Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services...
-
date post
18-Dec-2015 -
Category
Documents
-
view
214 -
download
0
Transcript of Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services...
![Page 1: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/1.jpg)
Misoprostol
Pharmacokinetics and Pharmacodynamics
Brian ClearyHRB PhD Scholar Health Services Research
TCD/CWIUH/RCSI25th February 2010
![Page 2: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/2.jpg)
Overview
• Pharmacokinetics– what the body does to the drug
• Clinical Implications• Pharmacodynamics
– what a drug does to the body
• Available products
![Page 3: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/3.jpg)
Pharmacokinetics
• study of the time course of drug and metabolite concentrations in different fluids, tissues, and excreta of the body, and of the mathematical relationships required to develop models to interpret such data
![Page 4: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/4.jpg)
Chemical Structure
www.3dchem.com/imagesofmolecules/Misoprostol.jpg
![Page 5: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/5.jpg)
Chemistry
• discovered in 1973• prostaglandin E1 analogue• slight structural modifications to:
– increase anti-secretory potency– increase duration of action (half life of
naturally occurring prostaglandins seconds)
– improve oral bioavailability– improve safety profile
![Page 6: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/6.jpg)
Absorption
• rapidly absorbed after oral doses• peak plasma concentrations occur
after about 15 to 30 minutes • food reduces the rate but not the
extent of absorption• concomitant antacid use reduces
total availability
![Page 7: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/7.jpg)
Distribution
• high variability of plasma levels between and within studies
• mean plasma levels after single oral doses show a linear relationship with dose over the range of 200-400 mcg
• no accumulation of misoprostol noted in multiple dose studies
• serum protein binding less than 90%, concentration-independent in the therapeutic range
![Page 8: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/8.jpg)
Metabolism
• undergoes rapid de-esterification to its free acid which is clinically active (misoprostol acid)
• misoprostol acid further metabolised by oxidation, primarily in the liver
![Page 9: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/9.jpg)
Excretion• mainly urinary excretion- oral administration of
radiolabeled misoprostol ~ 80% of detected radioactivity appears in urine
• plasma elimination half-life reported to be between 20 and 40 minutes
• misoprostol acid is distributed into breast milk • PK studies in patients with varying degrees of renal
impairment have shown: – approximate doubling of T1/2, Cmax, and AUC compared to
normal controls– no clear correlation between the degree of impairment and
AUC.• no routine dosage adjustment recommended in patients
with renal impairment, but dosage may need to be reduced if the usual dose is not tolerated
• does not affect the hepatic mixed function oxidase (cytochrome P-450) enzyme systems in animals- no known drug interactions
![Page 10: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/10.jpg)
Vaginal Administration
• longer time to peak plasma conc. (70-80min.)
• longer duration of action• greater overall bioavailability (AUC)• large degree of variation in
bioavailability between women• mechanism for direct vagina →
uterus transport of progesterone exists
![Page 11: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/11.jpg)
Sublingual Administration
• tablet dissolves in approx. 20 mins.• shorter time to peak conc. than oral
and vaginal• highest peak concentration• greatest bioavailability• no first pass metabolism in the liver
![Page 12: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/12.jpg)
Pharmacokinetics in Pregnancy
![Page 13: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/13.jpg)
Buccal Route
• similar concentration profile to vaginal administration
• lower bioavailability (~50%)
![Page 14: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/14.jpg)
Rectal Route
• similar concentration profile to vaginal administration
• lower bioavailability (~33%)• onset of action significantly slower
than other routes
![Page 15: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/15.jpg)
Pharmacokinetics in Pregnancy
![Page 16: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/16.jpg)
Clinical Implications
![Page 17: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/17.jpg)
REF:misoprostol.org
![Page 18: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/18.jpg)
Pharmacodynamics
• study of the physiological effects of drugs on the body and the mechanisms of drug action and the relationship between drug concentration and effect
![Page 19: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/19.jpg)
Pharmacodynamics• prostaglandins (PGs) induce myometrial
contraction in the pregnant and non-pregnant uterus ‘triggers of labour’
• sensitivity of uterine muscle to PGs increases with gestation
• PGs lead to cervical ripening and relaxation• naturally occurring PGs rapidly broken down• PGs produced as needed in tissues- not stored• endometrium and myometrium have substantial
PG synthesising capacity
![Page 20: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/20.jpg)
Pharmacodynamics• role in parturition not fully understood• NSAIDs interfere with cyclo-oxegenase (involved
in PG production) and hence prolong labour• EP1 & EP2 receptors contraction promoting,
abundant in the fundus• EP3 & EP4 receptors relaxation promoting, found
in lower uterine segment• varying expression of receptors may be
responsible for differing sensitivity of myometrium throughout gestation and at delivery
![Page 21: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/21.jpg)
Pharmacodynamics
• regulation of PG receptor expression not extensively studied
• progesterone and oestrogen thought to play a role in PG receptor expression
• progesterone antagonist mifepristone increases myometrial response to exogenous prostaglandins
• thought to up-regulate expression of contraction-promoting PG receptors
![Page 22: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/22.jpg)
Physiological Effects
Uterotonic• single oral dose ↑ tonus (for 1-2h)• repeated oral doses→regular contractions• single vaginal dose will produce regular
contractions (sustained plasma conc.)• increased tonus more rapid and more
pronounced with oral/sublingual (8/11 min.) compared with vaginal (20 min.)
