Monday, 27 July 2015

生蛇,唔好隨便買適患療膏用!Zovarix cream doesn't work for your shingles!!


在香港社區藥房工作,往往有令我‘大開眼界’的經驗,這都令我‘讚歎’香港的處方習慣,以下是我遇到的實例



1)年輕女士帶著處方紙來配藥,處方寫著適患療膏(Aciclovir 阿昔洛韋 cream) 陰道用,但處方只有這一個藥物

2)中年男士來我店質詢他醫生開的處方藥,其中一種藥,又是適患療膏(Aciclovir cream) 但醫生指示他要用來搽生蛇的患處

我真的很想衝去他們的醫生,勸他們不要浪費病人的錢和時間,要開藥,就開有效的,例如口服的抗疱疹藥 (oral aciclovir). 外敷的aciclovir 對生殖器疱疹和生蛇這類疱疹沒有療效,就連舒緩痛楚都不能!

要解釋為什麼,連循證都可以省了!口服的 Aciclovir 的生物利用度 (即口服後所剩下的劑量有多少會被身體吸收,從而產生療效)最多是20%,為何你可以預料到外敷的會比口服的更有效?




Working in the community in Hong Kong has surely 'broaden my horizons' of the local prescribing habit.... Here are some cases I have come across;

1) A young lady came in with a prescription for Zovarix, but on the script the application was for vaginal application (no oral antiviral)...

2) A older gentleman came in with loads of prescribed medicine for his shingles, one of them was Zovarix, and he was told to apply to the rash for his shingles


I really wanted to rush to their doctors and tell them, please don't waste the time and money of your patients, if you want to prescribe something, prescribe something that will work. Topical aciclovir (Zovarix) as an antiviral treatment for herpes zoster (shingles) DOES NOT WORK and for herpes simplex virus (HSV 2, in the cases of genital herpes as a sole agent for treatment) IS NOT EFFECTIVE! They don't even provide pain relief! 

You don't really need an evidence based explanation for it; aciclovir as an oral agent has poor bioavailability (max 20%), how do you expect the cream formulation to be more effective than the topical ones? 



Friday, 17 July 2015

每次殺不死你也醫好你?細菌都識唱!'What doesn't kill you makes you stronger' bacteria can sing this song too!

有多少次我見過朋友和家人的感冒藥裡面有抗生素?大約80%左右(在亞洲接近95%..)

當我看見這樣的抗生素處方,想也沒想我就會問他們,你們有肺部感染嗎?答案通常是沒有,但醫生告訴他們這是普通感冒,但他們會告訴醫生有非常糟糕的喉嚨痛(他們 ”糟糕" 的定義是之後還可以去一間貴價酒店擦一餐豐富的自助晚餐,顯然喉嚨不是怎麼痛吧),因此他們覺得抗生素可以幫助止痛,所以他們 “希望” 醫生會開藥。

親愛的朋友和家人(或其他自己去用抗生素來治療一些小病痛的人,抗生素的來源我就不想問了),請允許我解釋為什麼這是一個壞主意。



把不同種類的細菌想像成好多隊無家可歸的士兵。他們的工作是攻打成都(在這裡我們比喻為人類的身體)使它據為己有,成為的自己家園。顯然,成都的主人(人類)不會讓士兵們奪去自己的家園,所以他發明了超級武器(抗生素),試圖殺死所有侵略者。由於要殺死的士兵數以百萬計,成都主人在這麼短時間內根本無法將武器升級,來足以應付所有的士兵,然而每次戰鬥之後總會有一些殘兵可以幸存。幸運可以活著的士兵們會互相學習如何逃生和對抗成都的超級武器(抗生素耐藥性)。這就是故事的結局......不被殺的士兵們(細菌)經過每次戰鬥後就會越強,成都所使用的超級武器(抗生素)就再不管用了....

當我們開始使用抗生素來治療輕微感染像喉痛或普通感冒等小病,這就是噩夢的開始!咽喉痛通常是由病毒或細菌感染引起的。但它是一種自限性的病種(意思是說,病情多在3-4天或1週前會好轉,甚至消失)。如果你的喉嚨痛並沒有在1週內消失或者你喉嚨痛到甚至不能喝水,或者你有其他警號性的症狀,你就需要看醫生去排除嚴重感染或其他病的可能。

當你服用抗生素去治療喉嚨痛,那些“存活的細菌” 會因為長期暴露於低濃度抗生素的環境而產生抗藥性,因為:1)你可能沒有完成整個抗生素療程,使細菌有機會存活,2)抗生素無法達到的感染部位,細菌存活後抗藥的機會大大提高 3)錯誤的選擇抗生素治療。所有這些助抗藥性因素,超級細菌就會形成,這樣會使好多常規抗生素都變成一無事處。

後果?


我們可能會沒有有效的抗生素來治療嚴重以及危害生命的感染,本來容易治療的感染會變得難上加難以及有危害生命的危險!
想像一下,....在未來,因為病菌抗藥性,你的子孫可能需要去醫院打一些超強力的靜脈抗生素去治療一種原來在你的時代裡本來是很容易處理的感染,而且分分鐘會變成奪命感染啊!

