indication

Indicated as adjunctive treatment to levodopa/carbidopa in the management of the signs and symptoms of Parkinson's disease. It was withdrawn from the US and Canadian markets in 2007 due to an increased risk of cardiac valvulopathy.

pharmacology

Pergolide stimulates centrally-located dopaminergic receptors resulting in a number of pharmacologic effects. Five dopamine receptor types from two dopaminergic subfamilies have been identified. The dopaminergic D1 receptor subfamily consists of D₁ and D₅ subreceptors and are associated with dyskinesias. The dopaminergic D2 receptor subfamily consists of D₂, D₃ and D₄ subreceptors and has been associated with improvement of symptoms of movement disorders. Thus, agonist activity specific for D2 subfamily receptors, primarily D₂ and D₃ receptor subtypes, are the primary targets of dopaminergic antiparkinsonian agents. It is thought that postsynaptic D2 stimulation is primarily responsible for the antiparkinsonian effect of dopamine agonists, while presynaptic D2 stimulation confers neuroprotective effects. This semisynthetic ergot derivative exhibits potent agonist activity on dopamine D₂- and D₃-receptors. It also exhibits agonist activity on dopamine D₄, D₁, and D₅, 5-hydroxytryptamine (5-HT)_1A, 5-HT_1B, 5-HT_1D, 5-HT_2A, 5-HT_2B, 5-HT_2C, α_2A-, α_2B-, α_2C-, α_1A-, α_1B-, and α_1D-adrenergic receptors. Parkinsonian Syndrome manifests when approximately 80% of dopaminergic activity in the nigrostriatal pathway of the brain is lost. As this striatum is involved in modulating the intensity of coordinated muscle activity (e.g. movement, balance, walking), loss of activity may result in dystonia (acute muscle contraction), Parkinsonism (including symptoms of bradykinesia, tremor, rigidity, and flattened affect), akathesia (inner restlessness), tardive dyskinesia (involuntary muscle movements usually associated with long-term loss of dopaminergic activity), and neuroleptic malignant syndrome, which manifests when complete blockage of nigrostriatal dopamine occurs. High dopaminergic activity in the mesolimbic pathway of the brain causes hallucinations and delusions; these side effects of dopamine agonists are manifestations seen in patients with schizophrenia who have overractivity in this area of the brain. The hallucinogenic side effects of dopamine agonists may also be due to 5-HT_2A agonism. The tuberoinfundibular pathway of the brain originates in the hypothalamus and terminates in the pituitary gland. In this pathway, dopamine inhibits lactotrophs in anterior pituitary from secreting prolactin. Increased dopaminergic activity in the tuberoinfundibular pathway inhibits prolactin secretion. Pergolide also causes transient increases in somatotropin (growth hormone) secretion and decreases in luteinizing hormone (LH) concentrations.

mechanism of action

The dopamine D₂ receptor is a 7-transmembrane G-protein coupled receptor associated with G_i proteins. In lactotrophs, stimulation of dopamine D₂ receptor causes inhibition of adenylyl cyclase, which decreases intracellular cAMP concentrations and blocks IP3-dependent release of Ca²⁺ from intracellular stores. Decreases in intracellular calcium levels may also be brought about via inhibition of calcium influx through voltage-gated calcium channels, rather than via inhibition of adenylyl cyclase. Additionally, receptor activation blocks phosphorylation of p42/p44 MAPK and decreases MAPK/ERK kinase phosphorylation. Inhibition of MAPK appears to be mediated by c-Raf and B-Raf-dependent inhibition of MAPK/ERK kinase. Dopamine-stimulated growth hormone release from the pituitary gland is mediated by a decrease in intracellular calcium influx through voltage-gated calcium channels rather than via adenylyl cyclase inhibition. Stimulation of dopamine D₂ receptors in the nigrostriatal pathway leads to improvements in coordinated muscle activity in those with movement disorders.

toxicity

Oral, rat LD₅₀: 15 mg/kg. Symptoms of overdose include nausea, vomiting, convulsions, decreased blood pressure, and CNS stimulation.

biotransformation

Extensively hepatic.

absorption

Significant amount may be absorbed (evidence on bioavailability still lacking).

half life

27 hours

route of elimination

The major route of excretion is the kidney.

drug interactions

Tamoxifen: Pergolide may decrease the therapeutic effect of Tamoxifen by decreasing the production of active metabolites. Concomitant therapy should be avoided.

Tamsulosin: Pergolide, a CYP2D6 inhibitor, may decrease the metabolism and clearance of Tamsulosin, a CYP2D6 substrate. Monitor for changes in therapeutic/adverse effects of Tamsulosin if Pergolide is initiated, discontinued, or dose changed.

Telithromycin: Telithromycin may reduce clearance of Pergolide. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Pergolide if Telithromycin is initiated, discontinued or dose changed.

Thiothixene: Thiothixene may antaonize the effects of the anti-Parkinsonian agent, Pergolide. Consider alternate therapy or monitor for decreased effects of both agents.

Tipranavir: Tipranavir may increase the plasma concentration of Pergolide. Concomitant therapy should be avoided.

Tolterodine: Peroglide may decrease the metabolism and clearance of Tolterodine. Monitor for adverse/toxic effects of Tolterodine.

Tramadol: Pergolide may decrease the effect of Tramadol by decreasing active metabolite production. Increased risk of serotonin syndrome. Monitor for Tramadol efficacy and symptoms of serotonin syndrome.

Tranylcypromine: Increased risk of serotonin syndrome. Use caution during concomitant therapy and monitor for symptoms of serotonin syndrome.

Trazodone: Increased risk of serotonin syndrome. Monitor for symptoms of serotonin syndrome.

Trimipramine: Increased risk of serotonin syndrome. Pergolide, a strong CYP2D6 inhibitor, may also decrease the metabolism and clearance of Trimipramine, a CYP2D6 substrate. Monitor for symptoms of serotonin syndrome and changes in Trimipramine therapeutic and adverse effects if Pergolide is initiated, discontinued or dose changed.

Venlafaxine: Increased risk of serotonin syndrome. Monitor for symptoms of serotonin syndrome.

Voriconazole: Voriconazole may increase the serum concentration of pergolide likely by decreasing its metabolism. Concomitant therapy is contraindicated.

Ziprasidone: The atypical antipsychotic, ziprasidone, may antagonize the effect of the dopamine agonist, pergolide. Consider alternate therapy or monitor for worsening of movement disorder.

Zolmitriptan: Concomitant use of the serotonin 5-HT1D receptor agonist, zolmitriptan, and the ergot derivative, pergolide, may result in additive vasoconstrictive effects. Concomitant use within 24 hours is contraindicated.

Zuclopenthixol: Antagonism may occur between zuclopenthixol, a dopamine D2 receptor antagonist, and pergolide, a dopamine agonist. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of both agents if concurrent therapy is initiated, discontinued or dose(s) changed. Pergolide, a strong CYP2D6 inhibitor, may increase the serum concentration of zuclopenthixol by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of zuclopenthixol if pergolide is initiated, discontinued or dose changed.