Reflex Depression

K Ketocyclazocine Miosis, flexor reflex depression, sedation, no change in pulse rate... 

Fig. 1. The effect of the dosage of demerol on the analgesic index (reflex depression index). The subcutaneous dosage of demerol for rats is plotted on the abscissa and the reflex depression index on the ordinate. The index is given by x/ o, where to is reaction time prior to demerol and t is the altered reaction time, (Copied from J. Lee (4).)...

Foster and Carman calculated their analgesic index (actually a reflex depression index) from the relation, where U is the normal re-... 

Fio. 3. The relationship between doses of morphine and demerol required to induce equivalent reflex depression in rats. The dose of morphine is plotted on the abscissa and the equivalent dose of demerol on the ordinate. Calculated from Figs. 1 and 2. C(d)/2)(m) - 12.64 - 4.89/D(m). 

Two curves using the Foster-Carman index are shown in Fig. 1 and Fig. 2. From Figs. 1 and 2, according to Lee, at an index of 1.25 morphine is 20 times as active as demerol, whereas at an index of 1.40 it is 12 times as active this indicates the desirability of comparing a series of compounds at the same analgesic (reflex depression) level (4). 

Fig, 4. Analgesic effect (reflex depression) of 3-oxy-iV-methylmorphinan hydrochloride (I), morphine hydrochloride (II), and codeine phosphate (III) on white mice. Thermal irradiation of constant intensity was applied to the tail until a flick was obtained or up to twice the duration required without medication. Drugs were administered subcutaneously. On the ordinates are plotted on a linear scale the per cent of the mice not reacting to the thermal irradiation. Dosage is plotted on the abscissa on a logarithmic scale. (Copied from W. Wirth (45).)... 

The analgesic doses (reflex depression in cats) were given by Small and Eddy (2) as 3.56 mg. of methyldihydromorphine per kilogram, and as 0.75 mg. of morphine per kilogram. Obviously methyldihydromorphine is the less effective substance. (There may be an ambiguity in the analgesia data obtained from mice and cats or the methyldihydromorphine of Small and Eddy may be a different compound from the 6-methyldihydromorphine discussed by Isbell and Fraser.)... 

Morphine has certain undesirable side effects. Among these are respiratory depression, nausea, and vomiting, depression of the cough reflex, cardiovascular depression and hypotension, smooth muscle contraction (constipation), and histamine release (93). Morphine s onset of action, duration, and low therapeutic indices have prompted a search for a more effective opiate iv anesthetic. Extreme simplification of the complex morphine molecule has resulted in anilido —piperidines, the fentanyl class of extremely potent opiate iv anesthetics (118,119). 

The cardiac effects of the calcium antagonists, ie, slowed rate (negative chronotropy) and decreased contractile force (negative inotropy), are prominent in isolated cardiac preparations. However, in the intact circulation, these effects may be masked by reflex compensatory adjustments to the hypotension that these agents produce. The negative inotropic activity of the calcium antagonists may be a problem in patients having heart failure, where contractility is already depressed, or in patients on concomitant -adrenoceptor blockers where reflex compensatory mechanisms are reduced. 

Codeine (morphine methyl ether) resembles morphine in its general effect, but is less toxic and its depressant action less marked and less prolonged, whilst its stimulating action involves not only the spinal cord, but also the lower parts of the brain. In small doses in man it induces sleep, which is not so deep as that caused by morphine, and in large doses it causes restlessness and increased reflex excitability rather than sleep. The respiration is slowed less than by morphine (cf. table, p. 261). Cases of addiction for codeine can occur but according to Wolff they are rare. The best known ethers of morphine are ethylmorphine and benzyl-morphine [cf., table, p. 261), both used to replace morphine or codeine for special purposes. 

The nurse must report symptoms of succinimide overdosage immediately. Symptoms of overdosage in dude confuson, sleepiness, unsteadiness flaccid muscles slow shallow respirations nausea, vomiting, hypotension, absent reflexes nd CNS depression leading to coma. It is important to report symptoms to the primary health care provider immediately. Therapeutic serum blood levels of ethosuximide (Zarontin) range from 40 to 100 mcg/mL... 

Anorexia, nausea, vomiting, mental depression, confusion, delayed or impaired thought processes, drowsiness, abdominal distention, decreased bowel sounds, paralytic ileus, muscle weakness or fatigue, flaccid paralysis, absent or diminished deep tendon reflexes, weak irregular pulse, paresthesias, leg cramps, ECG changes Hyperkalemia... 

Adverse reactions seen with magnesium administration are rare. If they do occur, they are most likely related to overdose and may include flushing, sweating, hypotension, depressed reflexes, muscle weakness, and circulatory collapse (see Display 58-2). 

Death from overdose of barbiturates may occur and is more likely when more than 10 times the hypnotic dose is ingested. The barbiturates with high lipid solubility and short half-lives are the most toxic. Thus the lethal dose of phenobarbital is 6—10 g, whereas that of secobarbital, pentobarbital, or amo-barbital is 2-3 g. Symptoms of barbiturate poisoning include CNS depression, coma, depressed reflex activity, a positive Babinski reflex, contracted pupils (with hypoxia there may be paralytic dilation), altered respiration, hypothermia, depressed cardiac function, hypotension, shock, pulmonary complications, and renal failure. 

Distal sensory neuropathy AIDS Subacute or chronic Distal sensory loss and neuropathic pain depressed or absent ankle reflexes Immune dysfunction macrophage-mediated axonal injury... 

Analgesia Depressed reflexes Feeling of warmth Anxiolysis Constipation Drying up of secretions... 

Clemens S., Hochman S. (2004). Conversion of the modulatory actions of dopamine on spinal reflexes from depression to facilitation in D3 receptor knock-out mice. J. Neurosci 24, 11337-45. 

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