ブロモクリプチン
ブロモクリプチンは半合成麦角アルカロイド誘導体であり、**ドパミン作動薬**および**プロラクチン分泌抑制薬**として作用します。 - **犬**: 妊娠中絶または偽妊娠に使用されます（ただし、消化器系の副作用が少ないカベルゴリンの方が好まれることが多いです）。 - **猫**: インスリン要求量を減らすための先端巨大症の補助治療として時折使用されます。 - **馬**: 歴史的に下垂体中葉機能障害（PPID/馬クッシング症候群）または下垂体腺腫に使用されてきましたが、現在はペルゴリドが標準治療です。 > **臨床のポイント**: ブロモクリプチンは犬において顕著な催吐作用を引き起こすことで知られており、これが臨床的な有用性を制限しています。食後投与や制吐薬の併用が必要になる場合があります。
作用機序: Bromocriptine acts primarily by stimulating **postsynaptic dopamine (D2) receptors** in the hypothalamus and anterior pituitary gland. - **Prolactin Inhibition**: Dopamine receptor stimulation → release of prolactin-inhibitory factor (PIF) → direct inhibition of prolactin secretion from the anterior pituitary. - **Acromegaly**: In certain pituitary adenomas, paradoxical suppression of growth hormone (GH) secretion occurs via dopaminergic stimulation. - **CNS Effects**: Activates dopaminergic receptors in the neostriatum of the brain, which can influence motor control and behavior.
動物種別の用量
- Adjunctive treatment of acromegaly · Initial dose of 0.2 mg (total dose) · Unspecified · Unspecified · May reduce insulin requirements.
- Treatment of pituitary adenoma · 0.03-0.09 mg/kg (30-90 micrograms/kg) twice daily PO or SC · PO/SC · twice daily · Its use is limited. Note: ARCI UCGFS Class 2 Drug.
- Treatment of pituitary adenoma · 5 mg (total dose) IM q12h · IM · q12h · To prepare an injectable formulation for IM use from oral dosage forms: Bromocriptine mesylate 70 mg is added to 7 mL of a solution of 80% normal saline and 20% absolute alcohol (v/v). Final concentration is 1% (10 mg/mL).
- Treatment of pseudocyesis (pseudopregnancy) · 10-100 micrograms/kg PO daily in divided doses until lactation ceases · PO · daily in divided doses · until lactation ceases · Vomiting, depression and anorexia are common side effects, usually more problematic than the lactation.
- Treatment of pseudocyesis (pseudopregnancy) · 10-100 micrograms/kg PO twice daily for 10-14 days · PO · twice daily · 10-14 days · Vomiting is very common; reducing dose and administering after meals may help.
- Treatment of pseudocyesis (pseudopregnancy) · 10-50 micrograms/kg PO at least twice a day · PO · at least twice a day
- Pregnancy termination after mismating · 50-100 micrograms/kg PO or IM twice daily for 4-7 days · PO/IM · twice daily · 4-7 days · From day 35-45 after LH surge. Not uniformly effective and may cause vomiting at this dosage (a peripheral acting antiemetic 30 minutes before dose may be helpful).
投与経路
禁忌
- Hypertension
- Pregnancy (in humans, documented teratogenicity not established but contraindicated)
- Nursing/lactating animals (interferes with lactation)
有害事象
- Nausea
- Vomiting (highly prevalent in dogs)
- Sedation
- Fatigue
- Hypotension
- Anorexia
- Depression
- Trembling
- Diarrhea
- Tachycardia
薬物相互作用
- Alcohol · May cause a disulfiram-type reaction
- Butyrophenones (e.g., haloperidol, azaperone) · May increase prolactin concentrations; bromocriptine doses may need to be increased
- Amitriptyline · May increase prolactin concentrations; bromocriptine doses may need to be increased
- Phenothiazines · May increase prolactin concentrations; bromocriptine doses may need to be increased
- Reserpine · May increase prolactin concentrations; bromocriptine doses may need to be increased
- Cyclosporine · May elevate cyclosporine levels
- Erythromycin · May increase bromocriptine levels
- Clarithromycin · May increase bromocriptine levels
- Estrogens or Progestins · May interfere with the effects of bromocriptine
- Ergot Alkaloids · Not recommended; concurrent use has caused severe hypertension and myocardial infarction in humans
- Hypotensive Medications · May cause additive hypotension
- MAO Inhibitors (including amitraz, selegiline) · Avoid use of bromocriptine with these compounds
- Metoclopramide · May cause prolactin release in dogs, negating the effects of bromocriptine for treating pseudopregnancy
モニタリング
- Clinical efficacy (dependent upon the reason for use)
- Blood pressure (especially if patients exhibit clinical signs associated with hypotension)
過量投与
Overdosage may cause **vomiting, severe nausea, and profound hypotension**. - **Clinical Signs in Dogs**: Common findings recorded in decreasing frequency include vomiting, trembling, diarrhea, subdued behavior, and tachycardia. - **Treatment**: Standardized gut removal techniques should be employed when applicable, though emesis often occurs spontaneously. Institute cardiovascular monitoring (blood pressure, heart rate) and provide supportive care as needed.
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