drugs Flashcards
progestogens
most frequently used method
in male animals = prevents sexually related behaviour eg spraying
contraceptive effects of progestogens
negative feedback effect on hypothalamus + pituitary
-> prevents stimulation of follicle growth and ovulation (continuous high conc suppress FSH+ LH production)
sufficient estrogen production may continue to stimulate some follicle growth and estradiol production
-> oestrus behaviour may still occur
impede movement of sperm and eggs to site of fertilisation
interfere with implantation
side effects of progestogens
depend on type, dose, duration and age of animal
less if given in anestrus and small doseas
increase appetite, weight gain, lethargy, alopecia, adrenocortical suppression, acromegaly symptoms
uterine pathology - CEH, pyometra
mammary gland neoplasia
medroxyprogesterone acetate
long lasting injection
2mg/kg SC or 5mg PO for 21d max
return to estrus in 2-9 months
most adrogenic and immunosuppresivem
melengestrol acetate
temporary estrus suppression (can be used with GnRH agonist)
2.2mg/kg PO for 8 d early in proestrus
2-4w administration during anestrus
antiadrogenic, antiestrogenic, cortisol agent
proligestone
estrus suppression
10-30mg/kg SC repeated at 3+7 month post 1st injection
return to estrus in 9-12 moths (up to 2-3years)
antigonadotropic, less progestognenic than other
contraception GnRH (agonist)
suppression of GnRH -> suppression of repro steroid hormones and so decrease sexual behaviour and fertility etc
worry over effect on non-target tissue
bind to GnRH receptors in pituitary and cause down regulation -> continuous administration -> complete suppression
pros = good for male and female suppression estrus behaviour reversbiel
conc
= initial inducement of estrus and increase in temp (due to FSH and LH)
slow onset and variable duration injection or SC implant
deslorelin
implant for male (females and cats too)
4.7mg for 6m, 9.4mg for 12 m
dose dependent time for return to feritlity
nafarelin
18.5mg SC implant
-> 2ug/kg/day SC
last 8-11 mo after removal of implant im bitches and 3 year in cats
GnRH antagonist
block GnRH receptors on pituitary cells without causing initial stimautlion of sexual behaviour
expensive - peptide on non-peptide molecules
generations: detirelix, acilin, degarelix, cetrorelix
pros = suppression for short time, suppresses estrus behaviour, reversible
non-peptides = cheaper and can be given PO, effect starts quicklyy
cons
= frequent applciation
reversible
no depo or long acting formaultions
first gen can cause histamine reaction in dogs
not in early pregnancy (LH)
2nd gen = luteal suppression + preg termination
3rd gen= preg termination and progesterone, decrease without side effects
zinc gluconate
esterilsol
direct injection in to testes (need sedation and analgesia)a
if given to prepubertal males then permanent sterilisatin
destroys sperm cells, followed y shrinking and scarring of epididymis and seminiferous tubules
in adult males take sup to 6 weeks to achieve sterilisation
vinycyclohexane diepoxide (VCD)
for females
eliminates primordial follicles by accelerating nuatral process of follicular atresia -> ovarian failrure
no estrus behaviour and permanent sterility
pros = permanent, low cost, convenient, easy, no need for surgeery
cons = irreversible side effects may need surgery
immunocontraception
humour and cell-median immune response against specific proteins or tissues involved in reproduction
problems = lack of antigenicity of repo specific proteins
desire to not block function of those proteins in non-target tissues
inflamm response associate with immune reaction that may damaged surround tissue
potential immunogenicity = GnRH, zona pellcudia, LH, FSH, egg and sper, specific proteins
melatonin
for cats
PO for 30-35d - implant better
short tem suppression -> 2-4 months, reversible, caution - initial induction of esters 12-18mg
izoquinoline derivatives
not safe in dogs - GI signs, anorexia, possible birth of live, CEH, pyometra
15-20d of pregnancy interfere with implantation
progesterone blockers
synthetic steroids that act as competitive inhibitors of progesteroen
mitepristone = too exepsnvei
aglepristone = up to 45d of pregnancy, 10mg/kg SC 2x in 24h, 0-25d for prevention, 26-45d = induces abortion/aresopriotn within 7d
US after 20d if earl in pregnancy or 8d if middle of pregnancy
mild, if any side effects - discharge, shortened interesutrous period, prolactin and mamary gland enlargement
prostaglandins in F2a
luteolytic and utertonic action
natural = dinoprosvt. synthetic = cloprostenol
dinoprosvt
= dose dependent side effects: hyper salivation, decreased HR, vomiting, that stops 1 h after admin, gradually increase dosage
cloprostenol
= more potent but decreased side effects, from 200-120d
progesterone synthesis blockers
competitive inhibition
possible interference with steroidogenesis from adrenal
dopamine agonist
effect D2 receptors -> decrease prolactin secretion -> decrease progesterone
decrease prolactin -> luteolytiss
bromocriptine = strong effect,ataxia and omiting
cabergoline = more efficient in smaller dose, milder side effects, movre peicfi cD2 receptors agonist and eodesn’t cross BBB as easy, efficient after 30d,
combined therapy
D2 agonists and PGF2a
-> 100% effective from day 25+, less side effects, don’t have to give everyday , cabergoline PO
aglespristone and PGF
misopristol = synthetic analogue of PGE, intravaginal - causes cervical dilation
combo with anglepirston = abortion in shorter duration (6d)
oestrogens
banned in EU s
strong side effects
give 6-10 d post copulation
- extends the time embryo spends in oviduct and prevent migration to uterus -> embryo degeneration and abortion
antiestogens and amoxifen
selective inhibitor of estrogneic receptors with strong antiestrogenic effect on mammal gland
estrogenic effect in bitch
100% effective from 15th day of destroys
side effects
glucocorticoids
dex
effective from mid pregnancy
-> if before 40d no fetoal expulsion
therapy continued until death of all confirmed
side effected = anorexia, PUPD, stop after a few days, transit adrenal suppress
steroid levels bam to normal within a week of sotopping
mibolerone
at least 30 d before expected estrus
for up to 5 yera
next cycle in 70d
hepatotoxic effect in bedingotons
GnRH toxin conjugates
GnRH coupled to a toxin or protein sntehssi inhibtors
bind to GnRH redeptors in target cell, internalisation of complex + release of toxin-> cell death so ermine sterility
little or no off target toxicity
