Pseudoephedrine

Pseudoephedrine
Systematic (IUPAC) name
(S,S)-2-methylamino-1-phenylpropan-1-ol
Clinical data
Trade names Afrinol, Sudafed, Sinutab(UK)
AHFS/Drugs.com monograph
MedlinePlus a682619
  • AU: B2
  • US: C (Risk not ruled out)
  • AU: Pharmacist Only (S3)
  • CA: S3
  • UK: Pharmacy medicines
  • US: Behind the Counter (BTC) Rx only in Oregon and Mississippi
Low
oral, insufflation
Pharmacokinetic data
Bioavailability ~100%[1]
Metabolism hepatic (10–30%)
Half-life 4.3–8 hours[1]
Excretion 43–96% renal[1]
Identifiers
90-82-4 Yes
R01BA02
PubChem CID 7028
DrugBank DB00852 Yes
ChemSpider 6761 Yes
UNII 7CUC9DDI9F Yes
KEGG D08449 Yes
ChEBI CHEBI:51209 Yes
ChEMBL CHEMBL1590 Yes
Chemical data
Formula C10H15NO
165.23
 Yes (what is this?)  (verify)

Pseudoephedrine (/ˌsjuːdoʊ.ɨˈfɛdrɪn/ or /ˌsjuːdoʊˈɛfɨdriːn/; PSE) is a sympathomimetic drug of the phenethylamine and amphetamine chemical classes. It may be used as a nasal/sinus decongestant, as a stimulant, or as a wakefulness-promoting agent.[2]

The salts pseudoephedrine hydrochloride and pseudoephedrine sulfate are found in many over-the-counter preparations, either as a single ingredient or (more commonly) in combination with antihistamines, guaifenesin, dextromethorphan, and/or paracetamol (acetaminophen) or an NSAID (such as aspirin or ibuprofen).

Chemistry

Pseudoephedrine is a diastereomer of ephedrine and is readily reduced into methamphetamine or oxidized into methcathinone.

Two pairs of enantiomers: ephedrine (top) and pseudoephedrine (bottom)

Nomenclature

The dextrorotary (+)- or d- enantiomer is (1S,2S)-pseudoephedrine, whereas the levorotating (−)- or l- form is (1R,2R)-pseudoephedrine.

In the outdated d/l system (+)-pseudoephedrine is also referred to as l-pseudoephedrine and (−)-pseudoephedrine as d-pseudoephedrine (in the Fisher projection then the phenyl ring is drawn at bottom).[3][4]

Often the d/l system (with small caps) and the d/l system (with lower-case) are confused. The result is that the dextrorotary d-pseudoephedrine is wrongly named d-pseudoephedrine and the levorotary l-ephedrine (the diastereomer) wrongly l-ephedrine.

The IUPAC names of the two enantiomers are (1S,2S)- respectively (1R,2R)-2-methylamino-1-phenylpropan-1-ol. Synonyms for both are psi-ephedrine and threo-ephedrine.

Pseudoephedrine is the International Nonproprietary Name of the (+)-form, when used as pharmaceutical substance.[5]

Synthesis

Although pseudoephedrine occurs naturally as an alkaloid in certain plant species (for example, as a constituent of extracts from the Ephedra species, also known as ma huang, in which it occurs together with other isomers of ephedrine), the majority of pseudoephedrine produced for commercial use is derived from yeast fermentation of dextrose in the presence of benzaldehyde. In this process, specialized strains of yeast (typically a variety of Candida utilis or Saccharomyces cerevisiae) are added to large vats containing water, dextrose and the enzyme pyruvate decarboxylase (such as found in beets and other plants). After the yeast has begun fermenting the dextrose, the benzaldehyde is added to the vats, and in this environment the yeast converts the ingredients to the precursor l-phenylacetylcarbinol (L-PAC). L-PAC is then chemically converted to pseudoephedrine via reductive amination.[6]

The bulk of pseudoephedrine is produced by commercial pharmaceutical manufacturers in India and China, where economic and industrial conditions favor its mass production for export.[7]

Mechanism of action

Pseudoephedrine is a sympathomimetic amine. Its principal mechanism of action relies on its direct action on the adrenergic receptor system.[8][9] The vasoconstriction that pseudoephedrine produces is believed to be principally an α-adrenergic receptor response.[10]

