Phenylephrine Atropine

Jimenez-Jimenez FJ +, Rev Neurol 43(10), 603 (with atropine phenylephrine)... 

Acebutorol, arotinolol, atropine, bupivacaine, clorprenaline, denopamine, eperisone, epinastine, etirefline, fenoterol, homatropine, ketamine, metanephrine, metoprolol, mexiletine, nicardipine, oxyphencyclimine, phenylephrine, pindolol, primaquine, promethazine, sulpiride, ter-butaline, tolperizone, trihexyphenidyl, trimebutine, trimetoquinol, trimipramine, verapamil 81... 

B. Phenylephrine is an aj-selective agonist. It causes an increase in peripheral vascular resistance. The major cardiovascular response to this drug is a rise in blood pressure associated with reflex bradycardia. The slowing of the heart rate is blocked by atropine. 

Q4 Yes. Rob has used both atropine and phenylephrine this afternoon. Muscarinic antagonists such as atropine, tropicamide and cyclopentolate cause dilation of the pupils. The a-adrenoceptor agonists, such as phenylephrine, also produce my driasis. Mydriasis may cause acute closed-angle glaucoma in some patients. It is unlikely that a very small amount of cocaine in the eye would cause problems, but in cocaine overdose pupils become widely dilated. This is due to blockade of uptake 1, a process normally involved in terminating the effects of noradrenaline. In the presence of cocaine the effects of sympathetic stimulation on the eye would be prolonged and the pupil would dilate. Morphine causes constriction of the pupils via opiate receptors. 

SYMPATHOMIMETICS ANTIMUSCARINICS -ATROPINE Reports of hypertension when atropine was given to patients receiving 10% phenylephrine eye drops during eye surgery Atropine abolishes the cholinergic response to phenylephrine-induced vasoconstriction Use a lower concentration of phenylephrine... 

Patients taking certain systemic medications are also more sensitive to the pressor effects of phenylephrine. In individuals taking atropine, the pressor effect of phenylephrine is augmented, and tachycardia can occur. Tricyclic antidepressants and monoamine oxidase (MAO) inhibitors also potentiate the cardiovascular effects of topical phenylephrine. The concomitant use of phenylephrine is contraindicated with these agents, even up to 21 days after cessation of MAO inhibitor therapy. Similarly, patients taking reserpine, guanethidine, or methyldopa are at increased risk for adverse pressor effects from topical phenylephrine because of denervation hypersensitivity accompanying the chemical sympathectomy. 

Concomitant use of topical phenylephrine is discouraged in atropinized patients, because tachycardia and hypertension can occur. 

Mydriatics/anticholinergics Phenylephrine, atropine, scopolamine, homatropine, tropicamide Topical anesthetics Proparacaine Glaucoma... 

For their peripheral actions, atropine, horn atropine and cycl open to late are used in opht/io/moiogy to dilate the pupil and to paralyse ocular accommodation. Patients should be warned of a transient, but unpleasant stinging sensation, and that they cannot read or drive (at least without dark glasses) for at least 3 hours.Tropicamide is the shortest acting of the mydriatics. If it is desired to dilate the pupil and to spare accommodation.a sympathomimetic, e.g, phenylephrine, is useful. 

Phenylephrine is a sympathomimetic aj adrenoceptor agonist capable of producing mydriasis in some species by iris dilator muscle contraction. In the horse, topical application of a 10% solution has been shown to have no effect on the pupil diameter in the normal eye. However, 10% phenylephrine in combination with topical atropine is reported to be useful in reversing pupillary spasm in some stubborn cases of anterior uveitis, although there is no pharmacological evidence to support any additive mydriatic effect when the two agents are used together. 

The predominant actions of phenylephrine are on the cardiovascular system. Parenteral administration causes a rise in systolic and diastolic pressures due to peripheral vasoconstriction. Accompanying the pressor response to phenylephrine is a marked reflex bradycardia that can be blocked by atropine after atropine, large doses of the peripheral resistance is considerably increased. Circulation time is slightly prolonged, and venous pressure is slightly increased venous constriction is not marked. Most vascular beds are constricted renal, splanchnic, cutaneous, and limb blood flows are reduced, but coronary blood flow is increased. Pulmonary vessels are constricted, and pulmonary arterial pressure is raised. 

Achari, R.G. Jacob, J.T. A study of the retention behavior of some basic drug substances by ion-pair HPLC. J.Liq.Chromatogn, 1980, 3, 81-92 [also N-acetylprocainamide, antazoline, atropine, caffeine, chlorpheniramine, ephedrine, epinephrine, naphazoline, papaverine, pheniramine, phenylephrine, phenylpropanolamine, procainamide, quinidine, scopolamine, xylocaine]... 

Noninterfering acebutolol, acetaminophen, acetazolamide, alprenolol, apraclonidine, atenolol, atropine, betamethasone, betaxolol, bupivacaine, caffeine, Q clopentolate, dexa-methasone, diphenhydramine, erythromycin, haloperidol, lidocaine, phenylephrine, polymyxin B, procaine, scopolamine, timolol, tropicamide... 

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