Cyclic infusion

Continuous drip or cyclic infusion 50 to 125 ml infused per hour at a slow rate over a 24-hour period using an infusion pump (Kangaroo set). Used for treating critically ill patients and patients who have a feeding tube in their small intestines. 

Polycarbonates were first prepared by Einhom in 1898 by reacting the dihydroxybenzenes, hydroquinone and resorcinol, separately with phosgene in solution in pyridine. The hydroquinone polycarbonate was an infusible and insoluble crystalline power whereas the resorcinol polymer was an amorphous material melting at about 200°C. The third dihydroxybenzene, catechol, yields a cyclic carbonate only, which is not surprising bearing in mind the proximity of... 

In order to account for the nonvolatility, infusibility, and limited solubility, Leuchs postulated polymerization of the ground type cyclic compound, as indicated by the subscript x in his formula given above. It is now well established that linear polypeptides are produced on decarboxylation of the N-carboxyanhydrides of a-amino acids, and under favorable conditions the chain length may be fairly large. Leuchs favored the view that strained rings, i.e., those of other than five or six... 

Cyclic EN has the advantage of allowing breaks from the infusion system, thereby increasing mobility, especially if EN is administered nocturnally. 

Cyclic PN (e.g., 12 to 18 hours/day) is useful in hospitalized patients who have limited venous access and require other medications necessitating interruption of PN infusion, to prevent or treat hepatotoxicities associated with continuous PN therapy, and to allow home patients to resume normal lifestyles. Patients with severe glucose intolerance or unstable fluid balance may not tolerate cyclic PN. 

Parent (unsubstituted) PF was first synthesized electrochemically by anodic oxidation of fluorene in 1985 [266] and electrochemical polymerization of various 9-substituted fluorenes was studied in detail later [220,267]. Cyclic voltammogram of fluorene ( r1ed= 1.33 V, Eox = 1.75 V vs. Ag/Ag+ in acetonitrile [267]) with repetitive scanning between 0 and 1.35 V showed the growth of electroactive PF film on the electrode with an onset of the p-doping process at 0.5 V (vs. Ag/Ag+). The unsubstituted PF was an insoluble and infusible material and was only studied as a possible material for modification of electrochemical electrodes. For this reason, it is of little interest for electronic or optical applications, limiting the discussion below to the chemically prepared 9-substituted PFs. 

Non-peptide inhibitors of thrombin (obtained by random screening procedures) include compounds based around benzothiophene (e.g. 155) and other ring systems and cyclic and linear oligocarbamate derivatives (e.g. 156). The benzothiophene derivative 155 showed antithrombotic efficacy in a rat model of thrombosis after infusion (ED50 2.3 mg/kg/h). The cyclic oligocarbamate tetramer 156 inhibited thrombin with an apparent K[ of 31 nM. 

Cyclicity of administration is vital in the use of 5-FU as a radiosensitizer. The concept of cyclical treatment has been well established in cancer chemotherapy and alien to classical radiation therapy (where it is termed split-course therapy). 5-FU radio-sensitizes tumor tissue as well as normal cells. However, this normal tissue radio-sensitizationis limited to the irradiated field. Suitable fractionation (i.e., cyclical therapy) can permit rapid normal tissue recovery (23). The results of infused 5-FU and radiation in head and neck cancer supports the principle that cyclical treatment with 5-FU does not suffer from the limitations apparent in split-course radiation treatments. 

Byfield JE, Sharp TR, Tang S, et al. Phase I and II trial of cyclical 5-day infused 5-fluorouracil and coincident radiation in advanced cancer of the head of neck. J Clin Oncol 1983 2 406-413. 

Solid-state (topochemical) polymerization of cyclic disulfur dinitride to poly(sulfur nitride) (or polythiazyl), -fSN, occurs on standing at ambient temperature or higher [Banister and Gorrell, 1998 Labes et al., 1979 Ray, 1978]. Disulfur dinitride is obtained by sublimation of tetrasulfur tetranitride. Polythiazyl is a potentially useful material, since it behaves like a metal. It has an electrical conductivity at room temperature about the same order of magnitude as a metal like mercury and is a superconductor at 0.3°C. Polythiazyl also has high light reflectivity and good thermal conductivity. However, it is insoluble and infusible, which prevents its practical utilization. 

Epoprostenol is the natural occurring prostacyclin which is formed in vascular endothelial cells. It increases cyclic AMP in the thrombocyte and is a strong platelet aggregation inhibitor. It is used to prevent thrombotic complications during hemodialysis when heparin is contraindicated. As its duration of action is no longer than 30 minutes it has to be given as an intravenous infusion. 

It is a relatively selective inhibitor of cyclic GMP, cyclic AMP-PDE (phosphodiesterase) type 111 family. It causes vasodilatation with a consequent decrease in systemic vascular resistance. It increases both the force of contraction and velocity of relaxation of cardiac muscles. It is administered IV 0.75 mg/kg/min as a bolus dose followed by 5-10 pg/kg/min IV infusion and total dose not to exceed 10 mg/kg. 

It is relatively selective inhibitor of peak III cyclic AMP phosphodiesterase isoenzyme in cardiac and vascular muscle. In patients with CHF, it produces dose related and plasma concentration related increase in the maximum rate of increase of left ventricular pressure. Milrinone has a direct inotropic and direct arterial vasodilator activity. It is administrated by IV infusion 0.50 mg/kg over 10 min with a maximum daily dose of 1.13 mg/kg. 

A. General description Octreotide is a long-acting cyclic octapeptide (molecular weight 1.0 kDa) with pharmacologic actions mimicking those of the natural hormone somatostatin. The usefulness of natural somatostatin is limited by its extremely short duration of action, which requires continuous infusion. Octreotide is a molecular form (an octapeptide with two D-amino-acid substitutions) that overcomes the problem of short duration of action. 

The reaction of dibasic acids with diamines was reported in the early literature [6-13] to give low molecular weight cyclic amides as infusible and insoluble products. It was Carothers [14-18] who first recognized that polymeric amides were formed by the reaction of diamines with dibasic acids. Many of the polyamides were able to be spun into fibers and the fibers were called Nylon by du Pont [14-20]. 

In a randomized, controlled study of cyclic iloprost or nifedipine in 46 patients with systemic sclerosis, the predictable adverse effects of iloprost (headache, nausea and vomiting, and diarrhea) were common but quickly resolved after the end of the infusion (5). They rarely required a temporary dose reduction. Hypotension occurred less often than with nifedipine. 

Caspofungin is a cyclic polypeptide that inhibits synthesis of the fungal cell wall. It can be used in systemic mycoses due to as-pergillus fungi when amphotericin B or itroconazole cannot be employed. It is given by infusion and causes various adverse effects. 

Besides common therapeutic indications, G-CSF has also been used in severe chronic neutropenic diseases (congenital, cyclic, idiopathic), aplastic anemia, and neonatal neutropenia. G-CSF is sometimes used in healthy volunteers to mobilize blood progenitor cells or granulocytes before infusion into neutropenic patients. 

Kerin MJ, Pickford IR, Jaeger H, Couse NF, et al. A prospective and randomised study comparing the incidence of infusion phlebitis during continuous and cyclic peripheral parenteral nutrition. Chn Nutr 1991 10 315. 

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