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Health - Interactions Between Benzodiazepines And The Oral Contraceptive Pill

Discussion in 'Benzodiazepines' started by Jatelka, Dec 21, 2006.

  1. Jatelka

    Jatelka Psychedelic Shepherdess Platinum Member & Advisor

    Reputation Points:
    Oct 16, 2005
    from U.K.
    SWIJ took benzos for some years, and only recently found out that the combined oral contraceptive pill interacted with benzodiazepines. What's more it seems that it interacts differently depending on the benzo.

    This is kind of a rush job, but she thought she'd list some abstracts for you's info. If anyYou has more info, it would be gratefully received.

    1) Lorazepam and oxazepam kinetics in women on low dose oral contraceptives (Abernethy et al) Clin Pharmacol Ther. 1983 May;33(5):628-32

    Women on low-dose estrogen oral contraceptives (OC) and drug-free control women matched for age, weight, and cigarette smoking habits, received single 2-mg IV doses of lorazepam or single 30-mg oral doses of oxazepam, two benzodiazepines metabolized by glucuronide conjugation. Kinetics were determined from multiple plasma concentrations measured during 48 hr after dosing. Mean kinetic variables for lorazepam in control and OC groups (n = 15 in each group) were: volume of distribution (Vd), 1.33 and 1.45 l/kg; elimination t1/2, 13.1 and 12.2 hr; total clearance, 1.25 and 1.50 ml/min/kg; free fraction in plasma, 10.3% and 10.3% unbound. For oxazepam, kinetic variables in the two groups (n = 14 and 17) were: Vd, 1.05 and 1.19 l/kg; t1/2, 7.6 and 7.2 hr; total clearance, 1.60 and 2.03 ml/min/kg; free fraction, 4.6% and 4.9% unbound. None of these differences were significant. Thus, metabolic clearance by glucuronidation of lorazepam and oxazepam is not significantly affected by OC, in contrast with the highly significant reduction in clearance of the oxidized benzodiazepine diazepam.

    2) Differential effects of oral contraceptive steroids on the metabolism of benzodiazepines (Patwharden et al) Hepatology. 1983 Mar-Apr;3(2):248-53.

    The effects of oral contraceptive steroids (OCS) on the disposition and elimination of lorazepam, oxazepam, and chlordiazepoxide were examined. Lorazepam and oxazepam are metabolized via glucuronidation while chlordiazepoxide is metabolized by oxidation in the liver. The disposition and elimination of lorazepam, oxazepam, and chlordiazepoxide was studied in females not taking OCS and females taking OCS (norethindrone acetate, 1 mg; ethinyl estradiol, 50 micrograms) for 6 months or more. The t1/2 (beta) for lorazepam was significantly reduced in women taking OCS (6.0 +/- 3.1 vs. 14.0 +/- 6.2 hr) (p less than 0.005) as compared to controls, and the t1/2 (beta) for oxazepam was reduced in women taking OCS (7.71 +/- 3.23 vs. 12.09 +/- 5.08 hr) as compared to controls, but did not reach statistical significance. The plasma clearance of both lorazepam and oxazepam was significantly increased in women taking OCS [(288.9 +/- 165.9 vs. 77.5 +/- 3.29 ml per min) (p less than 0.01) and (251.2 +/- 106.9 vs. 97.86 +/- 69.4 ml per min) (p less than 0.01), respectively] as compared to controls. The volumes of distribution of lorazepam and oxazepam were significantly increased in women taking OCS (p less than 0.05) while plasma binding of these drugs was similar in both groups. In contrast, the t1/2 (beta) of chlordiazepoxide was significantly prolonged (20.58 +/- 8.08 vs. 11.63 +/- 5.91 hr) (p less than 0.05), and the plasma clearance was significantly reduced (13.41 +/- 4.69 vs. 33.22 +/- 12.37 ml per min) (p less than 0.05) in the OCS group as compared to controls. The volumes of distribution of chlordiazepoxide were similar in both groups, and the plasma binding of chlordiazepoxide tended to be lower in the OCS group but did not reach statistical significance. We conclude that OCS exert a differential effect on the elimination of benzodiazepines, whereby oxidation of chlordiazepoxide is impaired while the glucuronidation of lorazepam and oxazepam is enhanced by OCS.