Pseudoephedrine acts on α- and β2-adrenergic receptors, to cause vasoconstriction and relaxation of smooth muscle in the bronchi, respectively.[8][9] α-adrenergic receptors are located on the muscles lining the walls of blood vessels. When these receptors are activated, the muscles contract, causing the blood vessels to constrict (vasoconstriction). The constricted blood vessels now allow less fluid to leave the blood vessels and enter the nose, throat and sinus linings, which results in decreased inflammation of nasal membranes, as well as decreased mucus production. Thus, by constriction of blood vessels, mainly those located in the nasal passages, pseudoephedrine causes a decrease in the symptoms of nasal congestion. Activation of β2-adrenergic receptors produces relaxation of smooth muscle of the bronchi,[8] causing bronchial dilation and in turn decreasing congestion (although not fluid) and difficulty breathing.

Medical uses

Pseudoephedrine is a stimulant, but it is well known for shrinking swollen nasal mucous membranes, so it is often used as a decongestant. It reduces tissue hyperemia, edema, and nasal congestion commonly associated with colds or allergies. Other beneficial effects may include increasing the drainage of sinus secretions, and opening of obstructed Eustachian tubes. The same vasoconstriction action can also result in hypertension, which is a noted side effect of pseudoephedrine.

Pseudoephedrine can be used either as oral or as topical decongestant. The advantage of oral pseudoephedrine over topical nasal preparations is that it does not cause rebound congestion (rhinitis medicamentosa). However, due to its stimulating qualities, it is more likely to cause adverse effects, including hypertension, sweating, insomnia, and anxiety.

According to one study, pseudoephedrine may show effectiveness as an antitussive drug (suppression of cough).[11]

Pseudoephedrine is also used by some ADHD patients to self-medicate, due to its stimulant properties.[12]

Indications

Pseudoephedrine is indicated for the treatment of:

Pseudoephedrine is also indicated for vasomotor rhinitis, and as an adjunct to other agents in the optimum treatment of allergic rhinitis, croup, sinusitis, otitis media, and tracheobronchitis.[13]

Pseudoephedrine is also used as a first-line prophylactic for recurrent priapism. Erection is largely a parasympathetic response, so the sympathetic action of pseudoephedrine may serve to relieve this condition.

Treatment for urinary incontinence is an off-label use ("unlabeled use") for these medications.[14]

Adverse effects

Common adverse drug reactions (ADRs) associated with pseudoephedrine therapy include: CNS stimulation, insomnia, nervousness, excitability, dizziness and anxiety. Infrequent ADRs include: tachycardia or palpitations. Rarely, pseudoephedrine therapy may be associated with mydriasis (dilated pupils), hallucinations, arrhythmias, hypertension, seizures and ischemic colitis;[15] as well as severe skin reactions known as recurrent pseudo-scarlatina, systemic contact dermatitis, and nonpigmenting fixed drug eruption.[16] Pseudoephedrine, particularly when combined with other drugs including narcotics, may also play a role in the precipitation of episodes of paranoid psychosis.[17] It has also been reported that pseudoephedrine, among other sympathomimetic agents, may be associated with the occurrence of stroke.[18]

Precautions and contraindications

It is recommended that pseudoephedrine not be used in patients with: diabetes mellitus, cardiovascular disease, severe or uncontrolled hypertension, severe coronary artery disease, prostatic hypertrophy, hyperthyroidism, closed angle glaucoma, or by pregnant women.[15]

Patients who are prone to anxiety or panic attacks should use pseudoephedrine with caution, as anxiety and restlessness are common side effects, mostly due to the drug's stimulant properties.

Since nasal congestion is considered to be a relatively minor ailment, alternatives are preferred in patients with these conditions. Appropriate alternatives may include saline sprays/instillations, depending on the patient's condition. Topical decongestants should be used with caution and for no longer than three days to avoid rhinitis medicamentosa.

Interactions

Concomitant or recent (previous fourteen days) monoamine oxidase inhibitor use can lead to hypertensive reactions, including hypertensive crises.[15]

The antihypertensive effects of methyldopa, mecamylamine, reserpine and veratrum alkaloids may be reduced by sympathomimetics. Beta-adrenergic antagonists may also interact with sympathomimetics. Increase of ectopic pacemaker activity can occur when pseudoephedrine is used concomitantly with digitalis. Antacids increase the rate of pseudoephedrine absorption, while kaolin decreases it.

