Rate of drug release at any given location within gastrointestinal tract depends on the mechanism by which the drug released from pellets and local environment within git. In order to predict in vivo behavior of dosage forms, knowledge of release mechanism and physiological conditions of git should be understood.
Type of coating and method of applying coating will determine dominant mechanism of drug release from coated pellets. Release kinetic is predominantly determined by the behavior of coating material under physiological conditions of git. Multiparticulates coated for extended release purpose; release the drug by eighter diffusion or erosion or combination of these mechanisms.
Pellets coated with polymer not soluble under gi conditions releases drug by 4 different mechanisms:
1. Solution/ diffusion through the continuous plasticized polymer phase
This mechanism is based on assumption that the polymer forms a continuous phase in which the plasticizer & other additives are homogeneously dispersed. When polymer film is formed, it contains molecular sized openings between crosslinked chains of polymer. Plasticizer & other additives affects wetting of these openings as well as interchain dimensions by changing the crosslinking properties of polymer chains which are critical for diffusion of drug. Mostly, drug molecules diffuse through these openings in a process known as hindered molecular diffusion. It is an activated process wherein thermal fluctuations of chain segments
Absorption – “How the drugs enter the circulation process through the body, and how they resist general breakdown by the stomach, liver, and the intestines”. Some of the factors that affect the absorption of drugs in the body is as follows, “acidity of the stomach, Physiochemical properties, Presence of food in the stomach or intestine, and Routes of administration”,
7. What is the reason for manufacturing a drug as an enteric-coated tablet? (2 points)
After oral administration, APAP is rapidly absorbed by the GI tract; its volume of distribution is
Based on ¨Principles of Pharmacokinetics¨, ¨pharmacokinetics is the study of absorption, distribution, metabolism, and excretion¨ (Ratain 2003). In other words, the drug's pharmacokinetics determines the duration and the intensity of the effect on the body. Absorption rate can be affected by the drug itself, such as: rate of dissolution, lipid solubility, and route (VandeWaa 2016). The absorption process starts by the route of admission, in this case oral. The oral, or by mouth, route of administration for drugs is the most common. When a pill is taken by mouth, it travels down to the stomach, were most pills dissolve. While in the stomach, some kinds of pills are absorbed into the stomach lining, but some move on to the small intestine. Every pill eventually ends up in the bloodstream and circulate through the body to tissues and organs (Howell 2017). Once passive diffusion occurs, the cells absorb the molecules of the medicine. Then, the molecules of the medicine will exit the cells and travel in the bloodstream for the distribution process.
Many molecules, particularly peptides and polypeptides are physically embedded in polymers to create a complex network of interconnecting pores through which the drug could subsequently diffuse. The pore structure and polymer composition is controlled in order to design systems that release the drug at nearly any rate and for nearly
Oral forms of cephalosporins are well absorbed from the gastrointestinal (GI) tract. Absorption is delayed by food, except for in oral ester prodrugs where absorption is
However, PPIs cannot be simply dropped into the stomach because they will not reach their target. They are prodrugs that are activated in the presence of an acidic environment. The drugs must be absorbed by the small intestine and reach the circulation via parietal cells and be exported to the canaliculi of the stomach so that the first nucleophile they see is the PPI. Enteric coatings or admixture with bicarbonate are ways to protect the prodrug from acid before they are systemically
This review presents a survey of challenges associated with formulating MDIs as solution or suspension products with one or more drugs, while considering the physicochemical properties of various excipients and how the addition of these excipients may impact overall product performance of the MDI. Propellants, volatile and nonvolatile cosolvents, surfactants, polymers, suspension stabilizers, and bulking agents are among the variety of excipients discussed in this review article. Furthermore, other formulation approaches, such as engineered excipient and drug-excipient particles, to deliver multiple drugs from a single MDI are also evaluated. The device hardware includes a canister that is appropriately sized to contain sufficient formulation for the required number of doses, a metering valve capable of delivering a consistent amount of drug with each dose delivered, an actuator mouthpiece that atomizes the formulation and serves as a conduit to deliver the aerosol to the patient, and often an indicating mechanism that provides information to the patient on the number of doses
"Absorption depends on the drug’s ability to cross cell membranes and resist extensive breakdown by the stomach, liver, and intestines.
List and describe the four factors that affect the rate of drug distribution. How will you explain an adverse effect to a patient? How is this different than a side effect?
Pharmacokinetics (PK) is a complex process even for healthy patients. The whole body, as a system, remains unpredictable in many of its responses to drugs. That being said we have elucidated many of the body processes and have designed drugs and drug therapy regimens around new evidence and models. PK is broken down into four pats: administration, distribution, metabolism, and excretion. Absorption refers to the drug entering the body; distribution to the spread of the drug to tissues, organs and throughout the blood; metabolism is the processing of drugs by enzymes in the body, such as the cytochrome P450 liver enzymes; and excretion is drug removal from the body. As the body ages, all of these areas is affected.
The hygroscopic nature of a drug is a risk for good aerosolization since moisture uptake can result in agglomeration (Hoppentocht et al., 2015). On the other hand, hydrophobic coating improves the flowability of cohesive powders (Hickey et al., 1990; Yang et al., 2005).
Since ancient times different pharmaceutical formulations were used to deliver different drugs for treatment of various diseases, which played a role in saving the life of thousands of people. For example since discovery of oral rehydration sachets many lives have been saved from dehydration caused from severe diarrhea. Oral liquid preparations have been a preferable choice for many patients and provide better compliance than other dosage forms due to the easiness of administration.
Pharmacokinetics describes what the body does to the drug, as opposed to pharmacodynamics which describes what the drug does to the body. Pharmacokinetic information is required to utilize and increase the drug response. The primary pharmacokinetic disposition parameter is clearance. This is really important to have knowledge of this value and its major parts. For example the fractional renal and hepatic elimination and clearance will allow the clinician to prescribe the correct dosage regimen. The accurate dosage regimen could help the clinicians to obtain an average therapeutic concentration and to predict the effects of various disease states. The other pharmacokinetic disposition parameter which can be utilized in vitro is the volume of distribution. The volume of distribution can be measured at steady-state; this may also vary with changes in physiologic and pathologic conditions of the body2. Clearance and volume of distribution would be expected to vary with changes in
Binders are important constituents of the tablet formulation, which perform at processing time, during compression when powder from inlets arrives in between punch and die cavity. The hold between particles is required at time of compression; otherwise, a solid mass of tablet will not produce (Figure 2 above). Binders provide a bond in between particles thus particles are held together and a tablet attains mechanical strength (Hardik Patel et al., 2011) .The adhesion