Week 1: Introduction + Some Basic Pharmacology Flashcards
Smoke and Solids
Burning a dry material will release a drug into the air in smoke which can be absorbed in the lungs
- eg. tobacco, opium, marijuana
Drugs ingested in this way canot be exhaled and must be eliminated through other means
There is risk to damaging the tissues of the respiratory system with this method as many other substances in smoke beyond the drug (eg. tars and hydrocarbons) cause harm like respiratory disease and cancer
Therefore, vapourising a drug is safer
Rate of elimination
Half life = the amount of time it takes to eliminate half of a given blood level of a drug
The exception to this general rule is alcohol
- there is a fixed amount of per unit of time excreted
How do Non-lipid soluble substances cross the blood brain barrier
- There are passive and active transport mechanisms to accomplish this
- Most are accomplished via transmembrane proteins
so, Passive transport (diffusion) - for lipid soluble substances
and facilitated/active transport - for non-lipid soluble or against a concentration gradient
History of Drugs in NZ - Before the arrival of Europeans
- Maori were one of the few societies that didn’t use intoxicants recreationally
- They used psychoactive substances as medicine
eg. Kawakawa - used to treat bladder issues, bruises, as an analgesic and diuretic
eg. Pukatea - used as an analgesic and to treat tuberculosis
eg. Redula Marginata (acts like a cannabinoid)
Vaporising
Refined drugs can be heated until they vaporise and the vapours can be inhaled
This is better than smoking, but not a perfect method as moisture, warmth and sugar (from vape syrups for example) can promote bacterial infection in the lungs.
Transdermal administration
- Transdermal
= absorbed through the skin
Drug Antagonism
= When one drug dimishes the effect of the other
- can decrease potency and effectiveness
shifts the dose-response curve to the right
History of Alcohol in Nz
- Brought into NZ by europoean settlers
- began to be used in trade
- referred to as stinking/strong water (waipiro)
- by the 1850s was incorporated into Maori life although leaders were concerned about its harm on their communities. As such, dry areas were established and some Maori joined the prohibition movement
- It wasn’t until the 1890s when Maori began to match european settlers in alcohol related convictions (prior to this point they hadn’t been as heavy drinkers as Maori).
- The first Maori Doctors described drinking as a major social porblem
- Over time numerous alcohol regulations were passed in NZ with sexist and racist policy;
eg. 1847 Sale of Spirits to Natives Ordinance; prohibited the sale of spirits to Maori
eg. 1870 Outlying Districts Sale of Spirits Act; enabled the createion of a licensing system
eg. 1878 Native Licensing Act; allowed the establishment of dry districts
eg. 1895 Alcoholic Liquors Sale Control Amendment Act; Prevented Maori Women from Buying Alochol unless married to a european man
eg. 1904 Licensing Amendment Act Prevented Maori men from Buying Take-away alochol in most of the north island
After WW2 most of these regulations were repealed and with increased urbanisation, drinking became the norm for many maori through to present day
Inhalation
Gases
- are absorbed quickly through the capillaries of the lungs and move into the blood
- drugs in the form of vapours, gases or fine mists get into the blood very rapidly by the lungs
The blood goes directly from the lungs to the heart and one of the arteries goes directly to the brain, so inhaled drugs can pass into the brian wihtout being metabolised by the liver first (in first pass metabolism)
Intrathecal administration (parenteral)
Experimental Research with non-humans also may involve injecting a drug directly into the central nervous system (Brain/Spinal Cord) to increase experimental control
eg.
1. intrathecal - the needle is inserted between the base of the skull and the first vertebra. The drug gets left in the CSF