Common brand names

The following is a list of consumer medicines that either currently contain pseudoephedrine, or have since switched to alternative, such as phenylephrine.

Other uses

There have been reports of off-label uses of pseudoephedrine for its stimulant properties. Long-distance truck drivers and athletes, for example, have reportedly used pseudoephedrine as a stimulant to increase their state of alertness/awareness.

Manufacture of methamphetamine and methcathinone

Its membership in the amphetamine class has made pseudoephedrine a sought-after chemical precursor in the illicit manufacture of methamphetamine and methcathinone. As a result of the increasing regulatory restrictions on the sale and distribution of pseudoephedrine, many pharmaceutical firms have reformulated, or are in the process of reformulating medications to use alternative, but less effective,[19] decongestants, such as phenylephrine.

Many retailers, such as Target, Walgreens, CVS, Rite Aid, and Winn-Dixie in the US, have created corporate policies restricting the sale of pseudoephedrine-containing products. Their policies restrict sales by limiting purchase quantities and requiring a minimum age with proper identification. These requirements are similar to and sometimes more stringent than existing law. Internationally, pseudoephedrine is listed as a Table I precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances.[20]

Sports

Pseudoephedrine was on the banned substances IOC list until 2004, when the World Anti Doping Agency WADA list replaced the IOC list. Although WADA initially only monitored pseudoephedrine, it is once again on the banned list starting January 1, 2010.[21]

Pseudoephedrine is excreted through urine, and concentration in urine of this drug shows a large inter-individual spread; that is, the same dose can give a vast difference in urine concentration for different individuals [22] Pseudoephedrine is approved to be taken up to 240 mg per day. In seven healthy male subjects this dose yielded a urine concentration range of 62.8 to 294.4 microgram per milliliter (µg/ml) with mean ± standard deviation 149 ± 72 µg/ml [23] Thus, normal dosage of 240 mg pseudoephedrine per day can result in urine concentration levels exceeding the limit of 150 µg/ml set by WADA for about half of every user.[24]

In 1995 Canadian rower Silken Laumann was stripped of her medals after testing positive for pseudoephedrine.[25]

Romanian gymnast Andreea Răducan was stripped of her gold medal at the 2000 Sydney Olympics after testing positive. She took two pills given to her by the team coach for a cold. Although she was stripped of the overall gold medal, she kept her other medals, and, unlike in most other doping cases, was not banned from competing again; only the team doctor was banned for a number of years. Ion Ţiriac, the president of the Romanian Olympic Committee, resigned over the scandal.[26][27]

In the 2010 Vancouver Olympics the IOC issued a reprimand against the Slovakian ice hockey player Lubomir Visnovsky for usage of pseudoephedrine.[28]

In the 2014 Sochi Olympics the team Sweden and Washington Capitals ice hockey player Nicklas Bäckström was banned for usage of pseudoephedrine. Bäckström was claiming using it as allergy medication.[29]

Detection of use

Pseudoephedrine may be quantitated in blood, plasma or urine to monitor any possible performance-enhancing use by athletes, confirm a diagnosis of poisoning or assist in a medicolegal death investigation. Many commercial immunoassay screening tests directed at the amphetamines cross-react appreciably with pseudoephedrine, but chromatographic techniques can easily distinguish pseudoephedrine from other phenethylamine derivatives. Blood or plasma pseudoephedrine concentrations are typically in the 50–300 µg/l range in persons taking the drug therapeutically, 500–3000 µg/l in abusers or poisoned patients and 10–70 mg/l in cases of acute fatal overdosage.[30][31]

National legislation

Australia

A warning at an Australian pharmacy

Illicit diversion of pseudoephedrine in Australia has caused significant changes to the way the products are regulated. As of 2006, all products containing pseudoephedrine have been rescheduled as either "Pharmacist Only Medicines" (Schedule 3) or "Prescription Only Medicines" (Schedule 4), depending on the amount of pseudoephedrine in the product. A Pharmacist Only Medicine may only be sold to the public if a pharmacist is directly involved in the transaction. These medicines must be kept behind the counter, away from public access.

Pharmacists are also encouraged (and in some states required) to log purchases with the online database Project STOP.[32] This system aims to prevent individuals from purchasing small quantities of pseudoephedrine from many different pharmacies.