    3) Effect of oral contraceptives on triazolam, temazepam, alprazolam and lorazepam kinetics (Stoehr et al) Clin Pharmacol Ther. 1984 Nov;36(5):683-90

    Because benzodiazepines and oral contraceptives (OCs) are among the most widely prescribed drugs and have a potential for interaction, 2 parallel crossover studies were conducted to determine the effects of OCs on the elimination of the oxidized benzodiazepines triazolam (TRZ) and alprozolam (ALP) and the conjugated benzodiazepines temazepam (TMZ) and lorazepam (LOR). 20 healthy women taking OCs containing does of under 35 mcg of ethinyl estradiol for 3 months or more and 20 women matched for age, weight, and cigarette smoking received single oral doses of TRZ (.5 mg) and TMZ (30 mg) or ALP (1 mg) and LOR (2 mg). Treatments were seperated by 28 days to control for effects of menstural cycle on drug metabolism. Kinetics were determined as plasma concentrations during 48 hours after dosing. The data indicated that OCs differentially affect the elimination of the benzodiazepines studied. OCs inhibited the metabolism of ALP: the area under the curve (AUC) increased and the elimination rate constant was greater in users of OCs. For TRZ, which has an intermediate extraction ratio, the AUC was increased by OCs but not significantly so. OCs decreased the AUC for TMZ and the elimination rate constants for LOR and TMZ. The AUC of LOR was not affected by OCs. It was concluded that low-dose estrogen OCs may inhibit the metabolism of some conjugated benzodiazepines and accelerate the metabolism of some conjugated benzodiazepines, but the clinical implications are unclear. The relationship between plasma concentration and effect has not been determined for most benzodiazepines, but the results suggest that the time required to achieve steady-state concentrations would be longer and that there would be higher steady state concentrations of ALP in OC users. Because both TMZ and LOR are eliminated more rapidly by OC users, women taking OCs should achieve steady-state concentrations more rapidly than nonusers. Because TMZ clearance is increased by OCs, mean plasma concentration may be decreased. The usual 30 mg dose of TMZ may therefore be less effective as a hypnotic in OC users.

    4) Pharmacodynamic evaluation of the benzodiazepine-oral contraceptive interaction (Kroboth et al) Clin Pharmacol Ther. 1985 Nov;38(5):525-32

    The sedative, psychomotor, and memory effects of single oral doses of alprazolam (ALP), lorazepam (LOR), temazepam (TMP), and triazolam (TRZ) were evaluated in women taking oral contraceptives (OCs) and a comparable group of control women. Nine women taking OCs and 11 control women took doses of 1 mg ALP and 2 mg LOR and 10 OC users and 10 control women took 30 mg TMP and 0.5 mg TRZ on two occasions separated by 28 days. Minimal psychomotor impairment was noted after TMP. ALP, LOR, and TRZ produced greater performance impairment in the OC users. Correcting the maximum observed performance decrement for plasma concentration did not account for the differences between OC users and controls. After TMP, there was less sedation during the first 2 hours in OC users, who also had higher plasma TMP clearance. There were no differences in sedation between OC users and controls after ALP, LOR, and TRZ; however, there was less than 50% power to detect a 30% difference. Amnestic effects in OC users and controls did not differ after any of the four drugs. The observed patterns of anterograde amnesia were different, with the earliest and most pronounced recognition failure after TRZ (50% at 1.5 hours), while the LOR effect increased to a maximum (30%) 4 hours after dosing. Our data suggest that differences in benzodiazepine pharmacokinetics between OC users and control women do not account for observed differences in psychomotor impairment. Women taking OCs are more sensitive to the psychomotor effects of single oral doses of benzodiazepine.

    Last edited by a moderator: Sep 10, 2017
  2. _Dante_

    _Dante_ Silver Member

    Reputation Points:
    Mar 24, 2010
    from scotland
    This is a really interesting post, so I had to drag it up despite it being years old!

    What I was wondering was: this outlines how the benzo works differently if the woman is taking an oral contraceptive (OCs), but what about the affect on the effectiveness of the contraception??

    Does anyone know anything about this?
  3. pharmycologist

    pharmycologist Newbie

    Reputation Points:
    Mar 29, 2010
    from U.S.A.
    Interested OP. SWIM once read that oral contr. can increase peak plasma levels of benzos by a large percentage. He preceded to take one of his girlfirends pills to possibly experiment with this.

    When it came down to it, I was unable to ingest the estrogen packed little pill and threw it out instead of trying to for some potentiation, lol :)