Drug Delivey for contraception

What do progestogens do?

They are steroid hormones that bind to and activate the progesterone receptors.

name the two progestogens?

Progesterone (natural)

Progestins (synthetic)

What are the three different types of contraceptive pills? (regimens)

Monophasic - same amount of oestrogen and progestogen throughout all 21 days

triphasic - 21 day pills with varying quantities of oestrogen and progestogen

Everyday - 28 day pills, 21 contain oestrogen and progestogen rest are “empty”

What are the advantages of the combined contraceptive pill?

Reliable, easily reversible, reduced risk of aneamia, reduced risk of endometrial and ovarian cancer, relief of premenstrual symptoms

What are the disadvantages of the combined contraceptive pill?

91% efficacy with less careful use

no protection against STIs

unsuitable for smokers aged 35 and over

What is the differences with progestogen only pill?

Not contraindicated by breastfeeding as it does no inhibit lactation

no evidence of increase risk of hypertension

if the pop fails it may have possible increased risk of ectopic pregnancy rate

Why is there a need for alternatives?

Compliace, e.g pills may be missed

Accessibility, some patients may not be able to travel to pharmacy to collect more pills

What is the vaginal ring?

Nuva ring - combined contraceptive pill compose of ethylene, vinyl acetate in 2 um ring which releases:

120 micrograms progestogen

15 micrograms oestrogen

reservoir type

How does the vaginal ring work?

Ovulation is inhibited and cervical mucus is altered so that sperm cannot penetrate it and endometrium is rendered unfavorable for implantation

Inserted first day of period and remains for three weeks

removed for one week and withdrawal bleed occurs

Stored in fridge but can stay out for up tot 4 months after dispensing

What is the contraceptive patch? and how is it used?

Combined method

Day 1 - patch 1 is applied

day 8 - patch 1 removed and patch 2 applied

Day 15 - patch 2 removed patch 3 applied

day 22 - patch 3 removed and withdrwal bleed until day 28

How does the contraceptive path work?

Ovulation is inhibited and cervical music is altered so that it is impenetrable to sperm

Patches can either be a reservoir or matrix

What design considerations do we need to have with contraceptive patches?

Adhesive - needs to be medically approved and tested, non irritating, hypoallergenic, elastic movement easily removed

packing - impermeable, reservoir must not leak

reservoir - can be a solution of drug or suspension

membrane - permeable so drug can be released into skin

What is the contraceptive implant?

Ovulation is inhibited and cervical mucus altered so it is impermeable to sperm.

Rod contains 68mg etornogestrel

What are the advantages of the contraceptive implant?

No user action needed

Highly effective

reversible

What are the disadvantages of the implant?

Requires trained professionals to insert and remove

can result in irregular bleeding or spotting

side effects include acne and headaches

What’s the difference between matrix and reservoir contraceptive patches?

Matrix - Drug is uniformly distributed though out polymer matrix rate of release in initially more rapid and slows down as conc. of drug near polymer decreases

Reservoir - A rate limiting membrane controls release of drug from core reservoir, devices typically display more contrast release rates

What rule does release from reservoir follow?

It follows Ficks law of diffusion

What are sink conditions?

When the drug is at the saturated conc. in the reservoir, the vol of bodily fluid into which the drug partitions is large enough to prevent the conc. of the drug in the bodily fluid exceeding 10% of that the donor

What rule do drug release kinetics in matrix devices follow?

Higuchi equation