Sympathomimetics effects

The appetite-suppressing effect of (3-phenylethylamine drugs is either related to their sympathomimetic effect (metamphetamine, phentermine, diethylpropion), to... 

Additive sympathomimetic effects may develop when decongestants are administered with other sympathomimetic drug s (see Chap. 22). Use of the nasal decongestants with the MAOIs may cause hypertensive crisis. Use of a decongestant with beta-adrenergic blocking dragp may cause hypertension or bradycardia. When ephedrine is administered with theophylline, the patient is at increased risk for theophylline toxicity. 

The answer is local anesthetic properties it can block the initiation or conduction of a nerve impulse. It is biotransformed by plasma esterases to inactive products. In addition, cocaine blocks the reuptake of norepinephrine. This action produces CNS stimulant effects including euphoria, excitement, and restlessness Peripherally, cocaine produces sympathomimetic effects including tachycardia and vasoconstriction. Death from acute overdose can be from respiratory depression or cardiac failure Cocaine is an ester of benzoic acid and is closely related to the structure of atropine. 

Tests are made by examining the inhibition caused by the substance on the sympathomimetic effects of injected adrenaline and of sympathetic nerve stimulation. Among the recently re-oommended anti-adrenaline drugs are iminazole derivatives (e.g. priscol (VIII))2 and / -haloalkylamines (e.g. dibenamine (IX)). The action of dibenamine is almost certainly that of destroying the receptor patches in the effector organ (p. 37). 

Autonomic Cocaine has stong sympathomimetic effects due to inhibition of norepinephrine reuptake, and perhaps central mechanisms as well. Effects include those typical of sympathetic autonomic activation. Cardiovascular and cerebrovascular effects are prominent. 

Khat produces sympathomimetic effects, increasing heart rate and blood pressure. When khat is chewed, the increases are gradual, maximizing at about 2 hours and lasting for 4 hours. However, tolerance develops to blood pressure and heart rate effects in habitual users. Mydriasis and increases in respiration also occur. Cathinone induces thermogenesis in brown adipose tissue, which is mediated by jS-adrenergic receptors (Tariq et al. 1989). 

Autonomic LSD produces sympathomimetic effects, including pupil dilation, tachycardia, increased blood pressure, piloerection, hyperreflexia, nausea, and fever. 

Phenobarbital. This is put into Tedral to counteract the sympathomimetic effects of the ephedrine. it is a good sedative once separated from the ephedrine. 

Cyclohexylamine has long been known to be pharmacologically active and has sympathomimetic effects on the heart and blood pressure. However, it is not particularly potent. ... 

Tyramine, the only indirect-acting compound, exhibits sympathomimetic effects by causing the release of endogenic norepinephrine, and it has only found practical use in experiments. It inactivates monoaminooxidase very quickly. It has no practical clinical use. 

As drugs of mixed action, amphetamines activate adrenergic receptors and simultaneously release endogenic catecholamines (norepinephrine and dopamine) from neurons of the brain and periphery. Sympathomimetic effects on the periphery are very similar to those of ephedrine. Amphetamine elevates systolic and diastolic blood pressure and has weakly expressed, broncholytic action. These effects are more prolonged, yet less expressed, than with epinephrine. The distinctive feature of amphetamines is their psychostimulatory activity. Larger doses can cause hallucinations and mental conditions similar to paranoid schizophrenia. As a sympathomimetic, amphetamine is sometimes used for uterine inertia. Synonyms of amphetamine are phenamine and benzedrine. 

Phentolamine is also a derivative of imidazoline that exhibits a direct a-adrenoblocking, muscle-relaxant effect on smooth muscle as well as cholinomimetic, histamine, and sympathomimetic effects. The chemical variation of its stmcture permits a few of its properties to be more expressed. For example, the aforementioned tolazoline, 2-benzyl-2-imidazoline, a structural analog of phentolamine, has more of an expressed muscle-relaxant effect on smooth muscle than an a-adrenoblocking effect. 

The hydroxyl groups of the phenyl ring are a prerequisite for the activation of all adrenoceptors, if both are absent the molecule has only an indirect sympathomimetic effect (see Fig. 5). Indirect sympathomimetics only have a -, a2 and -adrenoceptor activity since they act via an increase of the noradrenaline concentration in the synaptic cleft. If the methyl-group at the N-position of adrenaline is substituted by a longer or more bulky moiety the molecule gains affinity for the and loses affinity for O -adrenoceptors. An isopropyl moiety is already the optimum for the affinity towards 0-adrenoceptors (isoprenaline), larger substituents enhance only the binding to the 2-subtype (for example fenoterol). 