2. Intracerebroventricular - the needle is inserted directly in the brain’s ventricles to diffuse out into brain tissue
3. Intracerebral - needle is inserted directly into brain tissue - often using a canula.
For example, an antagonist could be injected into the hippocampus directly to put this area offline for a given study
Inhalation Administration
- inhalation
= Breathed into the lungs
Intramuscular parenteral administration
Intramuscular (i.m.) - a needle is inserted into the muscle
Kidneys role in metabolism
Functions;
- fluid balance
- detection and excretion of waste from the blood
- balance of vitamins, minerals and hormones
All occurs via filtration in the kidneys (generally after metabolism first in the liver)
Factors that influence/alter drug metabolism
- Stimulation of enzyme systems
- excess alcohol dehydrogenase has been found in the liver of heavy drinkers as the body prepares for the higher than average alcohol intake by increase the amount of enzyme required to break down the alcohol - Depression of enzyme systems
- disulfiram (antabuse) is a medication which blocks aldehyde dehydrogenase(used in alcohol metabolism). This means there is a built up of acetaldehyde as there isn’t the enzyme to break this down further to acetyl co-enzyme A. This buildup makes people feel very very sick - Age
- enzyme production and function (and therefore metabolism) changes with age
- liver function is less efficient in elderly people - Species
- levels of certain enzymes differ between species
Pharmacology
= the study of what a drug does to the body
Considers ingestion, digestion and excretion processes
Subcutaneous Parenteral Injection
Subcutaneous (s.c.)- a needle is inserted under the skin or in cutaneous tissue
Potency and Effectiveness
Primary Effect = intended result in a treatment
Side effect - unintended effect of a drug (anything other than the primary effect, may be harmful or not)
This is an arbitrary construct though, as it depends on why you’re taking the drug as to what is the primary and side effects
Class B
Deemed very high risk of harm and available on prescription
- Cannabis (hasish and Cannabis oil)
- Morphine
- Amphetamine
- MDMA
Orals administration
> When drugs are taken into the mouth and swallowed
- sometimes called ‘per oral’ (p.o.)
- the drug is then absorbed in the digestive system
Drugs may also be taken into the mouth but not swallowed
- technically still oral but absorbed through the buccal membranes
- eg. tobacco being held in the gums
Also can be taken as suppositories
- enter the digestive system through the other end (intrarectal)
- not as reliable as oral, but useful if oral is not possible
eg. for small kids if they can’t swallow the tablet
Smoking Rates in Maori and Pakeha and how this has changed with time
in 1962;
- Maori
Men; 58%
Women; 70%
- gen pop
Men; 38%
Women; 31%
In 1990;
over 50% of Maori were smokers
In 2009
Maori women aged 20 - 24 had the highest smoking rate in NZ (61%)
In 2011-2012
Rates of smoking in Maori declined to 41% compared to 18% in all NZ adults
Multiple programmes were intro’d to try and reduce smoking in the younger population (eg. age restrictions)
In 2021/2022
Maori 19.9%
rest of NZ adults 8%
Intravenous Parenteral administration
Intravenous (i.v.) - a needle is inserted into the vein
- is the fastest administration method
Hard Drugs in NZ
NZ has an unusual pattern of taking hard drugs. this is likely due to;
- geographic isolation
- strict border controls and good implementation of thiose controls
Resultingly, high profile drugs (cocaine and heroin) are much less common.
- Heroin use did see a peak in the 1970s as a result of the ‘Mr Asia’ syndicate an organisation that imported Heroin straight from asia
Optiate use is low (traditionally confided to ‘homebake) but prescription optiate use is on the rise
Cocaine use in NZ is extremely low
NZ is about 10 - 15 years behind global drug use trends. Hence only being hit by the opoid crisis
Synthetic drugs (amphetamines, ecstasy) are used more often. The rates of ecstasy and amphetamine (p) are high internaitonally, but are starting to be reduced due to crackdowns on clandestine labs and tighter border controls.
Hallucinogens
- we have low rates of LSD, Mushcroom and ketamine use
Party used
- used to be widely used by were banned in 2007
Active Transport
Transport method to move particles up against the concentration gradient using ATP/energy
Passive Transport
Is the most basic transport mechanism
- is diffusion ; whereby particles move from a high to low concentration
- doesn’t require energy expenditure
- is a slow transport mechanism
- This is mostly used by lipid soluble substances, but even non-lipid soluble substances can enter the intracellular space if there is a strong enough concentration gradient
The differing pattern of drinking between Maori and Non-Maori
Although on average, Maori and Europeans drink about the same amount in total, Maori tend to drink less frequently but consume twice as much per drinking session (aka binge drinking; which is by far the worst way to drink)
Maori are twice as likely to suffer severse alcohol related problems and four times as likely to die of a condition caused or made worse by alcohol (eg. Exacerabating existing health conditions
Superadditive responses/effects (potentiation)
Syngergistic effect of taking two drugs
shifts the curve left
Class A drugs
Are deemed to pose a very high risk of harm and are illegal
- LSD
- Heroin
- Cocaine
- Methamphetamine
- Psilocin and Psilocybin
Organs involved in Metabolism and Excretion
Most of this process is handled by the liver and kidneys