Phenylephrine systemic

Phenylephrine 10-1000 pg/minute Seconds Bradycardia, coronary vasoconstriction, decreased renal perfusion, metabolic acidosis Alpha-1, increased cardiac output (CO), decreased systemic vascular resistance (SVR)... 

The answer is d. (Hardman, p T36J The addition of a vasoconstrictor, such as epinephrine or phenylephrine, to certain short-acting, local anesthetics is a common practice in order to prevent the rapid systemic absorption of the local anesthetics, to prolong the local action, and to decrease the potential systemic reactions. Some local anesthetics cause vasodilation, which allows more compound to escape the tissue and enter the blood. Procaine is an ester-type local anesthetic with a short duration of action due to rather rapid biotransformation in the plasma by cholinesterases. The duration of action of the drug during infiltration anesthesia is greatly increased by the addition of epinephrine, which reduces the vasodilation caused by procaine. 

In brain slices, even though no anesthesia is present, there is a reduction in both noradrenergic and other inputs to these cells (e.g., from sensory systems) thus most of these neurons become silent. Consistent with this interpretation is the fact that all presumed serotonergic neurons we have tested in the brain slice are uniformly activated by norepinephrine or the < ragonist phenylephrine, applied either iontophoretically or in the perfusion medium (51). Similarly, in... 

Rhinocort Aqua and Nasonex are preparations containing topical nasal corticosteroids (budesonide and mometasone furoate respectively). Otrivine contains a nasal decongestant (xylometazoline) and Sudafed is a systemic preparation containing a nasal decongestant (phenylephrine). Molcer is a preparation for ear-wax removal and which contains docusate sodium. Emadine contains an antihistamine (emedastine) and is presented as eye drops. 

Q71 Cold preparations containing phenylephrine intended for systemic administration should be avoided in patients with ... 

Phenylephrine is a nasal decongestant that mimics the sympathetic system, thereby increasing the heart rate and blood pressure. It may aggravate conditions such as diabetes, hypertension and glaucoma. Patients with hypertension, ischaemic heart disease, hyperthyroidism, diabetes and glaucoma are therefore given topical nasal sympathomimetics rather than systemic sympathomimetics. Both topical and systemic sympathomimetics are contraindicated in patients taking monoamine oxidase inhibitors, because concurrent administration of the two products may lead to a hypertensive crisis. 

Triprolidine is an antihistamine. Phenylpropranolamine, pseudoephedrine, phenylephrine and oxymetazoline are nasal decongestants. Nasal decongestants administered systemically are often available in combination with an antihistamine. 

Manage rebound congestion by stopping phenylephrine one nostril at a time, substitute systemic decongestant and/or inhaled steroid... 

Mecfianism of Action Phenylephrine HCl is an alpha-receptor sympathetic agonist used in local ocular disorders because of its vasoconstrictor and mydriatic action. It exhibits rapid and moderately prolonged action, and it produces little rebound vasodilatation. Systemic side effects are uncommon. Therapeutic Effect Vasoconstriction and pupil dilation. 

Combining agonists with some local anesthetics greatly prolongs the duration of infiltration nerve block the total dose of local anesthetic (and the probability of toxicity) can therefore be reduced. Epinephrine, 1 200,000, is the favored agent for this application, but norepinephrine, phenylephrine, and other agonists have also been used. Systemic effects on the heart and peripheral vasculature may occur even with local drug administration but are usually minimal. 

A combination of phentolamine with the nonspecific smooth muscle relaxant papaverine, when injected directly into the penis, may cause erections in men with sexual dysfunction. Long-term administration may result in fibrotic reactions. Systemic absorption may lead to orthostatic hypotension priapism may require direct treatment with an -adrenoceptor agonist such as phenylephrine. Alternative therapies for erectile dysfunction include prostaglandins (see Chapter 18), sildenafil and other cGMP phosphodiesterase inhibitors (see Chapter 12), and apomorphine. 

The total surface area of the nasal cavity is about 150 cm2, with the area available for absorption enhanced by the convolutions of the turbinates and the presence of microvilli on the surface of the ciliated and unciliated cells of the respiratory epithelium. The arterial supply of the nose is particularly rich in the respiratory epithelium where the Kiesselbach s plexus lies, an area that is rich in numerous capillary loops. The nasal blood flow has been shown to be sensitive to the action of a variety of inhaled compounds, both locally or systemically acting. Clonidine has been shown to decrease the blood flow whereas histamine and phenylephrine have been shown to induce the converse effect. Such direct changes to blood flow are important in determining the rate and extent of drug absorption from the nasal cavity. 

Phenylephrine (Neo-Synephrine, others). Like methoxamine, phenylephrine can be administered systemically to treat hypotension, and phenylephrine can also be used to terminate certain episodes of supraventricular tachycardia. In addition, phenylephrine is administered topically to treat nasal congestion and is found in many over-the-counter spray decongestants. 

Central nervous system toxicity is rarely observed with catecholamines or drugs such as phenylephrine. In moderate doses, amphetamines commonly cause restlessness, tremor, insomnia, and anxiety in high doses, a paranoid state may be induced. Cocaine may precipitate convulsions, cerebral hemorrhage, arrhythmias, or myocardial infarction. Therapy is discussed in Chapter 59 Management of the Poisoned Patient. 

The anesthetic effect of the agents with short and intermediate durations of action can be prolonged by increasing the dose or by adding a vasoconstrictor agent (eg, epinephrine or phenylephrine). The vasoconstrictor retards the removal of drug from the injection site. In addition, it decreases the blood level and hence the probability of central nervous system toxicity. 

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