As a result, many pharmacies no longer stock Sudafed, the common brand of pseudoephedrine cold/sinus tablets, opting instead to sell Sudafed PE, a phenylephrine product which has not been proven effective in clinical trials.[33][34][35]

Colombia

The Colombian government prohibited the trade of pseudoephedrine in 2010.[36]

Mexico

On November 23, 2007, the use and trade of pseudoephedrine in Mexico was made illicit, as it was argued that it was extremely popular as a precursor in the synthesis of methamphetamine.[37]

New Zealand

In New Zealand, from 15 October 2004, as a result of large intercepts of pseudoephedrine and ephedrine, any product containing these substances, e.g. cold and flu medicines, were classified as Class C Part III (partially exempted) controlled drugs in the Misuse of Drugs Act 1975.[38] New Zealand Customs and police officers are continuing to make large interceptions of precursor substances believed to be destined for methamphetamine production. On 9 October 2009, Prime Minister John Key announced pseudoephedrine-based cold and flu tablets would become prescription-only drugs and reclassified as a class B2 drug.[39] The Misuse of Drugs Amendment Bill 2010 has not yet been finalised.[40]

United Kingdom

In the UK, pseudoephedrine is available over the counter under the supervision of a qualified pharmacist, or on prescription. In 2007, the MHRA reacted to concerns over diversion of ephedrine and pseudoephedrine for the illicit manufacture of methamphetamine by introducing voluntary restrictions limiting over the counter sales to one box containing no more than 720 mg of pseudoephedrine in total per transaction. These restrictions became law in April 2008.[41] However no form of ID is required.

United States

The United States Congress has recognized that pseudoephedrine is used in the illegal manufacture of methamphetamine. In 2005, the Committee on Education and the Workforce heard testimony concerning education programs and state legislation designed to curb this illegal practice.

Attempts to control the sale of the drug date back to 1986, when federal officials at the Drug Enforcement Administration (DEA) first drafted legislation, later proposed by Senator Bob Dole, R-KS, that would have placed a number of chemicals used in the manufacture of illicit drugs under the Controlled Substances Act. The bill would have required each transaction involving pseudoephedrine to be reported to the government, and federal approval of all imports and exports. Fearing this would limit legitimate use of the drug, lobbyists from over the counter drug manufacturing associations sought to stop this legislation from moving forward, and were successful in exempting from the regulations all chemicals that had been turned into a legal final product, such as Sudafed.[42]

Prior to the passage of the Combat Methamphetamine Epidemic Act of 2005, sales of the drug became increasingly regulated, as DEA regulators and pharmaceutical companies continued to fight for their respective positions. The DEA continued to make greater progress in their attempts to control pseudoephedrine as methamphetamine production skyrocketed, becoming a serious problem in the Western United States. When purity dropped, so did the number of people in rehab, and people admitted to emergency rooms with methamphetamine in their systems. However, this reduction in purity was usually short lived as methamphetamine producers eventually found a way around the new regulations.[43]

Congress passed the Combat Methamphetamine Epidemic Act of 2005 ("CMEA") as an amendment to the renewal of the USA PATRIOT Act. Signed into law by president George W. Bush on March 6, 2006, the act amended 21 U.S.C. § 830, concerning the sale of pseudoephedrine-containing products. The law mandated two phases, the first needing to be implemented by April 8, 2006, and the second phase to be completed by September 30, 2006. The first phase dealt primarily with implementing the new buying restrictions based on amount, while the second phase encompassed the requirements of storage, employee training, and record keeping.[44] Though the law was mainly directed at pseudoephedrine products it also applies to all over the counter products containing:ephedrine, pseudoephedrine, and phenylpropanolamine, their salts, optical isomers, and salts of optical isomers.[44] Pseudoephedrine was defined as a "scheduled listed chemical product" under 21 U.S.C. § 802(45(A)). The act included the following requirements for merchants ("regulated sellers") who sell such products:

In regards to the identification that may be used by an individual buying pseudoephedrine products the following constitute acceptable forms of identification:

Most states also have laws regulating pseudoephedrine.

