Cervidil Vaginal Insert (Forest)

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DESCRIPTION

Dinoprostone vaginal insert is a thin, flat, polymeric slab which is rectangular in shape with rounded corners contained within the pouch of a knitted polyester retrieval system, an integral part of which is a long tape. Each slab is buff colored, semitransparent and contains 10 mg of dinoprostone. The hydrogel insert is contained within the pouch of an off-white knitted polyester retrieval system designed to aid retrieval at the end of the dosing interval. The finished product is a controlled release formulation which has been found to release dinoprostone in vivo at a rate of approximately 0.3 mg/hr.

The chemical name for dinoprostone (commonly known as prostaglandin E ₂ or PGE ₂ ) is 11(alpha), 15S-dihydroxy-9-oxo-prosta-5Z, 13E-dien-1-oic acid and the structural formula is represented below:

The molecular formula is C ₂₀ H ₃₂ O ₅ and its molecular weight is 352.5. Dinoprostone occurs as a white to off-white crystalline powder. It has a melting point within the range of 65° to 69°C. Dinoprostone is soluble in ethanol and in 25% ethanol in water. Each insert contains 10 mg of dinoprostone in 241 mg of a cross-linked polyethylene oxide/urethane polymer which is a semi-opaque, beige colored, flat rectangular slab measuring 29 mm by 9.5 mm and 0.8 mm in thickness. The insert and its retrieval system, made of polyester yarn, are non-toxic and when placed in a moist environment, absorb water, swell, and release dinoprostone.

CLINICAL PHARMACOLOGY

Dinoprostone (PGE ₂ ) is a naturally-occurring biomolecule. It is found in low concentrations in most tissues of the body and functions as a local hormone ( 1-3 ). As with any local hormone, it is very rapidly metabolized in the tissues of synthesis (the half-life estimated to be 2.5-5 minutes). The rate limiting step for inactivation is regulated by the enzyme 15-hydroxyprostaglandin dehydrogenase (PGDH) ( 1 , 4 ). Any PGE ₂ that escapes local inactivation is rapidly cleared to the extent of 95% on the first pass through the pulmonary circulation ( 1 , 2 ).

In pregnancy, PGE ₂ is secreted continuously by the fetal membranes and placenta and plays an important role in the final events leading to the initiation of labor ( 1 , 2 ). It is known that PGE ₂ stimulates the production of PGF ₂ (alpha) which in turn sensitizes the myometrium to endogenous or exogenously administrated oxytocin. Although PGE ₂ is capable of initiating uterine contractions and may interact with oxytocin to increase uterine contractility, the available evidence indicates that, in the concentrations found during the early part of labor, PGE ₂ plays an important role in cervical ripening without affecting uterine contractions ( 5-7 ). This distinction serves as the basis for considering cervical ripening and induction of labor, usually by the use of oxytocin ( 8-10 ), as two separate processes.

PGE ₂ plays an important role in the complex set of biochemical and structural alterations involved in cervical ripening. Cervical ripening involves a marked relaxation of the cervical smooth muscle fibers of the uterine cervix which must be transformed from a rigid structure to a softened, yielding and dilated configuration to allow passage of the fetus through the birth canal ( 11-13 ). This process involves activation of the enzyme collagenase, which is responsible for digestion of some of the structural collagen network of the cervix ( 1 , 14 ). This is associated with a concomitant increase in the amount of hydrophilic glycosaminoglycan, hyaluronic acid, and a decrease in dermatan sulfate ( 1 ). Failure of the cervix to undergo these natural physiologic changes, usually assessed by the method described by Bishop ( 15 , 16 ), prior to the onset of effective uterine contractions, results in an unfavorable outcome for successful vaginal delivery and may result in fetal compromise. It is estimated that in approximately 5% of pregnancies the cervix does not ripen normally ( 17 ). In an additional 10-11% of pregnancies, labor must be induced for medical or obstetric reasons prior to the time of cervical ripening ( 17 ).

