Lecture 2 - Pharmaceutics Flashcards
What is pharmaceutics?
The science of dosage design and its importance to patients
In drug development, what does the first or discovery phase involve?
- Isolation or synthesis of a chemical entity which shows some specific pharmacological action and the serious toxicological effects
- Once the material chemically characterized it can be considered a drug and it enters the second phase of the development process
What is the second phase in drug development? What does it involve?
It is the pharmaceutic phase. It involves:
- pharmaceutical characterization of the drug
- fabrication of a suitable dose form
- testing and evaluation of the finished product in terms of stability and bioavailability (how much gets to where it actually needs to be)
Pharmaceutics is a broad term and encompasses several general areas. Name them
Physical pharmaceutics
Dosage form design
Fabrication
Microbiology
How is physical pharmaceutics involved in pharmaceutics?
It’s an understanding of the basic physical chemistry necessary for the efficient design of a dosage form
How is dosage form design involved in pharmaceutics?
It’s designing and formulating the medicine
How is fabrication involved in pharmaceutics?
It’s the manufacture of the medicine on both small (compounding) and a large (pharmaceutical technology) scale
How is microbiology involved in pharmaceutics?
The avoidance or elimination of microorganisms in the medicine
Medicines are a combination of what?
They are a combination of the drug and a suitable delivery system; medicines are rarely the drug alone but also include additives (excipients) to make a delivery system
Why is the delivery system of a drug important?
It provides a means of administering or introducing the drug into the body in a safe, efficient, reproducible and convenient manner. The selection of suitable additives is the process of formulation and the goal is to be able to get the drug from the dose form to the target tissues in the body
There are three major considerations in the design of dosage form. Name them and explain their importance
- The physicohemical properties of the drug.
- Biopharmaceutical aspects such as how the route of administration affects the rate of extent of drug absorption into the body.
- Therapeutic considerations of the disease state to be treated and the nature or situation of the patient.
These considerations will dictate which dosage form is most appropriate, the specific route of administration and the frequency of dosing
Name different routes of administrations (7)
Oral, rectal, topical, parenteral, respiratory, nasal, ophthalmic
Name the dose forms of the oral route of administration
Solutions, syrups, suspensions, capsules and tablets
Name the dose forms of the rectal route of administration
Suppositories, ointments and solutions
Name the dose forms of the topical route of administration
Ointments, creams, pastes, lotions and transdermal
Name the dose forms of the parenteral route of administration
Injections - solutions, suspensions, implants and emulsions
Name the dose forms of the respiratory route of administration
Aerosols, inhalations and sprays
Name the dose forms of the nasal route of administration
Solutions, sprays and powders
Name the dose forms of the ophthalmic route of administration
Solutions, ointments and inserts
What is preformulation
It is one of the first steps in formulating a dosage form. It is the preliminary gathering of information which will be needed to develop a formulation and to anticipate problems which will have to be dealt with in the design process
Name the steps usually involved in preformulation
Assay development
Solubilty characteristics
Solid state characteristics
Stability
Describe the assay development step in preformulation
Dosage formulation requires a method of measuring the drug both quantitatively and qualitatively. At least one of the methods will need to be stability-indicating
Describe the solubility characteristics step in preformulation
In most cases, the drug needs to dissolve before it can be absorbed into the body.
Need to determine water solubility, partition coefficient and dissolution characteristics; if ionizable functional groups are present, need to know pKa and possible salt forms; may need information about solubility in other solvents (alcohol, propylene glycol and glycerin)
Describe the solid state characteristics step in preformulation
For solid dose forms in particular we need to know crystalline properties and polymorphism, flow and compression properties, particle size and melting point
Describe the stability step in preformulation
For all dose forms, we need to know the nature of degradation; effect of temperature, pH, light and oxygen compatibility, hydroscopicity and vapor pressure
Name some of the problems that may be dealt with in the preformulation phase
Poor water solubility of the drug
The drug may degrade in stomach acid or be affected by digestive enzymes
The drug may degrade when in solution or exposed to light, heat or oxygen
Define pharmaceutical care
A patient-centered, outcomes-oriented pharmacy practice that requires the pharmacist to work in concert with the patient and other involved health-care providers to promote health, to prevent disease and to assess, monitor, initiate and modify medication use to assure that drug therapy regimes are safe and effective
What is the roles and responsibilities of a pharmacist with regards to pharmaceutics?
Pharmacists must ensure that the prescribed medication is appropriate, that the dose is correct and that the correct medication is dispensed and appropriately labeled
What is the roles and responsibilities of a pharmacist with regards to the patient or caregiver?
Pharmacists must ensure the patient or caregiver understands:
- the purpose of the medication and the goals and timelines of the therapy and what to do if the goals are not being met
- what the dose of the medication is, how to ensure and administer it and what the meanings of any auxiliary labels are
- possible adverse effects and what to do should any of these occur
- the proper storage conditions for the medication
Pharmaceutics converging with pharmaceutical care can best be illustrated with some examples. Name them
Compounding, compatibility, stability, problem solving,
Describe how compounding can be involved with pharmaceutics converging with pharmaceutical care
In some situations, an appropriated dose form is not commercially available so the pharmacist may be called upon to extemporaneously prepare a suitable dose form. The pharmacist must be concerned and knowledgeable about stability and bioavailability of compounded product
Give some examples of how compounding can be involved with pharmaceutics converging with pharmaceutical care
The patient may not be able to take a solid oral dose form such as a capsule or tablet and so a liquid preparation such as a suspension may be compounded.
The dose forms commercially available are of an inappropriate strength. A capsule dose form is often prepared in these cases
Describe how compatibility can be involved with pharmaceutics converging with pharmaceutical care
Occasionally there is an advantage to mixing drugs together before administration but there may be issues of incompatibility or when mixing the drugs leads to solubility or stability problems. By understanding the chemical nature of the drugs and how the manufacturer them, the pharmacist will have some insight regarding whether it is acceptable to mix these together
Describe how stability can be involved with pharmaceutics converging with pharmaceutical care
Some drug products are stored at reduced temperature to increase the shelf-life of the product. Occasionally a product is stored under different conditions and must make a judgment as to whether the product is still suitable for use. Although we would always want to be conservative, our training in pharmaceutics can give us an informed basis on which to make that judgment
Describe how problem solving can be involved with pharmaceutics converging with pharmaceutical care
Parenteral nutrition is providing nutrition intravenously to patients that are unable to eat. The mixtures contain amino acids, carbohydrates, electrolytes, fat emulsion, vitamins and trace minerals. Combinations of phosphate and calcium can form water-insoluble salt but by the use of pH adjustment and managing the proportions of phosphate to calcium this problem can be avoided. A problem arose with PN solutions used for premature neonates where the cannula (plastic needle) sometimes became plugged with an insoluble material which was eventually identified as calcium phosphate
