Dopamine contraindications

Educate patient about safety and efficacy of dopamine agonists. Make sure that the patient does not have any contraindications or allergies to drug therapies. 

Apomorphine is a nonergot dopamine agonist given as a subcutaneous rescue injection. For patients with advanced PD with intermittent off episodes despite optimized therapy, subcutaneous apomorphine triggers an on response within 20 minutes, and duration of effect is up to 100 minutes. Most patients require 0.06 mg/kg. Prior to injection, patients should be premedicated with the antiemetic trimethobenzamide. It is contraindicated with the serotonin-3-receptor blockers (e.g., ondansetron). 

The triazolopyridine trazodone does not have an appreciable effect on the re-uptake of the neurotrans-mittors dopamine or noradrenaline. It is a weak inhibitor of serotonin re-uptake but is a potent antagonist of the serotonin 5-HT2 receptor. Clinical experience has shown unpredictable efficacy. Trazodone has little antimuscarinic activity and has little if any action on cardiac conduction. Like mianserin it can therefore safely be used in patients for which anticholinergics are contraindicated and there are no absolute contraindications for patients with concomitant diseases of the cardiovascular system. 

The most troublesome untoward effects of treatment with reserpine involve the CNS. Sedation and depression are the most common, although nightmares and thoughts of suicide also occur. Reserpine treatment, therefore, is contraindicated in patients with a history of severe depression. The occasional report of re-serpine-induced extrapyramidal symptoms, which are similar to those seen in patients with Parkinson s disease, is believed to be a result of dopamine depletion from neurons in the CNS. 

B. Apomorphine is an older drug with dopamine receptor agonist properties. It acts both centrally and peripherally. It is not contraindicated in cases of BPH but rather may be the drug of choice in this instance. 

Dopamine agonists are contraindicated in patients with a history of psychotic illness or recent myocardial infarction, or with active peptic ulceration. The ergot-derived agonists are best avoided in patients with peripheral vascular disease. 

Dopamine agonists were used in the past to prevent breast engorgement when breast-feeding was not desired. Their use for this purpose has been discouraged because of toxicity (see Toxicity Contraindications). 

Interactions The vitamin pyridoxine (B6) increases the peripheral breakdown of levodopa and diminishes its effectiveness (Figure 8.6). Concomitant administration of levodopa and monoamine oxidase (MAO) inhibitors, such as phenelzine (see p. 124), can produce a hypertensive crisis caused by enhanced catecholamine production therefore, caution is required when they are used simultaneously. In many psychotic patients, levodopa exacerbates symptoms, possibly through the buildup of central amines. In patients with glaucoma, the drug can cause an increase in intraocular pressure. Cardiac patients should be carefully monitored because of the possible development of cardiac arrhythmias. Antipsychotic drugs are contraindicated in parkinsonian patients, since these block dopamine receptors and produce a parkinsonian syndrome themselves. 

Inhibitors of monoamine oxidase A (thy-meretics). Moclobemide is the only representative of this group. It produces a reversible inhibition of MAOa, which is responsible for inactivation of the amines norepinephrine, dopamine, and serotonin (A). Enzyme inhibition results in an increased concentration of these neurotransmitters in the synaptic cleft. Moclobemide is less effective as an antidepressant than as a psychomotor stimulant. It is indicated only in depressions with extreme psychomotor slowing and is contraindicated in patients at risk of suicide. 

Pyridoxine (vitamin Bb, in the form of pyridoxal phosphate) is a cofactor in the formation of dopamine from L-DOPA. It used to be thought that pyridoxine supplements would be helpful to treat Parkinson s disease. The opposite was found vitamin B6 apparently also enhances L-DOPA conversion to dopamine in other areas of the body. This means that less of the administered L-DOPA is available for entry into tlie brain. Therefore, Be treatment presently is contraindicated in Parkinson s disease. 

Agitation, which may occur in patients with dementia, can be treated with anti-psycho tics agents, mood stabilizing anticonvulsants, trazadone and anxiolytics (Doody et al., 2001). The atypical anti-psychotic medications are the treatment of choice for psychotic symptoms, such as hallucinations or delusions, particularly in those with Parkinsonism in whom dopamine receptor blockage is contraindicated due to the potential to worsen motor symptoms. In these patients, clozapine, which may reduce tremor in addition to its anti-psychotic effects, is particularly effective. However, rare cases of agranulocystosis necessitate weekly blood counts, and so limit its utility. Que-tiapine may be the next agent of choice because it appears to have fewer adverse motor effects than the other medications... 

Bupropion is another second-line agent, particularly for patients who are wary of the SSRIs negative impact on sexual dysfunction. Because it appears to relieve depression through a completely different mechanism than SSRIs, enhancing norepinephrine or dopamine, it is often administered to patients who fail SSRIs or exhibit a partial response. The most common side effects encountered with bupropion are insomnia, jitteriness, and nausea. Bupropion is contraindicated in patients with a history of seizures or eating disorders. 

Serious ingestions require cardiac monitoring in an intensive-care setting. Hypotension may be resistant to dopamine and dobutamine. Norepinephrine can also be used. Bradycardia can be treated with atropine and a temporary pacemaker as needed. Digoxin-specific FAB antibody fragments have been used with some success for cardiac conduction abnormalities after a yew exposure. If no contraindication, lido-caine, amiodarone, or procainamide may be used for ventricular dysrhythmias. 

Bupropion (100 mg p.o. b.i.d.) is indicated in the treatment of depression. It is reserved for patients who cannot tolerate or have not responded to other medications. Bupropion does not alter the uptake of serotonin, has an equivocal effect on the uptake of norepinephrine, but blocks the uptake of dopamine. Bupropion has no affinity for alpha-1 and alpha-2-adrenergic receptors, H,-histamine receptors, muscarinic cholinergic receptors, or D2-dopaminergic receptors. It does not cause sedation or orthostatic hypotension. However, because it is structurally related to amphetamine, it may cause insomnia, agitation, and anxiety shortly after initiation of therapy. Bupropion lowers the seizure threshold and hence is contraindicated in patients with a history of seizure disorder (see also Tables 5 through 7). 

Metoclopramide is contraindicated in the presence of GI hemorrhage, mechanical obstruction, or perforation. Because it is a dopamine-receptor-blocking agent, it causes extrapyramidal reactions such as dystonia and parkinsonism. 

Dopamine-receptor antagonists having antipsychotic properties, such as phenothiazine, butyrophenone, and thioxanthene derivatives, and Gl-stimulant drugs, such as metoclopramide, are contraindicated with pergolide. The... 

Remember that levodopa is a precursor of norepinephrine and epinephrine as well as dopamine and that norepinephrine and epinephrine are metabolized primarily by monoamine oxidase type A. In the presence of nonselective inhibitors of monoamine oxidases, levodopa may cause a hypertensive crisis. Though not contraindicated in Parkinson s disease, tricyclic antidepressants may interfere with the effectiveness of levodopa. The answer is (D). 

Because of its weak MAO-inhibitory properties, the manufacturers of linezolid contraindicate its use with sympathomimetics (such as adrenergic bronchodilators, phenylpropanolamine, pseudoephedrine, adrenaline (epinephrine), noradrenaline (norepinephrine), dopamine and dobutamine) unless facilities for close observation and blood pressure monitoring are available. In one study the use of linezolid with phenylpropanolamine or pseudoephedrine resulted in additive hypertensive effects. 

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