The delivery rate of PGE ₂ in vivo is about 0.3 mg/hour over a period of 12 hours. The controlled release of PGE ₂ from the hydrogel insert is an attempt to provide sufficient quantities of PGE ₂ to the local receptors to satisfy hormonal requirements. In the majority of patients, these local effects are manifested by changes in the consistency, dilatation and effacement of the cervix as measured by the Bishop score. Although some patients experience uterine hyperstimulation as a result of direct PGE ₂ - or PGF ₂ (alpha)-mediated sensitization of the myometrium to oxytocin, systemic effects of PGE ₂ are rarely encountered. The insert is fitted with a biocompatible retrieval system which facilitates removal at the conclusion of therapy or in the event of an adverse reaction.

No correlation could be established between PGE ₂ release and plasma concentrations of PGE _m . The relative contributions of endogenously and exogenously released PGE ₂ to the plasma levels of the metabolite PGE _m could not be determined. Moreover, it is uncertain as to whether the measured concentrations of PGE _m reflect the natural progression of PGE _m concentrations in blood as birth approaches or to what extent the measured concentrations following PGE ₂ administration represent an increase over basal levels that might be measured in control patients.

INDICATIONS AND USAGE

Cervidil Vaginal Insert (dinoprostone, 10 mg) is indicated for the initiation and/or continuation of cervical ripening in patients at or near term in whom there is a medical or obstetrical indication for the induction of labor.

CONTRAINDICATIONS

Cervidil is contraindicated in:

• Patients with known hypersensitivity to prostaglandins.
• Patients in whom there is clinical suspicion or definite evidence of fetal distress where delivery is not imminent.
• Patients with unexplained vaginal bleeding during this pregnancy.
• Patients in whom there is evidence or strong suspicion of marked cephalopelvic disproportion.
• Patients in whom oxytocic drugs are contraindicated or when prolonged contraction of the uterus may be detrimental to fetal safety or uterine integrity, such as previous cesarean section or major uterine surgery (see PRECAUTIONS and ADVERSE REACTIONS ).
• Patients already receiving intravenous oxytocic drugs.
• Multipara with 6 or more previous term pregnancies.

WARNINGS

For hospital use only

Cervidil should be administered only by trained obstetrical personnel in a hospital setting with appropriate obstetrical care facilities.

PRECAUTIONS

1.   General Precautions:   Since prostaglandins potentiate the effect of oxytocin, Cervidil must be removed before oxytocin administration is initiated and the patient's uterine activity carefully monitored for uterine hyperstimulation. If uterine hyperstimulation is encountered or if labor commences, the vaginal insert should be removed. Cervidil should also be removed prior to amniotomy.

Cervidil is contraindicated when prolonged contraction of the uterus may be detrimental to fetal safety and uterine integrity. Therefore, Cervidil should not be administered to patients with a history of previous cesarean section or uterine surgery given the potential risk for uterine rupture and associated obstetrical complications.

Caution should be exercised in the administration of Cervidil for cervical ripening in patients with ruptured membranes, in cases of non-vertex, or non-singleton presentation, and in patients with a history of previous uterine hypertony, glaucoma, or a history of childhood asthma, even though there have been no asthma attacks in adulthood.

Uterine activity, fetal status and the progression of cervical dilatation and effacement should be carefully monitored whenever the dinoprostone vaginal insert is in place. Any evidence of uterine hyperstimulation, sustained uterine contractions, fetal distress, or other fetal or maternal adverse reactions, should be a cause for consideration of removal of the insert.

2.  Drug Interactions:   Cervidil may augment the activity of oxytocic agents and their concomitant use is not recommended. A dosing interval of at least 30 minutes is recommended for the sequential use of oxytocin following the removal of the dinoprostone vaginal insert. No other drug interactions have been identified.

3.  Carcinogenesis, Mutagenesis, Impairment of Fertility: Long-term carcinogenicity and fertility studies have not been conducted with Cervidil (dinoprostone) Vaginal Insert. No evidence of mutagenicity has been observed with prostaglandin E ₂ in the Unscheduled DNA Synthesis Assay, the Micronucleus Test, or Ames Assay.

