Drug Interactions between DisperMox and Valertest No 1
This report displays the potential drug interactions for the following 2 drugs:
- DisperMox (amoxicillin)
- Valertest No 1 (estradiol/testosterone)
Interactions between your drugs
amoxicillin estradiol
Applies to: DisperMox (amoxicillin) and Valertest No 1 (estradiol / testosterone)
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.
References
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- Back DJ, Breckenridge AM, MacIver M, et al. (1982) "The effects of ampicillin on oral contraceptive steroids in women." Br J Clin Pharmacol, 14, p. 43-8
- Neely JL, Abate M, Swinker M, D'Angio R (1991) "The effect of doxycycline on serum levels of ethinyl estradiol, norethindrone, and endogenous progesterone." Obstet Gynecol, 77, p. 416-20
- Joshi JV, Joshi UM, Sankholi GM, et al. (1980) "A study of interaction of low-dose combination oral contraceptive with ampicillin and metronidazole." Contraception, 22, p. 643-52
- Baciewicz AM (1985) "Oral contraceptive drug interactions." Ther Drug Monit, 7, p. 26-35
- Bint AJ, Burtt I (1980) "Adverse antibiotic drug interactions." Drugs, 20, p. 57-68
- Dossetor J (1975) "Drug interactions with oral contraceptives." Br Med J, 4, p. 467-8
- DeSano EA, Hurley SC (1982) "Possible interactions of antihistamines and antibiotics with oral contraceptive effectiveness." Fertil Steril, 37, p. 853-4
- Szoka PR, Edgren RA (1988) "Drug interactions with oral contraceptives: compilation and analysis of an adverse experience report database." Fertil Steril, 49(5 Suppl), s31-8
- Barnett ML (1985) "Inhibition of oral contraceptive effectiveness by concurrent antibiotic administration." J Periodontol, 56, p. 18-20
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- Bacon JF, Shenfield GM (1980) "Pregnancy attributable to interaction between tetracycline and oral contraceptives." Br Med J, 280, p. 293
- Fazio A (1991) "Oral contraceptive drug interactions: important considerations." South Med J, 84, p. 997-1002
- Back DJ, Orme ML (1990) "Pharmacokinetic drug interactions with oral contraceptives." Clin Pharmacokinet, 18, p. 472-84
- Back DJ, Tjia J, Martin C, Millar E, Mant T, Morrison P, Orme M (1991) "The lack of interaction between temafloxacin and combined oral contraceptive steroids." Contraception, 43, p. 317-23
- Orme ML, Back DJ (1986) "Interactions between oral contraceptive steroids and broad-spectrum antibiotics." Clin Exp Dermatol, 11, p. 327-31
- Wermeling DP, Chandler MH, Sides GD, Collins D, Muse KN (1995) "Dirithromycin increases ethinyl estradiol clearance without allowing ovulation." Obstet Gynecol, 86, p. 78-84
- Silber TJ (1983) "Apparent oral contraceptive failure associated with antibiotic administration." J Adolesc Health Care, 4, p. 287-9
- Bollen M (1995) "Use of antibiotics when taking the oral contraceptive pill." Aust Fam Physician, 24, p. 928-9
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- Weisberg E (1999) "Interactions between oral contraceptives and antifungals antibacterials - Is contraceptive failure the result?." Clin Pharmacokinet, 36, p. 309-13
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Drug and food interactions
estradiol food
Applies to: Valertest No 1 (estradiol / testosterone)
Coadministration with grapefruit juice may increase the bioavailability of oral estrogens. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. In a small, randomized, crossover study, the administration of ethinyl estradiol with grapefruit juice (compared to herbal tea) increased peak plasma drug concentration (Cmax) by 37% and area under the concentration-time curve (AUC) by 28%. Based on these findings, grapefruit juice is unlikely to affect the overall safety profile of ethinyl estradiol. However, as with other drug interactions involving grapefruit juice, the pharmacokinetic alterations are subject to a high degree of interpatient variability. Also, the effect on other estrogens has not been studied.
References
- Weber A, Jager R, Borner A, et al. (1996) "Can grapefruit juice influence ethinyl estradiol bioavailability?" Contraception, 53, p. 41-7
- Schubert W, Eriksson U, Edgar B, Cullberg G, Hedner T (1995) "Flavonoids in grapefruit juice inhibit the in vitro hepatic metabolism of 17B-estradiol." Eur J Drug Metab Pharmacokinet, 20, p. 219-24
Therapeutic duplication warnings
No warnings were found for your selected drugs.
Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.
See also
Drug Interaction Classification
Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. | |
No interaction information available. |
Further information
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