相當可怕吧?




How many times have I come across antibiotics in the prescriptions of friends and families for the treatment of their common cold? Approximately 80% of the time (close to 95% in Asia ..) 

When I saw the antibiotics, without thinking I would ask if they were having a very bad chest infection? The replies were usually NO but doctor told them it was common cold and they had very bad sore throats (when they defined BAD, they would tell me they had just been to a fancy hotel to have a huge buffet dinner, apparently they could still swallow food properly), therefore they figured the antibiotics would help with the pain, so they would 'prefer' doctors to prescribe them. 

Dear friends and families (or other people out there who self medicate themselves with antibiotics for whatever minor ailments they have), please allow me to explain WHY it is a BAD idea. 

Imagine different kinds of bacteria as troops of homeless soldiers. Their job is to take over cities (metaphorically the physical being of humans) to make them their own homes. Obviously the owners of the cities (humans) won't just let them take their homes, they have invented super ammunition (antibiotics) to try to kill all the invaders. Since there are MILLIONS of homeless soldiers to kill, with the little time that the owners of cities have, they cannot upgrade ammunition fast enough to kill all the soldiers, and the high number of soldiers always result some runaways after each battle. The luckily alive soldiers would then learn from each other how to escape and improve themselves (antibiotic resistance) for the next battle. This is how the story goes... the homeless soldiers are getting stronger after each battle, and the ammunition owners use doesn't serve the purpose anymore....

This is the start of the nightmare when we use antibiotics for minor infections like sore throat or common colds! Sore throat is commonly caused by viral or bacterial infections. But it is a self-limiting conditions (which means it will go away in 3-4 days OR 1 week at most). It is important to get your sore throat seen to by a doctor when it does not go away in 1 week OR it is so sore that you cannot even drink water OR when you present with some other symptoms that suggest more serious conditions. 

When you take antibiotics for your sore throat, you are risking low grade persistent exposure of antibiotics to 'surviving bacteria', because 1) there are chances that you don't finish the course of antibiotics, 2) the antibiotics cannot reach to the site of infection 3) wrong choice of antibiotics.. All these factors can contribute to the development of super bacteria that would be resistant to all conventional antibiotics.

What could be the consequences?


We might run out of effective antibiotics to treat serious life threatening infection and eventually what was thought to be simple infection would be difficult to treat. 

Imagine again.... In future, your children or grandchildren might need to go to the hospital for intravenous antibiotics treatment for what was thought in your time to be an non complicated infection, and such infection had become life threatening! 

Pretty scary right? 


Media coverage of antibiotics resistance:

Abuse of antibiotics in China sparks fear of 'superbugs' +Hong Kong Free Press 2015
https://www.hongkongfp.com/2015/07/07/abuse-of-antibiotics-in-china-sparks-fear-of-superbugs/


Reference:

  1. WHO @2015 worldwide antibiotic resistance analysis http://www.who.int/drugresistance/documents/situationanalysis/en/
  2. Clinical knowledge summeries @NICE 2015 Sore throat  http://cks.nice.org.uk/sore-throat-acute#!background
  3. Centers of Disease Control and Prevention (US) @2015 http://www.cdc.gov/drugresistance/about.html


Wednesday, 15 July 2015

Lead dose spread out? Not really... 鉛劑量攤開?不是真的..


我們怎樣才會鉛中毒?


鉛中毒(鉛中毒)可以從不同的鉛來源;有機或無機的。

有機鉛是鉛含有“碳”和在汽油裡面發現的,它可以通過皮膚被吸收 (但非常少數會從這途徑中毒)。
無機鉛被定義為氧化鉛,金屬鉛和鉛的鹽,
它可以在焊接和水管中找到,大部分鉛中毒多數從這途徑發生,因為無機鉛水溶性
非常高,中毒劑量能低於0.5克。


接觸途徑?



可以經由呼吸道吸入無機鉛(〜40%),或者通過胃腸道吸收(〜10-15%),

但這途徑會令慢性中毒特別顯著如果患者生活或者工作環境受鉛污染


一旦鉛分發到血液,它會軟組織和骨骼吸收。鉛在血液通過腎臟排泄和​​清除較快,如果腎功能正常,

具有約30天的平均半衰期。然而,排鉛速度可因患者有慢性鉛暴露和大骨頭鉛存量而變得緩慢。

對比起成年人(3%-10%)兒童身體吸收已攝入的鉛(50-80%)高出5-8倍,因此兒童中毒的風險更大。
毒性也是由鐵和鈣缺乏增強。


接受血清血水平


(健康成人)
<10mcg /dl(0.48micromol/L)(美國標準BLL)
< 20mcg/dL (0.1 micromol/L) (英國標準)

(懷孕和嬰兒)
<5mcg/dL(美國標準BLL)


有什麼體徵和症狀....



