Animal models of contraception: utility and limitations

Figures & data

Table 1 Comparison of normative reproductive values in species used for contraceptive modeling

Species	Common name	Adult female size (kg)	Median ovarian cycle length (days)	Breeding seasonality	Menstruation	Gestation length (days)
Macaca fascicularis	Cynomolgus macaque	2.5–5.7	29.4	Year-round breeder	Yes	164
Macaca nemestrina	Pig- tailed macaque	4.7–10.9	32	Year-round breeder	Yes	170
Macaca mulatta	Rhesus macaque	5.3	28	Seasonal breeder	Yes	165
Papio anubis	Olive baboon	14.7–17	30	Year-round breeder	Yes; difficult to visualize	170
Mus musculus	Mouse	0.018–0.035	4–5	Year-round laboratory	No	19–21
Rattus norvegicus	Rat	0.25–0.35	4–5	Year-round laboratory	No	21–23
Oryctolagus cuniculus	Rabbit	2–5	Post-copulatory ovulation with sexual receptivity every 4–17 days	Year-round laboratory	No	30–33

Table 2 Comparison of animal models of contraceptive devices

Device	Species	Advantages	Disadvantages
IUD	Baboon	Size permits human-use IUD Transcervical deployment possible Year-round breeder	Expensive
	Macaque	Well characterized	Expensive Hysterotomy placement of IUD Some species are seasonal breeders
	Rodent	Less expensive Well characterized	Filamentous or rod IUD only Hysterotomy placement of IUD
IVR	Macaque	Validated ring for NHP use Well characterized	Ring is smaller than human model More basic vaginal pH than human
	Sheep	Similar body mass to human Less expensive than NHP	Seasonal breeders IUD, NHP Not well characterized
Transdermal delivery systems	Pig	Well characterized in in vitro and in vivo assays Resembles human skin	Expensive
	Macaque	Resembles human skin and reproductive physiology	Expensive
	Rabbit	Less expensive	More heterogeneous drug absorption

Abbreviations: IUD, intrauterine; IVR, intravaginal ring; NHP, nonhuman primate.