Alabama, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Hawaii (as of May 1, 2009) Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana (as of August 15, 2009), Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska,[45] Nevada, New Jersey, North Carolina, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia and Wisconsin have laws requiring pharmacies to sell pseudoephedrine "behind the counter" and to collect personal information from purchasers.[46]

Oregon and Mississippi require a prescription for the purchase of products containing pseudoephedrine.[47][48] Oregon reduced the number of methamphetamine lab seizures from 467 in 2004, (the final full year before implementation of the prescription only law),[49] to a new low of 12 in 2009.[50] Some municipalities in Missouri have enacted similar ordinances, including Washington,[51] Union,[52] New Haven,[53] Cape Girardeau[54] and Ozark.[55] Certain pharmacies in Terre Haute, Indiana do so as well.[56]

Another approach to controlling the drug on the state level which has been mandated by some state governments to control the purchases of their citizens is the use of electronic tracking systems, which require the electronic submission of specified purchaser information by all retailers who sell pseudoephedrine. Several states that have implemented tracking systems are: Tennessee, Kentucky, and Oklahoma.[57] These states have had mixed results in reducing the number of methamphetamine laboratory seizures in their states. Prior to implementation of the system in Tennessee in 2005, methamphetamine laboratory seizures totaled 1,497 in 2004, but were reduced to 955 in 2005, and 589 in 2009.[50] Kentucky's program was implemented statewide in 2008, but since statewide implementation, the number of laboratory seizures has actually increased.[50] Oklahoma initially experienced success with their tracking system after implementation in 2006, as the number of seizures dropped in that year and again in 2007. However in 2008, seizures began rising again, and have continued to rise in 2009.[50]

Turkey

In Turkey, medications containing pseudoephedrine are available with prescription only.[58]