Pindolol, oxprenolol, acebutolol and alprenolol are /3-blocker ISA. A weak sympathomimetic effect can be seen in the heart if almost all /3-adrenoceptors are occupied by these compounds. The advantage of ISA might be that a basal /3-adrenergic stimulus is left. In some vessel beds a reduction of the vascular activity and thereby a reduction in resistance has been observed with pindolol which might be beneficial in the therapy of hypertension. The pharmacodynamic and -kinetic properties of some frequently used jS-blocker are shown in Table 2. 

B) Indirect sympathomimetic effects in the periphery due to release of norepinephrine... 

Overdose produces excessive sympathomimetic effects, including vomiting, tremor, hyperreflexia, seizures, confusion, hallucinations, and diaphoresis. 

Systemic sympathomimetic effects may occur with either route headache, hypertension, weakness, sweating, palpitations, tremors. 

If a patient does not respond to one MAO I, or if there appears to be a loss of efficacy over time, it may be reasonable to try a second. When switching from a hydrazine-based MAOl (e.g., phenelzine or isocarboxazid) to a nonhydrazine MAOl (e.g., tranylcypromine), one should wait at least 2 weeks. This is because the nonhydrazine MAOl, tranylcypromine, produces NE uptake inhibitory and sympathomimetic effects similar to dextroamphetamine and may cause a toxic reaction if initiated within 2 weeks following MAO inhibition by another agent (261). 

Although ketamine produces direct myocardial depression, it has significant indirect cardiovascular effects through sympathomimetic effects and stimulation of the vasomotor centre. The heart rate and systolic blood pressure increase by 30% and occasionally up to 100%. Owing to the increased cardiac work and myocardial consumption, ketamine adversely affects the balance between myocardial oxygen supply and demand. Consequently, it is not recommended for use as the sole agent in adults with severe cardiovascular disease. However, the same haemodynamic effects, particularly the raised systemic vascular resistance, make the agent particularly suitable for children with cyanotic heart disease. 

Sympathomimetic effects (from NA re-uptake inhibition) and antimuscarinic effects can cause a sinus tachycardia. Postural hypotension may occur as a result of sympatholytic al-adrenoceptor antagonism. With overdoses of these drugs, there is a reduced re-uptake of catecholamines, resulting in arrhythmias and hypertension. Tricyclic compounds have a high... 

These drugs are best avoided in patients with cerebrovascular, cardiovascular and hepatic disorders. Some sympathomimetic effects may occur, mainly mild tremor and occasionally cardiac arrhythmias. Apparent anticholinergic effects may also occur but these are the result of sympathetic potentiation in tissues with dual cholinergic/adrenergic innervation, e.g. pupil. Sympatholytic effects can also occur, principally postural hypotension, because of synthesis of relatively inactive false transmitters, e.g. octopamine, in nerve terminals following inhibition of MAO and activation of alternative metabolic pathways. 

Epinephrine Nonselective and agonist Bronchodilation plus all other sympathomimetic effects on cardiovascular and other organ systems (see Chapter 9) Anaphylaxis, asthma, others (see Chapter 9) rarely used for asthma (B 2-selective agents preferred) Aerosol, nebulizer, or parenteral see Chapter 9... 

Cocaine Same as above also has sympathomimetic effects Same as above Procedures requiring high surface activity and vasoconstriction Topical or parenteral duration 1-2 h Toxicity CNS excitation, convulsions, cardiac arrhythmias, hypertension, stroke... 

Clinical syndromes from LSD-25, mescaline, and the indoleamincs arc similar, Somatic symptoms are nausea, dizziness, loss of appetite, blurred vision, paresthesia, weakness, drowsiness, and trembling. These result frequently and are usually associated with sympathomimetic effects, such as increased pulse rate and slight temperature elevation. Perceptual and psychic changes are marked. Visual illusions and vivid hallucinations, decreased concentration, slow thinking, depersonalization, dreamy states, changes in mood, and often anxiety are commonly found. 

---