best course of treatment for you, has taken appropriate precautions, and is monitoring you closely for any potential complications. If you develop severe liver problems, you may need a dose adjustment or an interruption in therapy. Call your doctor immediately if you have fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, abdominal pain, dark colored urine, light colored stools, and/or yellowing of the skin or eyes, as these may be signs and symptoms of liver damage. Talk to your healthcare provider if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Ask your doctor before using rifAMPin together with pyrazinamide. This can cause damage to the liver. Liver function and drug levels in the blood may be monitored with blood tests during treatment. Call your doctor if you experience fever, rash, loss of appetite, nausea, vomiting, fatigue, right upper abdominal pain, dark urine, and jaundice. You may need a dose adjustment or special tests to safely take both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

RifAMPin may reduce the blood levels and effects of quinestrol. If you are using quinestrol for birth control, you may be at increased risk for pregnancy or breakthrough bleeding. You should discuss the use of alternative or additional methods of birth control with your healthcare provider. If you take quinestrol for another purpose, such as hormone replacement for menopause, notify your doctor if your medication is no longer controlling your symptoms or you experience abnormal bleeding. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Isoniazid may cause liver problems and using it with other medications that can also affect the liver, such as pyrazinamide, may increase that risk. You should avoid or limit the use of alcohol while being treated with these medications. Your doctor may already be aware of the risks but has determined that this is the best course of treatment for you, has taken appropriate precautions, and is monitoring you closely for any potential complications. If you develop severe liver problems, you may need a dose adjustment or an interruption in therapy. Call your doctor immediately if you have fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, abdominal pain, dark colored urine, light colored stools, and/or yellowing of the skin or eyes, as these may be signs and symptoms of liver damage. Talk to your healthcare provider if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumer information for this interaction is not currently available.

MONITOR: The effectiveness of estrogen-containing medications may be impaired by concomitant treatment with antimicrobial agents. During metabolism, the estrogen component is conjugated, resulting in sulfation or glucuronidation of the original estrogenic steroid. The conjugates reach the intestine by way of the bile duct where hydrolytic enzymes of intestinal bacteria break down the conjugates into free, active estrogenic hormone. The active hormone is then available for enterohepatic cycling, which helps to maintain estrogen levels. It is important to note that the progestin component of a combined hormonal product does not undergo this process. It has been suggested that broad-spectrum antibiotics may reduce the effectiveness of estrogen-containing contraceptives because of their potential to reduce the number of intestinal bacteria and thus interfere with enterohepatic cycling of estrogen. Most of the research regarding this possible interaction has been done with oral contraceptives, but all estrogens appear to undergo enterohepatic recirculation so theoretically this interaction is a possibility with estrogen containing medications that are being used for alternative purposes. However, the risk appears to be small, and supportive data are primarily limited to anecdotal evidence from case reports and findings from uncontrolled or poorly controlled studies. Most antimicrobials, with the exception of enzyme inducing medications like the rifamycins and possibly griseofulvin, have not been shown to significantly increase the clearance of oral contraceptive estrogens. It is possible that a small number of women may be more sensitive to the effects of antimicrobials on estrogen disposition in vivo, but risk factors or genetic predispositions have yet to be identified.

MANAGEMENT: If a person is using estrogen for a purpose other than contraception, it is important to note that there is a theoretical possibility of lower levels of systemic estrogen available during treatment with an antibiotic due to interference with enterohepatic cycling. These patients should be counseled to report any changes in efficacy of the hormonal product to their healthcare provider. In the case of contraception specifically, the Centers for Disease Control and Prevention do not consider most broad-spectrum antibiotics to significantly interfere with the effectiveness of combined hormonal contraception. However, the manufacturers of certain combined hormonal contraceptives and/or certain antibiotics do recommend using a back-up method of birth control for varying amounts of time; therefore, consulting the product labeling of each medication involved is advised. Some illnesses, as well as some antibiotics, may cause nausea, vomiting, and/or diarrhea. If the patient vomits within a few hours of taking an oral contraceptive pill, consult the product labeling for instructions on what to do in the event of a missed pill. Some authorities recommend a back-up method of birth control if an individual has persistent vomiting or diarrhea.