See also

References

  1. ↑ 1.0 1.1 1.2 Laurence L Brunton, ed. (2006). Goodman & Gilman's The Pharmacological Basis of Therapeutics (11th ed.). New York: McGraw-Hill Medical Publishing Division. ISBN 0-07-142280-3.
  2. ↑ Hodges, K; Hancock, S; Currell, K; Hamilton, B; Jeukendrup, AE (February 2006). "Pseudoephedrine enhances performance in 1500-m runners". US National Library of Medicine National Institutes of Health 38 (2): 329–33. doi:10.1249/01.mss.0000183201.79330.9c. PMID 16531903.
  3. ↑ Popat N. Patil, A. Tye and J.B. LaPidus (1965). "A pharmacological study of the ephedrine isomers". JPET 148 (2): 158–168. PMID 14301006.
  4. ↑ Martindale (1989). Edited by Reynolds JEF, ed. Martindale: The complete drug reference (29th ed.). London: Pharmaceutical Press. ISBN 0-85369-210-6.
  5. ↑ Proposed International Non-Proprietary Names (Prop. I.N.N.): List 11 WHO Chronicle, Vol. 15, No. 8, August 1961, pp. 314–20
  6. ↑ Oliver AL, Anderson BN, Roddick FA; Anderson; Roddick (1999). "Factors affecting the production of L-phenylacetylcarbinol by yeast: a case study". Adv. Microb. Physiol. Advances in Microbial Physiology 41: 1–45. doi:10.1016/S0065-2911(08)60164-2. ISBN 978-0-12-027741-4. PMID 10500843.
  7. ↑ Suo, Steve. Clamp down on shipments of raw ingredients. The Oregonian; 6 October 2004. From a version reprinted on a U.S. congressional caucus website.
  8. ↑ 8.0 8.1 8.2 American Medical Association, AMA Department of Drugs (1977). AMA Drug Evaluations. PSG Publishing Co., Inc. p. 627.
  9. ↑ 9.0 9.1 Thomson/Micromedex (2007). Drug Information for the Health Care Professional,Volume 1,. Greenwood Village, CO. p. 2452.
  10. ↑ Drew, CD; Knight, GT; Hughes, DT; Bush, M (1978). "Comparison of the effects of D-(−)-ephedrine and L-(+)-pseudoephedrine on the cardiovascular and respiratory systems in man". British Journal of Clinical Pharmacology 6 (3): 221–225. doi:10.1111/j.1365-2125.1978.tb04588.x. PMC 1429447. PMID 687500.
  11. ↑ Kiyoshi Minamizawa et al. (2006). "Effect of d-Pseudoephedrine on Cough Reflex and Its Mode of Action in Guinea Pigs". Journal of Pharmacological Sciences 102 (1): 136–142. doi:10.1254/jphs.FP0060526. PMID 16974066.
  12. ↑ http://www.healthcentral.com/adhd/h/pseudoephedrine-to-treat-attention-deficit-hyperactivity-disorder.html
  13. ↑ 13.0 13.1 Bicopoulos D, editor. AusDI: Drug information for the healthcare professional, 2nd edition. Castle Hill: Pharmaceutical Care Information Services; 2002.
  14. ↑ "Selecting Medications for the Treatment of Urinary Incontinence – January 15, 2005 – American Family Physician". Aafp.org. Retrieved 2012-05-06.
  15. ↑ 15.0 15.1 15.2 Rossi S, editor. Australian Medicines Handbook 2006. Adelaide: Australian Medicines Handbook; 2006. ISBN 0-9757919-2-3
  16. ↑ Vidal C, Prieto A, Pérez-Carral C, Armisén M; Prieto; Pérez-Carral; Armisén (April 1998). "Nonpigmenting fixed drug eruption due to pseudoephedrine". Ann. Allergy Asthma Immunol. 80 (4): 309–10. doi:10.1016/S1081-1206(10)62974-2. PMID 9564979.
  17. ↑ "Adco-Tussend". Home.intekom.com. 1993-03-15. Retrieved 2012-05-06.
  18. ↑ Cantu C, Arauz A, Murillo-Bonilla LM, López M, Barinagarrementeria F; Arauz; Murillo-Bonilla; López; Barinagarrementeria (July 2003). "Stroke associated with sympathomimetics contained in over-the-counter cough and cold drugs". Stroke 34 (7): 1667–72. doi:10.1161/01.STR.0000075293.45936.FA. PMID 12791938.
  19. ↑ Hatton RC, Winterstein AG, McKelvey RP, Shuster J, Hendeles L; Winterstein; McKelvey; Shuster; Hendeles (March 2007). "Efficacy and safety of oral phenylephrine: systematic review and meta-analysis". Ann Pharmacother 41 (3): 381–90. doi:10.1345/aph.1H679. PMID 17264159.
  20. ↑ "Microsoft Word - RedListE2007.doc" (PDF). Retrieved 2012-05-06.
  21. ↑ "WADA 2010 Prohibited List Now Published – World Anti-Doping Agency". Wada-ama.org. Retrieved 2012-05-06.
  22. ↑ "Elimination of ephedrines in urine following multiple dosing the consequences for athletes in relation to doping control". Retrieved 2014-02-24.
  23. ↑ Strano-Rossi, S.; Leone, D.; Torre, X. D. L.; Botrè, F. (2009). "The Relevance of the Urinary Concentration of Ephedrines in Anti-Doping Analysis: Determination of Pseudoephedrine, Cathine, and Ephedrine After Administration of Over-the-Counter Medicaments". Therapeutic Drug Monitoring 31 (4): 520. doi:10.1097/FTD.0b013e3181ac6006.
  24. ↑ http://www.wada-ama.org/Documents/World_Anti-Doping_Program/WADP-Prohibited-list/WADA_Additional_Info_Pseudoephedrine_2010_EN.pdf
  25. ↑ "Silken tests positive". Retrieved 2014-02-24.
  26. ↑ "Summer Olympics 2000 Raducan tests positive for stimulant". Assets.espn.go.com. 2000-09-26. Retrieved 2012-05-06.