4.  Pregnancy, Teratogenic Effects:

Pregnancy Category C:

Prostaglandin E ₂ has produced an increase in skeletal anomalies in rats and rabbits. No effect would be expected clinically, when used as indicated, since Cervidil (dinoprostone) Vaginal Insert is administered after the period of organogenesis. Prostaglandin E ₂ has been shown to be embryotoxic in rats and rabbits, and any dose that produces sustained increased uterine tone could put the embryo or fetus at risk.

5.  Pediatric Use:   The safety and efficacy of Cervidil has been established in women of a reproductive age and women who are pregnant. Although safety and efficacy has not been established in pediatric patients, safety and efficacy are expected to be the same for adolescents.

ADVERSE REACTIONS

Cervidil is well tolerated. In placebo-controlled trials in which 658 women were entered and 320 received active therapy (218 without retrieval system, 102 with retrieval system), the following events were reported.

In Postmarketing Experience Reports, uterine rupture has been reported in association with the use of Cervidil.

Drug related fever, nausea, vomiting, diarrhea, and abdominal pain were noted in less than 1% of patients who received Cervidil.

In study 101-801 (with the retrieval system) cases of hyperstimulation reversed within 2 to 13 minutes of removal of the product. Tocolytics were required in one of the five cases.

In cases of fetal distress, when product removal was thought advisable there was a return to normal rhythm and no neonatal sequelae.

Five minute Apgar scores were 7 or above in 98.2% (646/658) of studied neonates whose mothers received Cervidil. In a report of a 3 year pediatric follow-up study in 121 infants, 51 of whose mothers received Cervidil, there were no deleterious effects on physical examination or psychomotor evaluation ( 18 ).

DRUG ABUSE AND DEPENDENCE

No drug abuse or dependence has been seen with the use of Cervidil.

OVERDOSAGE

Cervidil is used as a single dosage in a single application. Overdosage is usually manifested by uterine hyperstimulation which may be accompanied by fetal distress and is responsive to removal of the insert. Other treatment must be symptomatic since, to date, clinical experience with prostaglandin antagonists is insufficient.

The use of beta-adrenergic agents should be considered in the event of undesirable increased uterine activity.

DOSAGE AND ADMINISTRATION

The dosage of dinoprostone in the vaginal insert is 10 mg designed to be released at approximately 0.3 mg/hour over a 12 hour period. Cervidil should be removed upon onset of active labor or 12 hours after insertion.

One Cervidil is placed transversely in the posterior fornix of the vagina immediately after removal from its foil package. The insertion of the vaginal insert does not require sterile conditions. The vaginal insert must not be used without its retrieval system. There is no need for previous warming of the product. A minimal amount of K-Y® jelly (or other water-miscible lubricant) may be used to assist in insertion of Cervidil. Care should be taken not to permit excess contact or coating with the lubricant and thus prevent optimal swelling and release of dinoprostone from the vaginal insert. Patients should remain in the recumbent position for 2 hours following insertion, but thereafter may be ambulatory.

HOW SUPPLIED

Cervidil (NDC 0456-4123-63) contains 10 mg dinoprostone. The product is wound and enclosed in an aluminum/polyethylene pack.

Store in a freezer: between -20°C and -10°C (-4°F and 14°F). Cervidil is packed in foil and is stable when stored in a freezer for a period of three years. Vaginal inserts exposed to high humidity will absorb moisture from the air and thereby alter the release characteristics of dinoprostone. Once used, the vaginal insert should be discarded.

CLINICAL STUDIES

REFERENCES

1. Physiology of Labor. In: Williams Obstetrics. Eds. Pritchard, J.A., MacDonald, P.C., and Gant, N.F. Appleton-Century-Crofts, Conn, Pp 295-321, (1985).
   
   
2. Rall, T.W. and Schliefer, L.S. Oxytocin, prostaglandin, ergot alkaloids, and other drugs; tocolytics agents, In: The Pharmacological Basis of Therapeutics. Eds. Gilman, A.G., Goodman, L.S., Rall, T.W., and Murad, F. MacMillan Publ. Co., New York, Pp 926-945, (1985).
   
