Pharmacology 2 Flashcards
advantages to intrauterine drug administration
- high concentrations at the endometrium
- lower total doses of antibiotics can be used
- decreased cost
- decreased risk of adverse systemic effects
disadvantages of intrauterine drug administration
- only the endometrium is consistently treated
- systemic absorption can occur to varying degrees
- difficult to perform in small animals
- cannot be used in pregnant animals (placentitis)
- local factors may effect efficacy
- can be irritating to the uterine lining
advantages of systemic drug administration
- uterine concentrations typically equal to or greater than systemic concentrations
- treats the entire uterus and repro tract
- decreased risk for local adverse effects
- owner can perform
disadvantages of systemic drug administration for uterine dz
- cost
- risk for systemic toxicity
- relies on client compliance
advantages for systemic drug administration in mammary dz
- more even distribution throughout the udder
- treats septicemia (toxic mastitis)
advantages in intramammary drug admin
- high concentrations at the site of infection
- long acting formulations can result in prolonged drug concentrations at this site
- less systemic absorption
- many approved products for cattle
- minimal metabolism in the udder
disadvantages of of systemic drug admin for mammary dz
- barriers to drug penetration in the udder
- difficult to maintain therapeutic concentrations
- IV admin may be necessary to maintain high concentrations
- residues may be present in all 4 teats
- residues may persist longer if milk production is decreased
disadvantages of intramammary drug administration
- possible irritation of mammary tissue
- risk for contamination when infusing
- residues may persist longer if milk production is decreased
- residues may be present in all 4 teats
- drugs may affect local immune system
pergolide
Mechanism of action: Dopamine agonist
Effects on pregnancy: Prolonged gestation (up to 1 year); agalactia/dysgalactia; poor quality colostrum; retained placenta.
Recommendations: Stop treatment 2 weeks prior to expected foaling date (4 weeks if they have had problems in the past); restart treatment 4 weeks after foaling. If unable to stop treatment be
prepared to tube foal with colostrum and/or get nurse mare.
NSAIDS
Mechanism of action: Inhibition of prostaglandin production via inhibition of cyclooxygenase
enzymes.
Effects on pregnancy: Blocking PGF2α may result in delayed induction of parturition. NSAIDs have also been implicated in development of the fetal and neonatal kidney and is partially
responsible for maintaining a patent fetal ductus arteriosus.
Recommendations: Choose alternative pain medications. If unable to find alternative
medication, use the lowest dose and the shortest duration of dosing possible.
Clenbuterol
Mechanism of action: β2 adrenergic agonist
Effects on pregnancy: Stimulation of β2 receptors causes relaxation of the uterine musculature. May prolong gestation.
Recommendations: Can be used specifically for this purpose to prevent premature labor. If being used for bronchodilation, may need to stop shortly before expected due date (can switch to
inhaled albuterol if needed).
Nifedipine
Mechanism of action: Calcium channel blockers
Effects on pregnancy: Blockage of L-type voltage gated calcium channels in the uterus causes relaxation of the uterine musculature. May prolong gestation.
Recommendations: Can be used specifically for this purpose to prevent premature labor. If being used for hypertension, may need to stop shortly before expected due date.
Glucocorticoids
Mechanism of action: Transactivation of anti-inflammatory genes and transrepression of proinflammatory genes
Effects on pregnancy: Enhancements of the immunosuppressive effect of the decidua, alterations in placental growth factor levels, decreased serum progesterone and 17β-estradiol levels, and the reduced frequency of uterine macrophages and uNK cells. May result in early termination of the pregnancy.
Recommendations: Do not use unless attempting to terminate a pregnancy. May be safer in horses than other species.
misoprostal
Mechanism of action: Synthetic prostaglandin E analogue
Effects on pregnancy: Softens the cervix; causes the uterus to contract; induces labor. Likely to result in early termination of the pregnancy.
Recommendations: Do not use unless attempting to terminate a pregnancy. FDA pregnancy category X. Also teratogenic in humans.
Domperidone
Mechanism of action: Dopamine type 2 (D2) receptor antagonist
Effects on lactation: Increases prolactin secretion; stimulates lactation.
Recommendations: Labeled for use in the treatment of fescue toxicity induced agalactia in mares; may also be useful in counteracting effects of pergolide.