  27. ↑ "Amanar Tops Romanian Money List". International Gymnast Magazine Online. 15 October 2000. Archived from the original on 2001-07-15. Retrieved 2012-05-06.
  28. ↑ "IOC issues a reprimand against Slovakian ice hockey player". Retrieved 2014-02-24.
  29. ↑ "Sweden's Bäckström tests positive for banned substance". Retrieved 2014-02-24.
  30. ↑ Boland DM, Rein J, Lew EO, Hearn WL. Fatal cold medication intoxication in an infant; Rein; Lew; Hearn (2003). "Fatal cold medication intoxication in an infant". J. Anal. Toxicol. 27 (7): 523–526. doi:10.1093/jat/27.7.523. PMID 14607011.
  31. ↑ R. Baselt (2008). Disposition of Toxic Drugs and Chemicals in Man (8th ed.). Foster City, CA: Biomedical Publications. pp. 1344–1346.
  32. ↑ "Project STOP video – Online Advertising". Innovationrx.com.au. Retrieved 2012-05-06.
  33. ↑ Horak, F; Zieglmayer, P; Zieglmayer, R; Lemell, P; Yao, R; Staudinger, H; Danzig, M (2009). "A placebo-controlled study of the nasal decongestant effect of phenylephrine and pseudoephedrine in the Vienna Challenge Chamber". Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology 102 (2): 116–20. doi:10.1016/S1081-1206(10)60240-2. PMID 19230461.
  34. ↑ Hatton, RC; Winterstein, AG; McKelvey, RP; Shuster, J; Hendeles, L (2007). "Efficacy and safety of oral phenylephrine: Systematic review and meta-analysis". The Annals of pharmacotherapy 41 (3): 381–90. doi:10.1345/aph.1H679. PMID 17264159.
  35. ↑ Eccles, R (2007). "Substitution of phenylephrine for pseudoephedrine as a nasal decongeststant. An illogical way to control methamphetamine abuse". British Journal of Clinical Pharmacology 63 (1): 10–4. doi:10.1111/j.1365-2125.2006.02833.x. PMC 2000711. PMID 17116124.
  36. ↑ "Gobierno prohĂbe antigripales con pseudoefedrina a partir de finales de 2010 – Archivo – Archivo Digital de Noticias de Colombia y el Mundo desde 1.990" [Government Prohibits Flu Pseudoephedrine in Late 2010 - Archive - News Archive Digital Colombia and the World since 1990] (in Spanish). Eltiempo.com. 8 July 2009 [Published 11 August 2009]. Retrieved 2012-05-06.
  37. ↑ "Prohibirán definitivamente uso de pseudoefedrina" [A Permanent Ban on Pseudoephedrine] (in Spanish). 23 November 2007 [Published 2 December 2007]. Retrieved 17 December 2013.
  38. ↑ "Ephedrine and Pseudoephedrine to Become Controlled Drugs". Medsafe, New Zealand Medicines and Medical Devices Safety Authority. Archived from the original on 2007-03-08.
  39. ↑ "Chemical Brothers". Listener (New Zealand). Archived from the original on 2010-05-23.
  40. ↑ "Digest No. 1776". Parliament.nz. Retrieved 2012-05-06.
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  42. ↑ "Search OregonLive.com". The Oregonian.
  43. ↑ "How Legislation Changed Meth Purity" (PDF). The Oregonian.
  44. ↑ 44.0 44.1 44.2 "DEA Interim Final Regulation: Ephedrine, Pseudoephedrine, and Phenylpropanolamine Requirements" (PDF). Archived from the original (PDF) on 2006-10-18.
  45. ↑ "Nebraskans to sign for Sudafed". Lincoln Journal-Star. 13 Mar 2006. Retrieved 20 Aug 2012.
  46. ↑ "PSE". nacds.org. Retrieved 2014-10-15.
  47. ↑ "MS Senate passes bill to restrict pseudoephedrine sales". Associated Content (WLOX). February 2, 2010. Retrieved May 8, 2010.
  48. ↑ Bovett, Rob (November 15, 2010). "How to Kill the Meth Monster". The New York Times. Retrieved November 16, 2010.
  49. ↑ http://www.leg.state.or.us/cgi-bin/searchMeas.pl
  50. ↑ 50.0 50.1 50.2 50.3 "DEA, Maps of Methamphetamine Lab Incidents". Justice.gov. Retrieved 2012-05-06.
  51. ↑ "Council Passes Law Restricting Pseudoephedrine". The Washington Missourian. July 7, 2009. Retrieved December 10, 2010.
  52. ↑ "Union Board Approves Pseudoephedrine Ordinance". The Washington Missourian. October 13, 2009. Retrieved December 10, 2010.
  53. ↑ "New Haven Passes Prescription Law". The Washington Missourian. November 11, 2010. Retrieved December 10, 2010.
  54. ↑ "Cape Girardeau City Council passes prescription requirement for pseudoephedrine". The Southeast Missourian. December 7, 2010. Retrieved December 10, 2010.
  55. ↑ "Ozark passes pseudoephedrine ban: Drug now prescription-only". CCHeadliner.com. June 18, 2013. Retrieved December 17, 2013. (subscription required (help)).
  56. ↑ Trigg, Lisa (May 20, 2010). "Four Valley pharmacies to require prescriptions for certain products to help fight meth problem". Terre Haute Tribune-Star. (Subscription required, free access for first 30 days)
  57. ↑ "2009 Congressional Report Final" (PDF). namsdl.org. Retrieved 2013-01-02.
  58. ↑ "Kontrole Tabi İlaçlar" (PDF). Social Security Institution of Republic of Turkey. July 2013.