Single-dose pharmacokinetics and pharmacodynamics assessment of oestriol and trimegestone containing vaginal rings in healthy women with childbearing potential

First-in-human study to assess the pharmacokinetics, tolerability, and safety of single-dose oxybutynin hydrochloride administered via a microprocessor-controlled intravaginal ring

Polymeric drug-releasing vaginal rings are useful for both local and systemic administration of drugs via the intravaginal route. Typically, they provide continuous sustained or controlled release of drug(s) over extended time periods, thereby avoiding overdose and improving adherence. This first-in-human study (EudraCT number: 2020-0050044-30) evaluated the pharmacokinetics, safety, and tolerability of a single dose of oxybutynin administered by a novel microprocessor-controlled vaginal ring (MedRing). Eight healthy female subjects received an electronically controlled single intravaginal dose of 3 mg oxybutynin hydrochloride (100 mg/mL) dissolved in 1:1 water/propylene glycol administered via MedRing. Following dosing, MedRing was kept in situ for up to 6 h. Blood samples were collected 1 h prior to oxybutynin dosing and subsequently at regular intervals post-dose for the assessment of plasma concentrations of oxybutynin and its active metabolite N-desethyloxybutynin. The results showed that MedRing efficiently administered oxybutynin via the intravaginal route, resulting in plasma oxybutynin levels comparable to orally administered oxybutynin. The mean ± standard deviation pharmacokinetic parameters for oxybutynin were C_max 5.4 ± 2.7 ng/mL, AUC_inf 34.9 ± 17.4 h ng/mL, t_1/2 8.5 ± 3.5 h and for N-desethyloxybutynin were C_max 3.9 ± 2.5 ng/mL, AUC_inf 51.1 ± 43.1 h ng/mL, t_1/2 7.7 ± 5.9 h. No serious adverse events were reported. The study demonstrates that intravaginal administration of oxybutynin hydrochloride using the MedRing device was well tolerated.

Vaginal ring acceptability: A systematic review and meta-analysis of vaginal ring experiences from around the world

OBJECTIVE

The vaginal ring (ring) is a female-initiated, long-acting drug delivery system for different indications, including HIV prevention. Our aim was to provide evidence for acceptability of the vaginal ring across indications to support dapivirine and multipurpose prevention technology ring introduction and roll out.

STUDY DESIGN

This systematic review and meta-analysis followed PRISMA guidelines. We searched PubMed, Web of Science, Embase, and grey literature for publications reporting favorable ring acceptability and secondary outcomes involving actual ring use (comfort, ease of ring use, ring comfort during sex, expulsions, and vaginal symptoms) or hypothetical acceptability for any indication published January 1, 1970-June 15, 2021. We estimated random-effects pooled prevalence, assessing between-study variation using meta-regression.

RESULTS

Of 2,234 records, we included 123 studies with 40,434 actual and hypothetical ring users. The primary outcome assessment included 50 studies with 60 ring subgroups totaling 19,271 ring users. The favorable acceptability pooled prevalence was 85.6% (95%CI 81.3, 89.0), while hypothetical acceptability among non-ring users was 27.6% (95%CI 17.5, 40.5). In meta-regression, acceptability was higher in menopause (95.4%; 95%CI 88.4, 98.2) compared to contraceptive rings (83.7%; 95%CI 75.6, 89.5). Acceptability was lower in pharmacokinetic studies (50%; 95%CI 22.1, 77.9) compared to RCTs (89.5%; 95%CI 85.8.92.4) and in studies assessing acceptability at ≥12 months (78.5%; 95%CI 66.5, 87.1) versus studies assessing acceptability at <3 months (91.9%; 95%CI 83.7, 96.1). European (90.6%; 95%CI 83.9, 94.7), Asian (97.1%; 95%CI 92.0, 99.0), and multi-region studies (93.5%; 95%CI 84.6, 97.4) reported more favorable acceptability compared to African studies (59.4%; 95%CI 38.3, 77.5). Secondary outcomes were similarly favorable, including ring comfort (92.9%; 95%CI 89.2, 95.4), ease of use (90.9%; 95%CI 86.5, 94.0), and comfort during sex (82.7%; 95%CI 76.4, 87.6). Limitations include inconsistent outcome definitions and unmeasured factors affecting acceptability.

CONCLUSIONS

Women who used vaginal rings reported they were acceptable across indications geographic regions and indications. Policy makers should consider the ring as an important option for pregnancy and HIV prevention drug development.

IMPLICATIONS

This review found favorable acceptability among vaginal ring users across indications and geographic areas, in contrast to low hypothetical acceptability among non-users. Vaginal rings are an important drug delivery system for pregnancy and HIV preventions, and scale-up should plan to address initial hesitancy among new users.