   
3. Casey, M.L. and MacDonald, P.C. The initiation of labor in women: Regulation of phospholipid and arachidonic acid metabolism and of prostaglandin production. Semin. Perinat. 10: 270-275, (1986).
   
   
4. Casey, M.L., MacDonald, P.C. and Mitchell, M.D. Stimulation of prostaglandin E ₂ production in amnion cells in culture by a substance(s) in human fetal urine. Biochem. Biophys. Res. Comm. 114:1056, (1983).
   
   
5. Olson, C.M., Lye, S.J., Skinner, K., and Challis, J.R.G. Prostanoid concentrations in maternal/fetal plasma and amniotic fluid and intrauterine tissue prostanoid output in relation to myometrial contractility during the onset of Endocrinology. 116: 389-397, (1985).
   
   
6. Ledger, W.L., Ellwood, D.A., and Taylor, M.J. Cervical softening in late pregnant sheep by infusion of prostaglandin E-2 into cervical artery. J. Reprod. Fert. 69, 511-515, (1983).
   
   
7. Olson, D.M., Lye, S.J., Skinner, K., and Challis, J.R.G. Early changes in prostaglandin concentrations in ovine maternal and fetal plasma, amniotic fluid and from dispersed cells of intrauterine tissues before the onset of ACTH-induced pre-term labor. J. Reprod. Fert. 71: 45-55, (1984).
   
   
8. Caldero-Garcia, R. and Posiero, J. Oxytocin and the contractility of the human uterus, Ann, N.Y. Acad. Sci. 75:813, (1959).
   
   
9. Posiero, J. and Noriega-Guerra, L. Dose-response relationships in uterine effects of oxytocin infusion. Oxytocin. Eds., Caldero-Garcia, R. and Heller, J. Pergamon Press, New York, (1961).
   
   
10. Cibils, L. Enhancement of induction of labor. In: Risks in the Practice of Modern Obstetrics. Aldjem, S. Ed. Mosby Publishing, St. Louis, (1972).
    
    
11. Bryman, I., Lindblom, B., and Norstrom, A. Extreme sensitivity of cervical musculature to prostaglandin E ₂ in early pregnancy. Lancet, 2:1471, (1982).
    
    
12. Thiery, M. Induction of labor with prostaglandins. In: Human Parturition. Eds. Keirse, M.J.N.C., Anderson, A.B.M.; and Gravenhorst, J.B. Martinus Nijhoff Publ., Boston, 155-164, (1979).
    
    
13. Thiery, M. and Amy, J.J. Induction of labor with prostaglandins. In: Advances in Prostaglandin Research. Prostaglandin and Reproduction. Karim, S.M.M., Ed., MTP, Lancaster, Pp. 149-228, (1975).
    
    
14. MacLennan, A.H., Katz, M., and Creasey, R. The morphologic characteristics of cervical ripening induced by the hormones relaxin and prostaglandin F ₂ in a rabbit model. Am. J. Obstet. Gynecol, 152: 910696, (1985).
    
    
15. Bishop, E. Elective induction of labor. Obstet. & Gynecol. 5: 519-527, (1955).
    
    
16. Bishop, E. Pelvic scoring for elective induction. Obstet. & Gynecol. 24: 266-268. (1969).
    
    
17. Thiery, M. Preinduction cervical ripening. In: Obstetrics and Gynecology Annual, Vol. 12 Ed. Wynn, R.M. Appleton-Century-Crofts, New York, Pp. 103-146, (1983).
    
    
18. MacKenzie, I.; Information on File: Controlled Therapeutics (Scotland).

Mfg by:

Controlled Therapeutics

East Kilbride, Scotland G74 5PB

Made in the U.K.

Distributed by:

FOREST PHARMACEUTICALS, INC.

Subsidiary of Forest Laboratories, Inc.

St. Louis, MO 63045 USA

Rev. 5/01RMC226

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