Oral route dosage forms

Antiemetics can be administered either intravenously or orally in this situation, depending on patient characteristics such as ability to take oral medications, dosage form availability, and cost considerations.5,10 The intravenous and oral routes are equally effective. When used at equipotent doses, the 5-HT3 antagonists have similar efficacy in preventing acute CINV, despite pharmacokinetic and receptor binding affinity differences.5,10,36... 

Rizatriptan has an oral bioavailability of about 45% and reaches peak plasma levels within 1 to 1.5 hours after oral ingestion of tablets of the drug. An orally disintegrating dosage form has a somewhat slower rate of absorption aiding peak plasma levels of the drug 1.6 to 2.5 hours after administration. The principal route of metabolism of rizatriptan is via oxidative deamination by MAO-A. 

Different oral liquid dosage forms offer the possibility to adjust the dosage form optimally to the requirements. The options are solutions, suspensions, emulsions or solubilisates. The flow scheme in Fig. 5.1 shows a route to the oral liquid form that is to be preferred due to the qualities of the active substance, particularly solubility, stability and taste. The required concentration influences the choice as well. 

P2-Agonists cause airway smooth muscle relaxation by stimulating adenyl cyclase to increase the formation of cyclic adenosine monophosphate (cAMP). Other non-bronchodilator effects have been observed, such as improvement in mucociliary transport, but their significance is uncertain.11 P2-Agonists are available in inhalation, oral, and parenteral dosage forms the inhalation route is preferred because of fewer adverse effects. 

An alternative to the oral route is the buccal mucoadhesive system. The Striant buccal system adheres to the inside of the mouth and the testosterone is absorbed through the oral mucosa and delivered to the systemic circulation. There is no first-pass effect, as the liver is bypassed by this route of administration. Patients apply a 30-mg tablet to the upper gum twice daily. The cost is similar to that of the patch or gel. Side effects unique to this dosage form include oral irritation, bitter taste, and gum edema. 

The most common extravascular route is oral. When a solution or a rapidly dissolving solid dosage form is given orally, the absorption process often obeys first-order kinetics. In these cases, absorption can be characterized by evaluating the absorption rate constant, ka, using plasma concentration versus time data. 

Whenever a drug is administered by an extra-vascular route, there is a danger that part of the dose may not reach the blood (i.e., absorption may not be complete). When the intravenous route is used, the drug is placed directly in the blood therefore an IV injection is, by definition, 100% absorbed. The absolute bioavailability of an extravascular dosage form is defined relative to an IV injection. If IV data are not available, the relative bioavailability may be defined relative to a standard dosage form. For example, the bioavailability of a tablet may be defined relative to an oral solution of the drug. 

If the areas under the curves are denoted by A, then (based on equal dose) All/Al is the fraction absorbed by oral route. Alll/All is the fraction efficiency of the solid dosage form. The reason for this latter is, of course, that the solid dosage form has to dissolve before the drug contained in it is available for absorption. It is the latter ratio that is important to the investigating pharmaceuticist, and therefore the outcome of the parenteral form is actually not a consideration from a formulation point of view. It is critical overall and if it is low, it may, at the point of parenteral data acquisition, be advisable to stop the program and evaluate the possibility of derivatives that would give better availability. 

Historically, the oral route of administration has been used the most for both conventional and novel drug-delivery systems. There are many obvious reasons for this, not the least of which would include acceptance by the patient and ease of administration. The types of sustained- and controlled-release systems employed for oral administration include virtually every currently known theoretical mechanism for such application. This is because there is more flexibility in dosage design, since constraints, such as sterility and potential damage at the site of administration, axe minimized. Because of this, it is convenient to discuss the different types of dosage forms by using those developed for oral administration as initial examples. 

Where an unusual excipient is chosen, or where an established excipient is chosen for a dosage form that results in its administration by a novel route of administration, then additional data will need to form part of the application. In effect, a novel excipient will need to be supported by data similar to those required for a new drug, with full supporting data including composition, function, and safety. Novel excipients include the components of the matrix in prolonged release products, new propellants, and new permeability enhancers. The exception to this need for extensive supporting data would be for a material already approved for food use and administered by the oral route or a material already approved for cosmetic use with a topical route of administration. In all cases the quality of the excipients has to be described adequately and shown to be satisfactory (which will depend on its role). 

Comparative bioavailability data are discussed where a number of different dosage forms/routes of administration have been used during the development process, e.g., tablets, capsules, oral solutions, granules, and injections. 

Oral Administration. Oral administration is the preferred route of administration. There is a general consensus among pediatricians and parents that children younger that 5 years of age have great difficulty with, or are unable to swallow, a solid oral dosage form. Manufacturers, therefore, have developed liquid formulations for many of the commonly used pediatric products. The liquid dosage form, however, is not free of problems. Liquid products are often unstable and have short expiration dates accurate measurement and administration of the prescribed dose is also a problem, especially in infants. 

Oral Dosage Forms. The advantages of oral dosage formulations have already been discussed. It appears that this route of delivery is preferred by physician, patients, and manufacturers alike. The relatively low cost of oral dosage forms makes them a... 

Oral (PO = per os) By the mouth. Oral administration is the most common route employed for a variety of dosage forms tablets, capsules, liquids, suspensions. The major site of absorption is the small intestine. Alcohol is absorbed from the stomach. 

Drug deliveiy to the colon by the oral route depends on gastric emptying and the small-bowel transit time. Drugs taken before meals usually pass out of the stomach within 1 hr, but can take up to 10 hr if taken after a meal. The transit time in the small intestine is relatively constant, ranging between 3 and 4 hr, regardless of various conditions such as physical state, size of dosage form, or presence of food in the stomach [9]. 

Absorption - Theophy ne is well absorbed from oral liquids and uncoated plain tablets maximal plasma concentrations are reached in 2 hours. Rectal absorption from suppositories is slow and erratic, the oral route is generally preferred. Enteric-coated tablets and some sustained-release dosage forms may be unreliably absorbed. 

Drugs are administrated by intravenous routes or ex-travascular routes including oral, sublingual, subcutaneous, intramuscular, rectal (by enema or suppository), and transdermal. Available dosage forms include suspensions, immediate-release capsules or tablets, sustained-release capsules or tablets, and enteric-coated capsules or tablets that resist dissolution in the acidic pfi of the stomach. 

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