Drug administration intravascular

Let us consider some drug administration practicalities. Up to now, the administered amounts were considered as initial units introduced simultaneously into several compartments at the beginning of the experiment. These amounts were considered as initial conditions to the differential equations describing the studied processes. Nevertheless, this concept seems to have limited applications in pharmacokinetics. In this section, we develop the probabilistic transfer and retention-time models associated with an extravascular or intravascular route of administration. 

Transdermal drug delivery is an approach used to deliver drugs through the skin for therapeutic use as an alternative to oral, intravascular, subcutaneous, and transmu-cosal routes. It includes the following categories of drug administration ... 

Intravascular Administration and Blood Collection. Drug administration and blood collection can be accomplished by syringe, vac-u-tainer and cannula in most fish species. The major determinants for method selection are anatomical, size, and experimental design considerations. 

Fig. 9.21. Typical plasma concentration versus time profile following administration of a dose of a drug by intravascular (o) and extravascular routes ( ).

Important features of the intravascular route of drug administration... 

A typical plot of plasma and/or serum concentration against time, following the administration of the dose of a drug by intravascular route, is illustrated in Fig. 1.3. 

Figure 6.18 Administration of a drug by intravascular (IV) and extravascular (oral) routes (onecompartment model). Even for administration of the same dose, the value of plasma concentration (Cp) at time zero [(Cp)o] for the intravenous bolus may be higher than the intercept for the extravascular dose. This will be determined by the relative magnitudes of the elimination rate constant (K) and the absorption rate constant (fQ,) and by the size of fraction absorbed (f) for the extravascular dosage form. Xo, oral dose of drug Xq, IV bolus dose of drug.

Figure 7.14 Plasma concentration (Cp) versus time following the administration of an identical dose of a drug by intravascular and extrovascular routes (fast oral absorption).

Figure 7.15 represents plasma concentration versus time data following the administration of an identical dose of a drug by intravascular or extravascular routes. The absorption of drug from the extravascular route can be described as slow but virtually complete. Since peak time is long and peak plasma concentration is much lower than the initial plasma concentration for an intravenous bolus, this can be attributed to slower absorption. The (AUC)q for the intravascular and extravascular routes may be identical. If this assumption is applicable, then the extent of drug absorption is identical. 

This Appendix presents the general treatment and derivation of equations for the plasma concentration versus time data following the administration of a drug by intravascular (both intravenous bolus and infusion) and extravascu-lar routes of administration. Derivation of equations is limited to one- and two-compartment... 

Several routes of drug administration, including extravascular (oral, intramuscular, subcutaneous, transdermal, inhalation, etc.) and intravascular routes (intravenous and intra-arterial), are used to deliver drugs into the body. Oral administration of drugs is the most common route because it is... 

The MAOIs cause significant hypotension, which is often the dose-limiting side effect of these drugs. Expansion of intravascular volume through administration of salt tablets or fludrocortisone may be an effective treatment. 

This section will review how physiological factors at the site of injection impact the design of dosage forms and affect choice of excipients. First, pharmacokinetic factors affecting rates of delivery of drug to the blood will be considered. Then, biocompatibility or safety issues will be addressed. This analysis focuses on the intravascular (IV), IM, and SC routes of administration. 

In practice, it is unlikely to have compartmental models with initial conditions unless there are residual concentrations obtained from previous administrations. Drugs are administered either by extravascular, or intravascular in single or repeated experiments. Extravascular routes are oral, or intramuscular routes, and intravascular are the constant-rate short- and long-duration infusions. 

Parenteral administration is used for drugs that are poorly absorbed from the gastrointestinal (Gl) tract, and for agents such as insulin that are unstable in the Gl tract. Parenteral administration is also used for treatment of unconscious patients and under circumstances that require a rapid onset of action. Parenteral administration provides the most control over the actual dose of drug delivered to the body. The three major parenteral routes are intravascular (intravenous or intra-arterial), intramuscular, and subcutaneous (see Figure 1.2). Each has its advantages and drawbacks. 

Intravascular Intravenous (IV) injection is the most common parenteral route. For drugs that are not absorbed orally, there is often no other choice. With IV administration, the drug avoids the Gl tract and, therefore, first-pass metabolism by the liver. This route permits a rapid effect and a maximal degree of control over the circulating levels of the drug. However, unlike drugs present in the Gl tract, those that are injected cannot be recalled by... 

Rote et al. (1993, 1994) used a carotid thrombosis model in dogs. A calibrated electromagnetic flow meter was placed on each common carotid artery proximal to both the point of insertion of an intravascular electrode and a mechanical constrictor. The external constrictor was adjusted with a screw until the pulsatile flow pattern decreased by 25 % without altering the mean blood flow. Electrolytic injury to the intimal surface was accomplished with the use of an intravascular electrode composed of a Teflon-insulated silver-coated copper wire connected to the positive pole of a 9-V nickel-cadmium battery in series with a 250000 ohm variable resistor. The cathode was connected to a subcutaneous site. Injury was initiated in the right carotid artery by application of a 150 xA continuous pulse anodal direct current to the intimal surface of the vessel for a maximum duration of 3 h or for 30 min beyond the time of complete vessel occlusion as determined by the blood flow recording. Upon completion of the study on the right carotid, the procedure for induction of vessel wall injury was repeated on the left carotid artery after administration of the test drug. 

Postural hypotension is particularly hazardous in susceptible patients, such as the elderly and those with depleted intravascular volume or reduced cardiovascular output. The risk of orthostatic hypotension is markedly increased after parenteral administration. The combination of alpha-adrenoceptor blockade and sedative effects may explain the increased risk of falling when taking neuroleptic drugs (SEDA-12, 52). 

Intravascular hemolysis and biochemical changes and reversible neurological deterioration have been reported following intravenous administration however, it has been questioned whether these findings were directly attributable to dimethyl sulfoxide rather than to concomitant drug therapy or contaminants. " Recently, a hypersensitivity reaction attributed to dimethyl sulfoxide has been reported. ... 

Rapid i.v. administration of tetracyclines can result in hypotension and collapse. This has been attributed to intravascular chelation of calcium and/or a decrease in blood pressure owing to the drug vehicle. The i.v. administration of doxycycline to horses causes tachycardia, systemic arterial hypertension, collapse and death. This reaction may be caused by the highly lipid-soluble doxycycline chelating intracellular calcium, resulting in cardiac neuromuscular blockade. 

Mannitol is another drug used for the treatment of oliguric ART. Mannitol administration (1 g/kg i.v. over 30-60 min) increases plasma osmolality and the resultant shift of fluid into the intravascular... 

RNase (RNAse ribonuclease) An enzyme that cleaves RNA. routes of administration of drugs There are many different routes but common ones include intravascular injection or infusion (into the blood vessels, e.g. by drip, mainly intravenous (into veins) but sometimes intra-arterial (into arteries) intramuscular (injection into muscles) subcutaneous (injection beneath the dermis of the skin) intradermal (injection into the skin) transdermal (across the skin. e.g. from skin patches) topical (application to the skin or mucous membranes) per rectum (by an ointment or suppository into the rectum) intravaginally (by an ointment or pessary into the vagina) intrathecal (by injection into the subarachnoid space of the spinal cord) intranasally (often as a spray) orally (by mouth) inhalation. rRNA ribosomal RNA. 

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