• differing durations of action
![Page 23: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/23.jpg)
Physiological Effects
Cervical softening• misoprostol reduces the force
required for cervical dilatation• appears to have an action on
collagen, encouraging disintegration and dissolution
![Page 24: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/24.jpg)
• diarrhoea & abdominal pain• headache• nausea• flatulence• chills/shivering/fever
– Hyperpyrexia (>40°)- doses >600micrograms– Delerium- doses >800micrograms
• uterine rupture• uterine hyperstimulation case reports• amniotic fluid embolism
Adverse Effects
![Page 25: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/25.jpg)
Formulations
• Cytotec® 200 microgram (oral) tab• Isprelor® 25 microgram vaginal tab• Gymiso® 200 microgram (oral) tab• Prostokos® 25 microgram vaginal tab• Vagiprost® 25 microgram vaginal tab • Extemp. 1 microgram/ml oral sol.• Misopess® Controlled-Release Hydrogel
Polymer Vaginal Insert• Licensing issues!!
![Page 26: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/26.jpg)
References1. Aronsson A, Bygdeman M, Gemzell-Danielsson K. Effects of misoprostol on uterine contractility following different routes of
administration. Hum. Reprod. 2004;19(1):81-84.2. Baskett TF. The development of prostaglandins. Best Practice & Research Clinical Obstetrics & Gynaecology 2003;17(5):703-
706.3. Bygdeman M. Pharmacokinetics of prostaglandins. Best Practice & Research Clinical Obstetrics & Gynaecology 2003;17(5):707-
716.4. Chong Y-SMM, Su L-LMM, Arulkumaran SFP. Misoprostol: A Quarter Century of Use, Abuse, and Creative Misuse. Obstetrical &
Gynecological Survey 2004;59(2):128-140.5. Cicinelli EM, De Ziegler DM, Bulletti CM, Matteo MGM, Schonauer LMM, Galantino PM. Direct Transport of Progesterone From
Vagina to Uterus. Obstetrics & Gynecology 2000;95(3):403-406.6. Danielsson KG, Marions L, Rodriguez A, Spur BW, Wong PYK, Bygdeman M. Comparison between oral and vaginal
administration of misoprostol on uterine contractility. Obstetrics & Gynecology 1999;93(2):275.7. Khan R-UM, El-Refaey HMDM, Sharma SM, Sooranna DP, Stafford MMDM. Oral, Rectal, and Vaginal Pharmacokinetics of
Misoprostol. Obstetrics & Gynecology 2004;103(5, Part 1):866-870.8. Meckstroth KRMDMPH, Whitaker AKMD, Bertisch SMD, Goldberg ABMDMPH, Darney PDMDM. Misoprostol Administered by
Epithelial Routes: Drug Absorption and Uterine Response. Obstetrics & Gynecology 2006;108(3, Part 1):582-590.9. Norman JE, Thong KJ, Baird DT. Uterine Contractility and Induction of Abortion in Early Pregnancy by Misoprostol and
Mifepristone. Obstetrical & Gynecological Survey 1992;47(4):282.10. Olson DM. The role of prostaglandins in the initiation of parturition. Best Practice & Research Clinical Obstetrics &
Gynaecology 2003;17(5):717-730.11. Rayburn WF, Powers BL, Plasse TF, Carr D, Di Spirito M. Pharmacokinetics of a Controlled-Release Misoprostol Vaginal Insert
at Term. Journal of the Society for Gynecologic Investigation 2006;13(2):112-117.12. Spitz IM, Bardin CW. Mifepristone (RU 486) -- A Modulator of Progestin and Glucocorticoid Action. N Engl J Med
1993;329(6):404-412.13. Tang OS, Schweer H, Seyberth HW, Lee SWH, Ho PC. Pharmacokinetics of different routes of administration of misoprostol.
Hum. Reprod. 2002;17(2):332-336.14. Tang OS, Gemzell-Danielsson K, Ho PC. Misoprostol: pharmacokinetic profiles, effects on the uterus and side-effects. Int J
Gynaecol Obstet 2007;99 Suppl 2:S160-7.
![Page 27: Misoprostol Pharmacokinetics and Pharmacodynamics Brian Cleary HRB PhD Scholar Health Services Research TCD/CWIUH/RCSI 25 th February 2010.](https://reader034.fdocuments.in/reader034/viewer/2022051618/56649d245503460f949fa6bb/html5/thumbnails/27.jpg)
Thank You!