Hypotension amphetamine

Because neuronal uptake is necessary for the hypotensive activity of guanethidine, drugs that block the catecholamine uptake process or displace amines from the nerve terminal (see Chapter 6) block its effects. These include cocaine, amphetamine, tricyclic antidepressants, phenothiazines, and phenoxybenzamine. 

Cardiovascular toxicity is also frequently encountered in poisoning. Hypotension may be due to depression of cardiac contractility hypovolemia resulting from vomiting, diarrhea, or fluid sequestration peripheral vascular collapse due to blockade of -adrenoceptor-mediated vascular tone or cardiac arrhythmias. Hypothermia or hyperthermia due to exposure as well as the temperature-dysregulating effects of many drugs can also produce hypotension. Lethal arrhythmias such as ventricular tachycardia and fibrillation can occur with overdoses of many cardioactive drugs such as ephedrine, amphetamines, cocaine, tricyclic antidepressants, digitalis, and theophylline. 

Contraindications If taken too close to bedtime may cause insomnia. If taken while physically exhausted hypotensive properties may be sharply exaggerated. Should not be used by persons with ailment or injury of kidneys, liver, or heart, or inclination towards diabetes or hypoglycemia. MAO inhibitor (see list of dangerous combinations). Anxiety may also occur. Sodium amobarbitol or Librium alleviate this. Imipramine may worsen it. Nauseau may occur from ingestion of yohimbine, but is not likely when snuffed. Can result in heart palpitations, severe blood pressure drop, and breathing difficulties if taken within 48 hours of having taken any amphetamine, even Dexamyl type diet pill. 

Among the materials which may be dangerous in combination with MAO inhibitors are sedatives, tranquilizers, antihistamines, narcotics, and alcohol -- any of which can cause hypotensive crisis (severe blood pressure drop) and amphetamines (even diet pills), mescaline, asarone, nutmeg (active doses), macromerine, ephedrine oils of dill, parsely or wild fennel beer, wine, cocoa, aged cheeses, and other tyrosine-containing foods (tyrosine is converted into tyramine by bacteria in the bowel) -- any of which can cause hypotensive or hypertensive (severe blood pressure rise) crises. 

Amphetamines and other stimulatory anorectic agents, apart from fenfluramine, would be expected to impair the hypotensive effects of adrenergic neuron blocking drugs such as guanethidine. Not only do they release noradrenaline from stores in adrenergic neurons and block the reuptake of released noradrenaline into the neuron, but they also impair re-entry of the antihypertensive drugs (109). 

AMPHETAMINES ALPHA-BLOCKERS Antagonism of hypotensive effect Due to t release of norepinephrine Be aware... 

Amphetamines may antagonize hypotensive effects of veratrum alkaloids and other antihypertensives... 

Chlorpromazine has many actions of which a-adrenoceptor block is a minor one, but sufficient to cause hypotension, and to be clinically useful in amphetamine overdose. 

Amphetamines have also been associated with a syndrome of acute kidney injury and rhabdomyolysis. Several series have described patients following intravenous injection of methamphetamine or phenmetrazine who presented with hyperactivity, fever, chills, sweats, abdominal cramps, diarrhea, and hypotension [177,178]. The patients have developed acute kidney injury which is usually oliguric and associated with classic rhabdomyolysis, similar to cases of cocaine-induced rhabdomyolysis. Several patients have had disseminated intravascular coagulation and liver function abnormalities as well. Methamphetamine abuse has also been associated with accelerated hypertension, unexplained chronic renal failure, acute lead poisoning (a common reagent used in its production utilizes lead acetate) and at least one case of biopsy proven interstitial nephritis the latter patient responded to intravenous corticosteroids but whether the nephritis was truly due to amphetamines remains unproven [179]. 

Reviews on the pharmacology, extractipn and identification, and abuse of amphetamines have appeared. Other studies deal with the pharmacology of various phenethanolamines and of iV-acetoacetyldopa. It is considered likely that the hypotensive and lethal action of the venoms of the bald-faced hornet Vespula maculata and the yellow jacket V. maculifrons is due to the combined action of many constituents. Of these histamine, dopamine, and norepinephrine have now been identified. ... 

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