<s>[INST] context: Spermicides
"Spermicides are contraceptive chemical agents. They comprise,of a chemical capable of destroying sperm, incorporated into an inert base. The commonly used spermicidal agents contain nonionic surfactants which alter sperm surface membrane permeability, causing osmotic changes resulting in killing of sperm. Most of the spermicides contain nonoxynol-9 which is the best for this purpose." Ref. Current Concepts in Contraception and Women Health by Jaypee Publication p 32

Spermicidal agents kill the sperms before it enters to the cervical canal. They are available as foam tablets, soluble pessaries, creams, jellies, or as films.
Contents are:
Nonoxynol - 9 (N - 9)
Menfegol
Benzalknonium chloride.
Octoxynol
Enzyme inhibiting agents


Failure rate is 20-25 WY 100 woman years when used alone. When used in conjunction with a mechanical barrier, they give a reliable contraceptive effect.

Note:

Recent evidences indicate spermicides are not effective in preventing cervical gonorrhoea, Chlamydia or HIV infection. In addition, frequent use of spermicides containing N-9 has been associated with an increased risk of HIV transmission.                                           
Advantage 24 is a new contraceptive gel which contains nonoxynol. [/INST] question: Spermicidal agents are:a) Nonoxynolb) Menfegolc) Progestasertd) Mirena | options: A: ac B: a C: ab D: bc | answer: C </s>