急性中毒(> 80mcg / dL的血鉛水平)



●腹痛(“鉛絞痛”)

●便秘
●關節痛
●肌肉酸痛
●頭痛
●厭食
●性慾減退
●難以集中注意力和短期記憶障礙
●易怒
●疲勞過度
●睡眠障礙
●混亂,癲癇,腦病可見有極高濃度的鉛
●貧血
●腎病(範可尼型綜合徵)


慢性暴露(30至70mcg / dL)的



可以無病


 或者

肌痛
疲勞
易怒
失眠
厭食
受損的短期記憶
注意力不集中


更嚴重的健康問題.....



高血壓                      (骨鉛,累積鉛暴露的反映,估計是發展中國家高血壓的標準老齡化研究的一個獨立危險因素)

死亡率和心血管效應(長期接觸具有低鉛含量為20〜29mcg /dL(0.97至1.40 micromol/L),
                                   和甚至小於10mcg/dL(0.48micromol/L)在一個報告中,增加死亡率已指出和血含鉛有關
神經精神效應            (腦病變多數發生在兒童身上, 血含鉛高的兒童可無症狀,但有機會有智力障礙和行為障礙。


生殖效應  (A)              (男子40和70微克/分升(1.93之間慢性鉛暴露[和血鉛水平3.38micromol / L)已經在一些研究中發現有精子形態異常的百分之增加,
                                  降低精子的濃度,總精子數量和總活動精子數)

生殖效應  (B)                (鉛容易穿過胎盤。發現孕婦出現流產,死胎數量增加,和早產都有相當高的鉛暴露。
                                     根據醫學報導,血,靜脈血液,臍帶血和骨含鉛較高母親所生的嬰兒多有降低出生體重和認知障礙)


How can we get lead poisoning? 


Lead poisoning (plumbism) can be from different source of lead; organic or inorganic.
Organic lead is lead that contained 'carbon' and is usually found in gasoline and it can be absorbed through the skin (which rarely causes any poisoning or toxicity). Inorganic lead is defined as lead oxides, metallic lead and lead salts, which can be found in soldering and  water pipes. Poisoning or toxicities are usually caused by ingestion inorganic lead as it is highly water soluble, toxic dose can be as low as 0.5grams. 

Route of exposure?

Inorganic lead via inhalation (~40%), and via gastrointestinal absorption (~10-15%) BUT it can be a significant contributor, particularly when working and/or eating in a lead-contaminated environment. 

Once absorbed, lead is then distributed to the blood, soft tissues, and skeleton. Lead in blood is excreted via the kidneys and cleared comparatively fast, with a mean half-life of about 30 days if renal function is normal. However, blood clearance can be slower in people with a long history of lead exposure and large bone stores. Children absorb considerably more ingested lead (quoted ranges 50-80%) than adults (3-10%) and are thus at greater risk of developing toxicity. Toxicity is also enhanced by iron and calcium deficiency.


Acceptable serum blood level

(Healthy Adults) <10mcg/dL (0.48 micromol/L) (US BLL standard, readjusted to lower threshold in view of adverse effect in low exposure)
< 20mcg/dL (0.1 micromol/L) (UK standard)

(Pregnancy and infants)
mcg/dL (US BLL standard)

What are signs and symptoms of....

Acute poisoning (> 80mcg/dL serum lead level)


Abdominal pain ("lead colic")

Constipation

Joint pains

Muscle aches

Headache

Anorexia

Decreased libido

Difficulty concentrating and deficits in short-term memory

Irritability

Excessive fatigue

Sleep disturbance

Confusion, seizures, and encephalopathy can be seen with extremely high levels of lead

Anemia

Nephropathy (Fanconi-type syndrome)

Chronic exposure (30 to 70mcg/dL)


  • can be asymptomatic 
               OR
  • myalgias
  • fatigue
  • irritability
  • insomnia
  • anorexia
  • impaired short-term memory
  • difficulty concentrating
More serious health issues ..... 


  • Hypertension (Bone lead, a reflection of cumulative lead exposure, was estimated to be an independent risk factor of developing hypertension in Normative Aging Study)
  • Mortality and cardiovascular effects (Chronic exposure with low lead levels 20 to 29mcg/dL (0.97 to 1.40 micromol/L), and even less than 10 mcg/dL (0.48 micromol/L) in one report, has been linked to an increase in mortality)
  • Neuropsychiatric effects  Encephalopathy may occur and is more common in children. Children with elevated lead concentrations may be asymptomatic apart from intellectual deficits and behavioural disorders.
  • Reproductive effects (A)  (Men with chronic lead exposure [and blood lead levels between 40 and 70 mcg/dL (1.93 to 3.38micromol/L) have been found in some studies to have an increased percent of sperm with abnormal morphology and decreased sperm concentration, total sperm count, and total motile sperm count)
  •  Reproductive effects (B) Lead readily crosses the placenta. Increased number of miscarriages, stillbirths, and preterm delivery appear to be related to high lead exposures in pregnant women. Reduced birth weight and cognitive impairments also have been reported in babies born to mothers with elevated lead in venous blood, cord blood, or bone.

References: 
Summarised by KS Lai @2015